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list | update_date
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sequence |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
0708.1249 | Kunihito Ioka | Kunihito Ioka, Kohta Murase, Kenji Toma, Shigehiro Nagataki, Takashi
Nakamura | Unstable GRB photospheres and electron-positron annihilation lines | 4 pages, 2 figures | Astrophys.J.670:L77-L80,2007 | 10.1086/524405 | KEK-TH-1226, KEK-Cosmo-6 | astro-ph | null | We propose an emission mechanism of prompt gamma-ray bursts (GRBs) that can
reproduce the observed non-thermal spectra with high radiative efficiencies,
>50%. Internal dissipation below a photosphere can create a radiation-dominated
thermal fireball. If electron-positron pairs outnumber protons, radiative
acceleration of pairs drives the two-stream instabilities between pairs and
protons, leading to the ``proton sedimentation'' in the accelerating pair
frame. Pairs are continuously shock heated by proton clumps, scattering the
thermal photons into the broken power-law shape, with the non-thermal energy
that is comparable to the proton kinetic energy, consistent with observations.
Pair photospheres become unstable around the radius of the progenitor star
where strong thermalization occurs, if parameters satisfy the observed spectral
(Yonetoku) relation. Pair annihilation lines are predicted above continua,
which could be verified by GLAST.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 11:26:59 GMT"
}
] | 2015-04-23T00:00:00 | [
[
"Ioka",
"Kunihito",
""
],
[
"Murase",
"Kohta",
""
],
[
"Toma",
"Kenji",
""
],
[
"Nagataki",
"Shigehiro",
""
],
[
"Nakamura",
"Takashi",
""
]
] |
0708.1250 | Jean-Marc Laget | J.-M. Laget | Unitary constraints on Deeply Virtual Compton Scattering | 5 pages, 6 figures | Phys.Rev.C76:052201,2007 | 10.1103/PhysRevC.76.052201 | JLAB-THY-07-702 | hep-ph | null | At moderately low momentum transfer (-t up to 1 GeV^2) the coupling to the
vector meson production channels gives the dominant contribution to real
Compton and deeply virtual Compton scattering (DVCS). Starting from a Regge
Pole approach that successfully describes vector meson production, the singular
part of the corresponding box diagrams (where the intermediate vector
meson-baryon pair propagates on-shell) is evaluated without any further
assumptions (unitarity). Such a treatment explains not only the unexpectedly
large DVCS unpolarized cross section that has been recently measured at
Jefferson Laboratory (JLab), but also all the beam spin and charge asymmetries
that has been measured at JLab and Hermes, without explicit need of Generalized
Parton Distributions (GPD). The issue of the relationship between the two
approaches is addressed.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 11:29:09 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Laget",
"J. -M.",
""
]
] |
0708.1251 | I\~nigo Arregui | Inigo Arregui, Jaume Terradas, Ramon Oliver, Jose Luis Ballester | The resonant damping of fast magnetohydrodynamic oscillations in a
system of two coronal slabs | 25 pages, 9 figures | null | 10.1086/524934 | null | astro-ph | null | Observations of transversal coronal loop oscillations very often show the
excitation and damping of oscillations in groups of coronal loops rather than
in individual and isolated structures. We present results on the oscillatory
properties (periods, damping rates, and spatial distribution of perturbations)
for resonantly damped oscillations in a system of two inhomogeneous coronal
slabs and compare them to the properties found in single slab loop models. A
system of two identical coronal loops is modeled, in Cartesian geometry, as
being composed by two density enhancements. The linear magnetohydrodynamic
(MHD) wave equations for oblique propagation of waves are solved and the
damping of the different solutions, due to the transversal inhomogeneity of the
density profile, is computed. The physics of the obtained results is analyzed
by an examination of the perturbed physical variables. We find that, due to the
interaction between the loops, the normal modes of oscillation present in a
single slab split into symmetric and antisymmetric oscillations when a system
of two identical slabs is considered. The frequencies of these solutions may
differ from the single slab results when the distance between the loops is of
the order of a few slab widths. Oblique propagation of waves weakens this
interaction, since solutions become more confined to the edges of the slabs.
The damping is strong for surface-like oscillations, while sausage body-like
solutions are unaffected. For some solutions, and small slab separations, the
damping in a system of two loops differs substantially from the damping of a
single loop.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 11:32:00 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Arregui",
"Inigo",
""
],
[
"Terradas",
"Jaume",
""
],
[
"Oliver",
"Ramon",
""
],
[
"Ballester",
"Jose Luis",
""
]
] |
0708.1252 | A. K. Chaudhuri | A. K. Chaudhuri | Saturation of elliptic flow and shear viscosity | In the revised version, viscous dynamics predictions for pT spectra
of identified particles are shown. 4 pages, 2 figures | null | null | null | nucl-th | null | Effect of shear viscosity on elliptic flow is studied in causal dissipative
hydrodynamics in 2+1 dimensions. Elliptic flow is reduced in viscous dynamics.
Causal evolution of minimally viscous fluid ($\eta/s$=0.08), can explain the
PHENIX data on elliptic flow in 16-23% Au+Au collisions up to $p_T\approx$3.6
GeV. In contrast, ideal hydrodynamics, can explain the same data only up to
$p_T\approx$1.5 GeV. $p_T$ spectra of identified particles are also better
explained in minimally viscous fluid than in ideal dynamics. However,
saturation of elliptic flow at large $p_T$ is not reproduced.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 14:05:59 GMT"
},
{
"version": "v2",
"created": "Mon, 8 Oct 2007 05:30:49 GMT"
}
] | 2007-10-08T00:00:00 | [
[
"Chaudhuri",
"A. K.",
""
]
] |
0708.1253 | Vladimir S. Gerdjikov | V. S. Gerdjikov (Institute for Nuclear Research and Nuclear Energy,
Bulgarian Academy of Sciences, Sofia, Bulgaria) D. J. Kaup (Department of
Mathematics, University of Central Florida, Orlando, Florida, USA) N. A.
Kostov (Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy
of Sciences, Sofia, Bulgaria), T. I. Valchev (Institute for Nuclear Research
and Nuclear Energy, Bulgarian Academy of Sciences, Sofia, Bulgaria) | How many types of soliton solutions do we know? | LaTeX, 24 pages, no figures | null | null | null | nlin.SI nlin.PS | null | We consider several ways of how one could classify the various types of
soliton solutions related to nonlinear evolution equations which are solvable
by the inverse scattering method. In doing so we make use of the fundamental
analytic solutions, the dressing procedure, the reduction technique and other
tools characteristic for that method.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 12:08:30 GMT"
}
] | 2007-08-10T00:00:00 | [
[
"Gerdjikov",
"V. S.",
"",
"Institute for Nuclear Research and Nuclear Energy,\n Bulgarian Academy of Sciences, Sofia, Bulgaria"
],
[
"Kaup",
"D. J.",
"",
"Department of\n Mathematics, University of Central Florida, Orlando, Florida, USA"
],
[
"Kostov",
"N. A.",
"",
"Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy\n of Sciences, Sofia, Bulgaria"
],
[
"Valchev",
"T. I.",
"",
"Institute for Nuclear Research\n and Nuclear Energy, Bulgarian Academy of Sciences, Sofia, Bulgaria"
]
] |
0708.1254 | Etienne Mann | Barbara Fantechi, Etienne Mann, Fabio Nironi | Smooth toric DM stacks | 37 pages, 4 figures, minor changes, to appear in Crelle | null | null | null | math.AG math.AC | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We give a new definition of smooth toric DM stacks in the same spirit of
toric varieties. We show that our definition is equivalent to the one of
Borisov, Chen and Smith in terms of stacky fans. In particular, we give a
geometric interpretation of the combinatorial data contained in a stacky fan.
We also give a bottom up classification in terms of simplicial toric varieties
and fiber products of root stacks.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 12:50:45 GMT"
},
{
"version": "v2",
"created": "Tue, 22 Sep 2009 18:39:26 GMT"
}
] | 2009-09-22T00:00:00 | [
[
"Fantechi",
"Barbara",
""
],
[
"Mann",
"Etienne",
""
],
[
"Nironi",
"Fabio",
""
]
] |
0708.1255 | Renat Yulmetyev M. | Renat M. Yulmetyev, David E. Valliancourt, Fail M. Gafarov, Sergey A.
Demin, Oleg Yu. Panischev, Peter H\"anggi | Relaxational Singularities of Human Motor System at Aging Due to
Short-Range and Long-Range Time Correlations | 28 pages, 18 figures, Submitted to Nonlinear Phenomena in Complex
Systems, Minsk, Belarus | null | null | null | physics.data-an physics.med-ph | null | In this paper we study the relaxation singularities of human motor system at
aging. Our purpose is to examine the structure of force output variability as a
function of human aging in the time and frequency domains. For analysis of
experimental data we have developed here the statistical theory of relaxation
of force output fluctuation with taking into account the effects of two
relaxation channels. The first of them contains the contribution of short-range
correlation whereas other relaxation component reflects the effect of
long-range correlation. The analysis of experimental data shows, that the
general behavior of relaxation processes at human aging is determined by a
complicated combination and nonlinear interactions two above stated relaxation
processes as a whole.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 12:19:45 GMT"
}
] | 2007-08-10T00:00:00 | [
[
"Yulmetyev",
"Renat M.",
""
],
[
"Valliancourt",
"David E.",
""
],
[
"Gafarov",
"Fail M.",
""
],
[
"Demin",
"Sergey A.",
""
],
[
"Panischev",
"Oleg Yu.",
""
],
[
"Hänggi",
"Peter",
""
]
] |
0708.1256 | Jose-Luis Aragon | J. L\'opez-Sauceda and J.L. Arag\'on | Eutacticity in sea urchin evolution | 17 pages, 6 figures | Bulletin of Mathematical Biology, 70 (2008) 625-634 | 10.1007/s11538-007-9273-2 | null | q-bio.QM | null | An eutactic star, in a n-dimensional space, is a set of N vectors which can
be viewed as the projection of N orthogonal vectors in a N-dimensional space.
By adequately associating a star of vectors to a particular sea urchin we
propose that a measure of the eutacticity of the star constitutes a measure of
the regularity of the sea urchin. Then we study changes of regularity
(eutacticity) in a macroevolutive and taxonomic level of sea urchins belonging
to the Echinoidea Class. An analysis considering changes through geological
time suggests a high degree of regularity in the shape of these organisms
through their evolution. Rare deviations from regularity measured in
Holasteroida order are discussed.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 18:31:07 GMT"
}
] | 2021-11-05T00:00:00 | [
[
"López-Sauceda",
"J.",
""
],
[
"Aragón",
"J. L.",
""
]
] |
0708.1257 | Paolo Battinelli | P. Battinelli, S. Demers, F. Mannucci | The assessment of the near infrared identification of Carbon stars. I.
The Local Group galaxies WLM, IC 10 and NGC 6822 | A&A accepted 18.07.2007 | null | 10.1051/0004-6361:20077760 | null | astro-ph | null | {The selection of AGB C and M stars from NIR colours has been done in recent
years using adjustable criteria that are in needs of standardization if one
wants to compare, in a coherent manner, properties of various populations.} We
intend to assess the NIR colour technique to identify C and M stars. We compare
the NIR colours of several C stars previously identified from spectroscopy or
narrow band techniques in WLM, IC 10 and NGC 6822. We demonstrate that very few
M stars have $(J-K)_0 > 1.4$ but a non negligible number of C stars are bluer
than this limit. Thus, counts of M and C stars based on such limit do not
produce pure samples. C/M ratios determined from NIR colours must be regarded
as underestimates mainly because the M numbers include many warm C stars and
also K stars if no blue limit is considered.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 12:26:33 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Battinelli",
"P.",
""
],
[
"Demers",
"S.",
""
],
[
"Mannucci",
"F.",
""
]
] |
0708.1258 | Valentina D'Odorico | Valentina D'Odorico (for the CODEX/ESPRESSO team) | CODEX/ESPRESSO: the era of precision spectroscopy | 3 pages, 2 figures, to appear in the "Memorie della SAIt",
proceedings of the "LI congresso della Societa' Astronomica Italiana",
Firenze, April 17-20 2007. Reference updated and typos corrected | null | null | null | astro-ph | null | CODEX is a high resolution spectrograph for the European ELT. CODEX is
conceived to reach the highest precision and stability, allowing the execution
of programs spanning many years. Several innovative technical concepts need to
be introduced to reach those excellent characteristics. Thus, the CODEX
consortium has foreseen the realization of a CODEX precursor at the VLT: the
ESPRESSO spectrograph. INAF is strongly committed in the ESPRESSO concept study
both in terms of financial and human resources.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 12:51:16 GMT"
},
{
"version": "v2",
"created": "Mon, 13 Aug 2007 08:43:10 GMT"
}
] | 2019-08-14T00:00:00 | [
[
"D'Odorico",
"Valentina",
"",
"for the CODEX/ESPRESSO team"
]
] |
0708.1259 | Sergey Mozgovoy | Sergey Mozgovoy, Markus Reineke | On the number of stable quiver representations over finite fields | 12 pages | null | null | null | math.RT math.AG | null | We prove a new formula for the generating function of polynomials counting
absolutely stable representations of quivers over finite fields. The case of
irreducible representations is studied in more detail.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 16:11:59 GMT"
}
] | 2007-08-10T00:00:00 | [
[
"Mozgovoy",
"Sergey",
""
],
[
"Reineke",
"Markus",
""
]
] |
0708.1260 | Davor Horvatic | D. Horvatic, D. Klabucar, A. E. Radzhabov | $\eta$ and $\eta'$ mesons in the Dyson-Schwinger approach at finite
temperature | 13 pages, 15 figures | Phys.Rev.D76:096009,2007 | 10.1103/PhysRevD.76.096009 | null | hep-ph | null | We study the temperature dependence of the pseudoscalar meson properties in a
relativistic bound-state approach exhibiting the chiral behavior mandated by
QCD. Concretely, we adopt the Dyson-Schwinger approach with a rank-2 separable
model interaction. After extending the model to the strange sector and fixing
its parameters at zero temperature, T=0, we study the T-dependence of the
masses and decay constants of all ground-state mesons in the pseudoscalar
nonet. Of chief interest are $\eta$ and $\eta^\prime$. The influence of the QCD
axial anomaly on them is successfully obtained through the Witten-Veneziano
relation at T=0. The same approach is then extended to T>0, using lattice QCD
results for the topological susceptibility. The most conspicuous finding is an
increase of the $\eta^\prime$ mass around the chiral restoration temperature
$T_{\rm Ch}$, which would suggest a suppression of $\eta^\prime$ production in
relativistic heavy-ion collisions. The increase of the $\eta^\prime$ mass may
also indicate that the extension of the Witten-Veneziano relation to finite
temperatures becomes unreliable around and above $T_{\rm Ch}$. Possibilities of
an improved treatment are discussed.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 18:26:02 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Horvatic",
"D.",
""
],
[
"Klabucar",
"D.",
""
],
[
"Radzhabov",
"A. E.",
""
]
] |
0708.1261 | Nelson Nunes | E. J. Copeland, D. J. Mulryne, N. J. Nunes, M. Shaeri | Super-inflation in Loop Quantum Cosmology | 11 pages, 2 figures. Extended discussion section | Phys.Rev.D77:023510,2008 | 10.1103/PhysRevD.77.023510 | null | gr-qc | null | We investigate the dynamics of super-inflation in two versions of Loop
Quantum Cosmology, one in which the Friedmann equation is modified by the
presence of inverse volume corrections, and one in which quadratic corrections
are important. Computing the tilt of the power spectrum of the perturbed scalar
field in terms of fast-roll parameters, we conclude that the first case leads
to a power spectrum that is scale invariant for steep power law negative
potentials and for the second case, scale invariance is obtained for positive
potentials that asymptote to a constant value for large values of the scalar
field. It is found that in both cases, the horizon problem is solved with only
a few e-folds of super-inflationary evolution.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 13:01:52 GMT"
},
{
"version": "v2",
"created": "Sat, 6 Oct 2007 20:36:06 GMT"
},
{
"version": "v3",
"created": "Tue, 8 Jan 2008 18:20:22 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Copeland",
"E. J.",
""
],
[
"Mulryne",
"D. J.",
""
],
[
"Nunes",
"N. J.",
""
],
[
"Shaeri",
"M.",
""
]
] |
0708.1262 | Mathijs De Vroome | Mathijs de Vroome | N=2 Supersymmetric Theories, Dyonic Charges and Instantons | 125 pages, 2 tables, based on Ph.D. thesis | null | null | null | hep-th | null | This paper contains the results of our investigations of BPS instantons and
of our work on N=2 supersymmetric gauge theories. The BPS instantons we study
appear in type II string theory compactifications on Calabi-Yau threefolds. In
the corresponding four-dimensional effective supergravity actions the BPS
instantons arise as finite action solutions to the Euclidean equations of
motion. For N=2 supersymmetric gauge theories we construct general Lagrangians
involving gauge groups with (non-abelian) electric and magnetic (dyonic)
charges. In this work a coupling to hypermultiplets is included.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 14:07:42 GMT"
}
] | 2007-08-10T00:00:00 | [
[
"de Vroome",
"Mathijs",
""
]
] |
0708.1263 | David Damanik | Michael Boshernitzan (Rice), David Damanik (Rice) | Generic Continuous Spectrum for Ergodic Schr"odinger Operators | 14 pages | Commun. Math. Phys. 283 (2008), 647-662 | 10.1007/s00220-008-0537-y | null | math.SP math.DS | null | We consider discrete Schr"odinger operators on the line with potentials
generated by a minimal homeomorphism on a compact metric space and a continuous
sampling function. We introduce the concepts of topological and metric
repetition property. Assuming that the underlying dynamical system satisfies
one of these repetition properties, we show using Gordon's Lemma that for a
generic continuous sampling function, the associated Schr"odinger operators
have no eigenvalues in a topological or metric sense, respectively. We present
a number of applications, particularly to shifts and skew-shifts on the torus.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 19:09:58 GMT"
}
] | 2015-05-13T00:00:00 | [
[
"Boshernitzan",
"Michael",
"",
"Rice"
],
[
"Damanik",
"David",
"",
"Rice"
]
] |
0708.1264 | Viktor Toth | J. W. Moffat and V. T. Toth | Testing modified gravity with motion of satellites around galaxies | 4 pages, 2 figures; substantial revision with independent data
analysis | null | null | null | astro-ph gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A modified gravity (MOG) theory, that has been successfully fitted to galaxy
rotational velocity data, cluster data, the Bullet Cluster 1E0657-56 and
cosmological observations, is shown to be in good agreement with the motion of
satellite galaxies around host galaxies at distances 50-400 kpc.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 16:40:46 GMT"
},
{
"version": "v2",
"created": "Mon, 27 Aug 2007 19:00:47 GMT"
},
{
"version": "v3",
"created": "Tue, 29 Jan 2008 23:47:31 GMT"
},
{
"version": "v4",
"created": "Mon, 5 May 2008 22:50:22 GMT"
},
{
"version": "v5",
"created": "Sun, 10 Aug 2008 17:01:12 GMT"
}
] | 2008-08-10T00:00:00 | [
[
"Moffat",
"J. W.",
""
],
[
"Toth",
"V. T.",
""
]
] |
0708.1265 | Aneta Siemiginowska | Aneta Siemiginowska (1), Thomas L. Aldcroft (1), Doug Burke (1), Jill
Bechtold (2), C.C. Cheung (3,4), Stephanie LaMassa (5), Diana M. Worrall (6)
((1) Center for Astrphysics, Cambridge, MA; (2) Steward Observatory,
University of Arizona, Tucson, AZ; (3) KIPAC, Stanford, CAl; (4) Jansky
Postdoctoral Fellow of the National Radio Astronomy Observatory; (5) Johns
Hopkins University, Baltimore, MD; (6) Department of Physics, University of
Bristol, Tyndall Ave., Bristol, UK) | Evolution of a Powerful Radio Loud Quasar 3C186 and its Impact on the
Cluster Environment at z=1 | 7 pages, 5 figures. To be published in the proceedings of
"Extragalactic Jets: Theory and Observation from Radio to Gamma Ray" ASP
Conference Series, T. A. Rector and D. S. De Young (eds.) | null | null | null | astro-ph | null | X-ray cluster emission has been observed mainly in clusters with "inactive"
cD galaxies (L_bol ~1E40-1E43erg/sec), which do not show signs of accretion
onto a SMBH. Our recent Chandra discovery of ~100kpc scale diffuse X-ray
emission revealed the presence of an X-ray cluster associated with the radio
loud quasar 3C186 at redshift z=1.1 and suggests interactions between the
quasar and the cluster. In contrast to the majority of X-ray clusters the 3C186
cluster contains a quasar in the center whose radiative power alone exceeds
that which would be needed to quench the cluster cooling. We present the
Chandra X-ray data and new deep radio and optical images of this cluster. The
3C186 quasar is a powerful Compact Steep Spectrum radio source expanding into
the cluster medium. The 2arcsec radio jet is unresolved in the Chandra
observation, but its direction is orthogonal to the elliptical surface
brightness of the cluster. The radio data show the possible presence of old
radio lobes on 10 arcsec scale in the direction of the radio jet. We discuss
the nature of this source in the context of intermittent radio activity and the
interaction of the young expanding radio source with the cluster medium.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 16:46:57 GMT"
}
] | 2007-08-10T00:00:00 | [
[
"Siemiginowska",
"Aneta",
""
],
[
"Aldcroft",
"Thomas L.",
""
],
[
"Burke",
"Doug",
""
],
[
"Bechtold",
"Jill",
""
],
[
"Cheung",
"C. C.",
""
],
[
"LaMassa",
"Stephanie",
""
],
[
"Worrall",
"Diana M.",
""
]
] |
0708.1266 | Mariano Zimmler | Mariano A. Zimmler, Jiming Bao, Ilan Shalish, Wei Yi, Joonah Yoon,
Venkatesh Narayanamurti and Federico Capasso | Electroluminescence from single nanowires by tunnel injection: an
experimental study | 6 pages, 6 figures | Nanotechnology 18 (2007) 235205 | 10.1088/0957-4484/18/23/235205 | null | cond-mat.other | null | We present a hybrid light-emitting diode structure composed of an n-type
gallium nitride nanowire on a p-type silicon substrate in which current is
injected along the length of the nanowire. The device emits ultraviolet light
under both bias polarities. Tunnel-injection of holes from the p-type substrate
(under forward bias) and from the metal (under reverse bias) through thin
native oxide barriers consistently explains the observed electroluminescence
behaviour. This work shows that the standard p-n junction model is generally
not applicable to this kind of device structure.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 13:28:29 GMT"
}
] | 2007-08-10T00:00:00 | [
[
"Zimmler",
"Mariano A.",
""
],
[
"Bao",
"Jiming",
""
],
[
"Shalish",
"Ilan",
""
],
[
"Yi",
"Wei",
""
],
[
"Yoon",
"Joonah",
""
],
[
"Narayanamurti",
"Venkatesh",
""
],
[
"Capasso",
"Federico",
""
]
] |
0708.1267 | Elizabeth Dan-Cohen | Elizabeth Dan-Cohen | Borel subalgebras of root-reductive Lie algebras | 21 pages | J. Lie Theory 18 (2008) 215-241 | 10.1063/1.2920734 | null | math.RT | null | This paper generalizes the classification in a paper of Dimitrov and Penkov
of Borel subalgebras of gl_infty. Root-reductive Lie algebras are direct limits
of finite-dimensional reductive Lie algebras along inclusions preserving the
root spaces with respect to nested Cartan subalgebras. A Borel subalgebra of a
root-reductive Lie algebra is by definition a maximal locally solvable
subalgebra. The main general result of this paper is that a Borel subalgebra of
an infinite-dimensional indecomposable root-reductive Lie algebra is the
simultaneous stabilizer of a certain type of generalized flag in each of the
standard representations. For the three infinite-dimensional simple
root-reductive Lie algebras more precise results are obtained. The map sending
a maximal closed (isotropic) generalized flag in the standard representation to
its stabilizer hits Borel subalgebras, yielding a bijection in the cases of
sl_infty and sp_infty; in the case of so_infty the fibers are of size one and
two. A description is given of a nice class of toral subalgebras contained in
any Borel subalgebra. Finally, certain Borel subalgebras of a general
root-reductive Lie algebra are seen to correspond bijectively with Borel
subalgebras of the commutator subalgebra, which are understood in terms of the
special cases.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 19:57:46 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Dan-Cohen",
"Elizabeth",
""
]
] |
0708.1268 | Alessio Marrani | S. Ferrara, A. Marrani | Black Hole Attractors in Extended Supergravity | 1+12 pages, 2 figures, Contribution to the Proceedings of PASCOS
2007,13th International Symposium on Particles, Strings and Cosmology,2-7
July 2007, Imperial College, London, UK, to be published online by the
American Institute of Physics; v2: minor improvements, typos fixed, Ref.
added | AIPConf.Proc.957:58-68,2007 | 10.1063/1.2823828 | CERN-PH-TH/2007-140 | hep-th | null | We review some aspects of the attractor mechanism for extremal black holes of
(not necessarily supersymmetric) theories coupling Einstein gravity to scalars
and Maxwell vector fields. Thence, we consider N=2 and N=8, d=4 supergravities,
reporting some recent advances on the moduli spaces associated to BPS and
non-BPS attractor solutions supported by charge orbits with non-compact
stabilizers.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 14:40:48 GMT"
},
{
"version": "v2",
"created": "Thu, 30 Aug 2007 15:33:41 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Ferrara",
"S.",
""
],
[
"Marrani",
"A.",
""
]
] |
0708.1269 | Derek Krepski | Derek Krepski | Pre-quantization of the Moduli Space of Flat G-Bundles over a Surface | 28 pages, 1 table, new version contains minor corrections, to be
published in Journal of Geometry and Physics | null | 10.1016/j.geomphys.2008.07.009 | null | math.SG math.AT | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | For a simply connected, compact, simple Lie group G, the moduli space of flat
G-bundles over a closed surface is known to be pre-quantizable at integer
levels. For non-simply connected G, however, integrality of the level is not
sufficient for pre-quantization, and this paper determines the obstruction --
namely a certain cohomology class in H^3(G^2;Z) -- that places further
restrictions on the underlying level. The levels that admit a pre-quantization
of the moduli space are determined explicitly for all non-simply connected,
compact, simple Lie groups G.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 13:41:25 GMT"
},
{
"version": "v2",
"created": "Mon, 29 Sep 2008 19:58:43 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Krepski",
"Derek",
""
]
] |
0708.1270 | Ashoke Sen | Ashoke Sen | Black Hole Entropy Function, Attractors and Precision Counting of
Microstates | LaTeX file, 196 pages, based on lectures given at various schools;
v2: added appendix E containing analysis of the multiple D5-brane system,
expanded discussion on duality orbits, other minor changes, references added;
v3: equations (5.6.20) and (5.6.21) corrected; v4: minor corrections to
equations (C.19), (C.20) | Gen.Rel.Grav.40:2249-2431,2008 | 10.1007/s10714-008-0626-4 | null | hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In these lecture notes we describe recent progress in our understanding of
attractor mechanism and entropy of extremal black holes based on the entropy
function formalism. We also describe precise computation of the microscopic
degeneracy of a class of quarter BPS dyons in N=4 supersymmetric string
theories, and compare the statistical entropy of these dyons, expanded in
inverse powers of electric and magnetic charges, with a similar expansion of
the corresponding black hole entropy. This comparison is extended to include
the contribution to the entropy from multi-centered black holes as well.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 17:17:05 GMT"
},
{
"version": "v2",
"created": "Sun, 26 Aug 2007 17:35:26 GMT"
},
{
"version": "v3",
"created": "Tue, 6 Nov 2007 18:05:28 GMT"
},
{
"version": "v4",
"created": "Thu, 5 Nov 2009 20:58:13 GMT"
}
] | 2010-04-06T00:00:00 | [
[
"Sen",
"Ashoke",
""
]
] |
0708.1271 | Raji Heyrovska | Raji Heyrovska | Atomic Structures of the Molecular Components in DNA and RNA based on
Bond Lengths as Sums of Atomic Radii | 13 pages including 3 tables and 5 figures; replaced by paper: 12
pages including 3 tables and 5 (improved) figures; replaced by paper: 13
pages with enlarged Table 3 and improved figure 3 (submitted to Open
Structural Biology Journal); replaced by paper: 14 pages with added Figs. 2A
and 6 | The Open Structural Biology Journal, 2008 (2) 1-7. | 10.2174/1874199100802010001 | null | physics.gen-ph physics.chem-ph | null | The interpretation by the author in recent years of bond lengths as sums of
the relevant atomic or ionic radii has been extended here to the bonds in the
skeletal structures of adenine, guanine, thymine, cytosine, uracil, ribose,
deoxyribose and phosphoric acid. On examining the bond length data in the
literature, it has been found that the averages of the bond lengths are close
to the sums of the corresponding atomic covalent radii of carbon, nitrogen,
oxygen, hydrogen and phosphorus. Thus, the conventional molecular structures
have been resolved here, for the first time, into probable atomic structures.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 13:43:47 GMT"
},
{
"version": "v2",
"created": "Tue, 28 Aug 2007 15:00:50 GMT"
},
{
"version": "v3",
"created": "Thu, 11 Oct 2007 13:29:49 GMT"
},
{
"version": "v4",
"created": "Fri, 9 Nov 2007 16:29:47 GMT"
}
] | 2008-03-14T00:00:00 | [
[
"Heyrovska",
"Raji",
""
]
] |
0708.1272 | Alexander Donkov | A. Donkov and A. V. Chubukov | Spin-wave spectra of a kagome stripe | 6 pages, 9 figures, submitted to Europhys. Lett | null | 10.1209/0295-5075/80/67005 | null | cond-mat.str-el | null | We study ground state degeneracy and spin-wave excitations in a 1D version of
a Kagome antiferromagnet -- a Heisenberg antiferromagnet on a Kagome stripe. We
show that for nearest-neighbor interaction, the classical ground state is
infinitely degenerate. For any spin configuration from the degenerate set, the
classical spin-wave spectrum contains, in addition to Goldstone modes, a branch
of zero energy excitations, and a zero mode in another branch. We demonstrate
that the interactions beyond nearest neighbors lift the degeneracy, eliminate a
zero mode, and give a finite dispersion to formerly zero-energy branch, leaving
only Goldstone modes as zero-energy excitations.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 13:48:42 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Donkov",
"A.",
""
],
[
"Chubukov",
"A. V.",
""
]
] |
0708.1273 | Daan Krammer | Daan Krammer | Generalisations of the Tits representation | 21 pages, 6 figures | null | null | null | math.CO | null | We construct a group K_n with properties similar to infinite Coxeter groups.
In particular, it has a geometric representation featuring hyperplanes and
simplicial chambers. The generators of K_n are given by 2-element subsets of
{0, .., n}. We give some easy combinatorial results on the finite residues of
K_n.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 13:50:24 GMT"
}
] | 2007-08-10T00:00:00 | [
[
"Krammer",
"Daan",
""
]
] |
0708.1274 | Rikard Nelander | R. Nelander, A. Wacker, M. F. Pereira Jr., D. G. Revin, M. R. Soulby,
L. R. Wilson, J. W. Cockburn, A. B. Krysa, J. S. Roberts, R. J. Airey | Fingerprints of spatial charge transfer in Quantum Cascade Lasers | 6 pages, 5 figures | J. Appl. Phys. 102, 113104 (2007) | 10.1063/1.2817471 | null | cond-mat.mes-hall | null | We show that mid infrared transmission spectroscopy of a quantum cascade
laser provides clear cut information on changes in charge location at different
bias. Theoretical simulations of the evolution of the gain/absorption spectrum
for the $\lambda \sim$ 7.4 $\mu$m InGaAs/AlInAs/InP quantum cascade laser have
been compared with the experimental findings. Transfer of electrons between the
ground states in the active region and the states in the injector goes in hand
with a decrease of discrete intersubband absorption peaks and an increase of
broad high-energy absorption towards the continuum delocalised states above the
barriers.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 13:56:03 GMT"
}
] | 2007-12-05T00:00:00 | [
[
"Nelander",
"R.",
""
],
[
"Wacker",
"A.",
""
],
[
"Pereira",
"M. F.",
"Jr."
],
[
"Revin",
"D. G.",
""
],
[
"Soulby",
"M. R.",
""
],
[
"Wilson",
"L. R.",
""
],
[
"Cockburn",
"J. W.",
""
],
[
"Krysa",
"A. B.",
""
],
[
"Roberts",
"J. S.",
""
],
[
"Airey",
"R. J.",
""
]
] |
0708.1275 | Philip Lucas | F. C. Riddick (1,2), P. F. Roche (2), P. W. Lucas (3) ((1) Penn State
University, (2) University of Oxford, (3) University of Hertfordshire) | Optical Spectroscopic Classification and Membership of Young M Dwarfs in
Star-Forming Regions | 11 pages, accepted by MNRAS | null | 10.1111/j.1365-2966.2007.12309.x | null | astro-ph | null | The spectral type is a key parameter in calibrating the temperature which is
required to estimate the mass of young stars and brown dwarfs. We describe an
approach developed to classify low-mass stars and brown dwarfs in the Trapezium
Cluster using red optical spectra, which can be applied to other star-forming
regions. The classification uses two methods for greater accuracy: the use of
narrowband spectral indices which rely on the variation of the strength of
molecular lines with spectral type and a comparison with other previously
classified young, low-mass objects in the Chamaeleon I star-forming region. We
have investigated and compared many different molecular indices and have
identified a small number of indices which work well for classifying M-type
objects in nebular regions. The indices are calibrated for young, pre-main
sequence objects whose spectra are affected by their lower surface gravities
compared with those on the main sequence. Spectral types obtained are
essentially independent of both reddening and nebular emission lines.
Confirmation of candidate young stars and brown dwarfs as bona fide cluster
members may be accomplished with moderate resolution spectra in the optical
region by an analysis of the strength of the gravity-sensitive Na doublet. It
has been established that this feature is much weaker in these very young
objects than in field dwarfs. A sodium spectral index is used to estimate the
surface gravity and to demonstrate quantitatively the difference between young
(1-2Myr) objects, and dwarf and giant field stars.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 13:57:38 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Riddick",
"F. C.",
""
],
[
"Roche",
"P. F.",
""
],
[
"Lucas",
"P. W.",
""
]
] |
0708.1276 | Olivier Lavialle | Olivier Lavialle (IMS), Sorin Pop (IMS), Christian Germain (IMS), Marc
Donias (IMS), Sebastien Guillon, Naamen Keskes, Yannick Berthoumieu (IMS) | Seismic Fault Preserving Diffusion | 10 pages | Journal of Applied Geophysics 2007, 61 (2007) 132-141 | 10.1016/j.jappgeo.2006.06.002 | null | physics.geo-ph | null | This paper focuses on the denoising and enhancing of 3-D reflection seismic
data. We propose a pre-processing step based on a non linear diffusion
filtering leading to a better detection of seismic faults. The non linear
diffusion approaches are based on the definition of a partial differential
equation that allows us to simplify the images without blurring relevant
details or discontinuities. Computing the structure tensor which provides
information on the local orientation of the geological layers, we propose to
drive the diffusion along these layers using a new approach called SFPD
(Seismic Fault Preserving Diffusion). In SFPD, the eigenvalues of the tensor
are fixed according to a confidence measure that takes into account the
regularity of the local seismic structure. Results on both synthesized and real
3-D blocks show the efficiency of the proposed approach.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 16:54:13 GMT"
}
] | 2007-08-10T00:00:00 | [
[
"Lavialle",
"Olivier",
"",
"IMS"
],
[
"Pop",
"Sorin",
"",
"IMS"
],
[
"Germain",
"Christian",
"",
"IMS"
],
[
"Donias",
"Marc",
"",
"IMS"
],
[
"Guillon",
"Sebastien",
"",
"IMS"
],
[
"Keskes",
"Naamen",
"",
"IMS"
],
[
"Berthoumieu",
"Yannick",
"",
"IMS"
]
] |
0708.1277 | Richard D. Ball | Richard D Ball | Resummation of Hadroproduction Cross-sections at High Energy | 49 pages, 25 figures, version to be published in Nucl Phys B | Nucl.Phys.B796:137-183,2008 | 10.1016/j.nuclphysb.2007.12.014 | CERN-PH-TH/2007-212, Edinburgh 2007-11 | hep-ph | null | We reconsider the high energy resummation of photoproduction,
electroproduction and hadroproduction cross-sections, in the light of recent
progress in the resummation of perturbative parton evolution to NLO in
logarithms of Q^2 and x. We show in particular that the when the coupling runs
the dramatic enhancements seen at fixed coupling, due to infrared singularities
in the partonic cross-sections, are substantially reduced, to the extent that
they are largely accounted for by the usual NLO and NNLO perturbative
corrections. This leads to a novel explanation of the large K-factors commonly
found in perturbative calculations of hadroproduction cross-sections. We give
numerical estimates of high energy resummation effects for inclusive
B-production, inclusive jets, Drell-Yan and vector boson production, along with
their rapidity distributions. We find that resummation modifies the
B-production cross-section at the LHC by at most 15%, but that the enhancement
of gluonic W-production may be as large as 50% at large rapidities.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 17:07:15 GMT"
},
{
"version": "v2",
"created": "Sat, 8 Dec 2007 22:22:55 GMT"
}
] | 2010-03-25T00:00:00 | [
[
"Ball",
"Richard D",
""
]
] |
0708.1278 | Mariano Zimmler | Mariano A. Zimmler, Jiming Bao, Ilan Shalish, Wei Yi, Venkatesh
Narayanamurti and Federico Capasso | A two-colour heterojunction unipolar nanowire light-emitting diode by
tunnel injection | 9 pages, 11 figures | Nanotechnology 18 (2007) 395201 | 10.1088/0957-4484/18/39/395201 | null | cond-mat.other | null | We present a systematic study of the current-voltage characteristics and
electroluminescence of gallium nitride (GaN) nanowire on silicon (Si) substrate
heterostructures where both semiconductors are n-type. A novel feature of this
device is that by reversing the polarity of the applied voltage the
luminescence can be selectively obtained from either the nanowire or the
substrate. For one polarity of the applied voltage, ultraviolet (and visible)
light is generated in the GaN nanowire, while for the opposite polarity
infrared light is emitted from the Si substrate. We propose a model, which
explains the key features of the data, based on electron tunnelling from the
valence band of one semiconductor into the conduction band of the other
semiconductor. For example, for one polarity of the applied voltage, given a
sufficient potential energy difference between the two semiconductors,
electrons can tunnel from the valence band of GaN into the Si conduction band.
This process results in the creation of holes in GaN, which can recombine with
conduction band electrons generating GaN band-to-band luminescence. A similar
process applies under the opposite polarity for Si light emission. This device
structure affords an additional experimental handle to the study of
electroluminescence in single nanowires and, furthermore, could be used as a
novel approach to two-colour light-emitting devices.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 14:00:28 GMT"
},
{
"version": "v2",
"created": "Tue, 4 Sep 2007 12:38:15 GMT"
}
] | 2007-09-04T00:00:00 | [
[
"Zimmler",
"Mariano A.",
""
],
[
"Bao",
"Jiming",
""
],
[
"Shalish",
"Ilan",
""
],
[
"Yi",
"Wei",
""
],
[
"Narayanamurti",
"Venkatesh",
""
],
[
"Capasso",
"Federico",
""
]
] |
0708.1279 | Jiri Krticka | Jiri Krticka, Joachim Puls, Jiri Kubat | The influence of clumping on predicted O star wind parameters | 3 pages, to appear in the proceedings of workshop 'Clumping in Hot
Star Winds', eds. W.-R. Hamann, A. Feldmeier, & L. Oskinova | null | null | null | astro-ph | null | We study the influence of clumping on the predicted wind structure of O-type
stars. For this purpose we artificially include clumping into our stationary
wind models. When the clumps are assumed to be optically thin, the radiative
line force increases compared to corresponding unclumped models, with a similar
effect on either the mass-loss rate or the terminal velocity (depending on the
onset of clumping). Optically thick clumps, alternatively, might be able to
decrease the radiative force.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 17:03:59 GMT"
}
] | 2007-08-10T00:00:00 | [
[
"Krticka",
"Jiri",
""
],
[
"Puls",
"Joachim",
""
],
[
"Kubat",
"Jiri",
""
]
] |
0708.1280 | Philip Lucas | F. C. Riddick (1,2), P. F. Roche (2), P. W. Lucas (3) ((1) Penn State
University, (2) University of Oxford, (3) University of Hertfordshire) | An optical spectroscopic H-R diagram for low-mass stars and brown dwarfs
in Orion | 19 pages, accepted by MNRAS | null | 10.1111/j.1365-2966.2007.12308.x | null | astro-ph | null | The masses and temperatures of young low mass stars and brown dwarfs in star-
forming regions are not yet well established because of uncertainties in the
age of individual objects and the spectral type vs. temperature scale
appropriate for objects with ages of only a few Myr. Using multi-object optical
spectroscopy, 45 low-mass stars and brown dwarfs in the Trapezium Cluster in
Orion have been classified and 44 of these confirmed as bona fide cluster
members. The spectral types obtained have been converted to effective
temperatures using a temperature scale intermediate between those of dwarfs and
giants, which is suitable for young pre-main sequence objects. The objects have
been placed on an H-R diagram overlaid with theoretical isochrones. The low
mass stars and the higher mass substellar objects are found to be clustered
around the 1 Myr isochrone, while many of the lower mass substellar objects are
located well above this isochrone. An average age of 1 Myr is found for the
majority of the objects. Assuming coevality of the sources and an average age
of 1 Myr, the masses of the objects have been estimated and range from 0.018 to
0.44Msun. The spectra also allow an investigation of the surface gravity of the
objects by measurement of the sodium doublet equivalent width. With one
possible exception, all objects have low gravities, in line with young ages,
and the Na indices for the Trapezium objects lie systematically below those of
young stars and brown dwarfs in Chamaeleon, suggesting that the 820 nm Na index
may provide a sensitive means of estimating ages in young clusters.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 14:05:21 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Riddick",
"F. C.",
""
],
[
"Roche",
"P. F.",
""
],
[
"Lucas",
"P. W.",
""
]
] |
0708.1281 | Richard Hill | Jeffrey A. Harvey, Christopher T. Hill and Richard J. Hill | Anomaly mediated neutrino-photon interactions at finite baryon density | 4 pages, 2 figures; references added | Phys.Rev.Lett.99:261601,2007 | 10.1103/PhysRevLett.99.261601 | EFI Preprint 07-21, FERMILAB-Pub-07/401-T | hep-ph astro-ph hep-th nucl-ex nucl-th | null | We propose new physical processes based on the axial vector anomaly and
described by the Wess-Zumino-Witten term that couples the photon, Z-boson, and
the omega-meson. The interaction takes the form of a pseudo-Chern-Simons term,
$\sim \epsilon_{\mu\nu\rho\sigma}\omega^\mu Z^\nu F^{\rho\sigma}$. This term
induces neutrino-photon interactions at finite baryon density via the coupling
of the Z-boson to neutrinos. These interactions may be detectable in various
laboratory and astrophysical arenas. The new interactions may account for the
MiniBooNE excess. They also produce a competitive contribution to neutron star
cooling at temperatures >10^9 K. These processes and related axion--photon
interactions at finite baryon density appear to be relevant in many
astrophysical regimes.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 19:33:14 GMT"
},
{
"version": "v2",
"created": "Sun, 19 Aug 2007 14:52:46 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Harvey",
"Jeffrey A.",
""
],
[
"Hill",
"Christopher T.",
""
],
[
"Hill",
"Richard J.",
""
]
] |
0708.1282 | Stephen King | Stefan Antusch, Stephen F. King, Michal Malinsky | Solving the SUSY Flavour and CP Problems with SU(3) Family Symmetry | 56 pages; discussion extended, references added; version published in
JHEP | JHEP 0806:068,2008 | 10.1088/1126-6708/2008/06/068 | null | hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We show how the SUSY flavour and CP problems can be solved using gauged SU(3)
family symmetry previously introduced to describe quark and lepton masses and
mixings, in particular neutrino tri-bimaximal mixing via constrained sequential
dominance. The Yukawa and soft trilinear and scalar mass squared matrices and
kinetic terms are expanded in powers of the flavons used to spontaneously break
the SU(3) family symmetry, and the canonically normalized versions of these
matrices are constructed. The soft mass matrices are then expressed in the
Super-CKM basis, and the leading order mass insertion parameters are
calculated, and are shown to satisfy the experimental constraints from flavour
changing neutral current processes. Assuming that CP is spontaneously broken by
the flavons, the next-to-leading order effects responsible for CP violation are
then estimated, and the predictions for electric dipole moments are shown to be
an order of magnitude more suppressed than those predicted from the constrained
minimal supersymmetric standard model (CMSSM), and may be further suppressed if
the high energy trilinear soft parameter is assumed to be relatively small. We
also predict that, unlike in the CMSSM, epsilon_K'/epsilon_K may be dominated
by the SUSY operator O_8. We also discuss the additional constraints from
unification, which can lead to further predictions for flavour changing in our
scheme.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 17:08:44 GMT"
},
{
"version": "v2",
"created": "Mon, 8 Oct 2007 10:58:44 GMT"
},
{
"version": "v3",
"created": "Mon, 3 Mar 2008 11:18:12 GMT"
},
{
"version": "v4",
"created": "Mon, 14 Jul 2008 14:15:56 GMT"
}
] | 2009-01-06T00:00:00 | [
[
"Antusch",
"Stefan",
""
],
[
"King",
"Stephen F.",
""
],
[
"Malinsky",
"Michal",
""
]
] |
0708.1283 | Bernard S. Kay | Bernard S. Kay and Peter Larkin (York) | Pre-Holography | 6 pages, 1 eps figure, revtex. v3: Improved figure. Error corrected
in Endnote [14]; the new version of Endnote [14] points out the, in general,
unusual "localization" of the boundary fields. Other minor improvements and
clarifications. v3 to appear in Physical Review D (Rapid Communications) | Phys.Rev.D77:121501,2008 | 10.1103/PhysRevD.77.121501 | null | hep-th gr-qc math-ph math.MP | null | We construct a symplectic isomorphism, h, from classical Klein Gordon
solutions of mass m on (d+1)-dimensional Lorentzian Anti de Sitter space
(equipped with the usual symplectic form) to a certain symplectic space of
functions on its conformal boundary (only) for all integer and half-integer
Delta (= d/2 + (1/2)(d^2 + 4m^2)^{1/2}). h induces a large family of new
examples of Rehren's algebraic holography in which the net of local quantum
Klein Gordon algebras in AdS is seen to map to a suitably defined net of local
algebras for the (generalized free) scalar conformal field with anomalous
dimension Delta on d-dimensional Minkowski space (the AdS boundary). Relatedly,
we show for these models that Bertola et al's boundary-limit holography becomes
a quantum duality (only) if the test functions for boundary Wightman
distributions are restricted in a particular way.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 14:09:25 GMT"
},
{
"version": "v2",
"created": "Mon, 10 Sep 2007 18:34:05 GMT"
},
{
"version": "v3",
"created": "Fri, 16 May 2008 16:41:16 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Kay",
"Bernard S.",
"",
"York"
],
[
"Larkin",
"Peter",
"",
"York"
]
] |
0708.1284 | Marc Chemtob | M. Chemtob, P.N. Pandita | Implications of vacuum stability constraints on the nonminimal
supersymmetric standard model with lepton number violation | 39 pages, 5 figures, Latex file, ps figures | Phys.Rev.D76:095019,2007 | 10.1103/PhysRevD.76.095019 | null | hep-ph | null | We carry out a detailed analysis of the scalar sector of the nonminimal
supersymmetric standard model with lepton number violation, and study the
constraints imposed on it by the stability of the electroweak symmetry breaking
vacuum. The model contains a trilinear lepton mumber violating term in the
superpotential together with the associated \susy breaking interactions which
can give rise to neutrino masses. We evaluate the mass matrices for the various
boson and fermion modes and then discuss the effect that the lepton number
violating interactions have on the mass spectra using a phenomenological
precription to implement the experimental constraints on the light neutrinos
mass matrix. We also discuss qualitatively the conditions on the lepton number
violating parameters set by the unbounded from below directions, and from the
absence of the charge and color breaking minima in this model.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 17:29:00 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Chemtob",
"M.",
""
],
[
"Pandita",
"P. N.",
""
]
] |
0708.1285 | Sanefumi Moriyama | Takuya Matsumoto, Sanefumi Moriyama, Alessandro Torrielli | A Secret Symmetry of the AdS/CFT S-matrix | 12 pages, no figures, v2: reference added, version to appear in JHEP | JHEP 0709:099,2007 | 10.1088/1126-6708/2007/09/099 | MIT-CTP-3853 | hep-th | null | We find a new quantum Yangian symmetry of the AdS/CFT S-matrix, which
complements the original su(2|2) symmetry to gl(2|2) and does not have a Lie
algebra analog. Our finding is motivated by the Yangian double structure
discovered at the classical level.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 17:49:25 GMT"
},
{
"version": "v2",
"created": "Wed, 19 Sep 2007 15:34:38 GMT"
}
] | 2009-06-11T00:00:00 | [
[
"Matsumoto",
"Takuya",
""
],
[
"Moriyama",
"Sanefumi",
""
],
[
"Torrielli",
"Alessandro",
""
]
] |
0708.1286 | Colleen Robles | Colleen Robles and Sema Salur | Calibrated associative and Cayley embeddings | null | null | null | null | math.DG math.AG | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Using the Cartan-Kahler theory, and results on real algebraic structures, we
prove two embedding theorems. First, the interior of a smooth, compact
3-manifold may be isometrically embedded into a G_2-manifold as an associative
submanifold. Second, the interior of a smooth, compact 4-manifold K, whose
double has a trivial bundle of self-dual 2-forms, may be isometrically embedded
into a Spin(7)-manifold as a Cayley submanifold. Along the way, we also show
that Bochner's Theorem on real analytic approximation of smooth differential
forms, can be obtained using real algebraic tools developed by Akbulut and
King.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 18:05:46 GMT"
},
{
"version": "v2",
"created": "Thu, 8 Oct 2009 20:38:46 GMT"
}
] | 2009-10-08T00:00:00 | [
[
"Robles",
"Colleen",
""
],
[
"Salur",
"Sema",
""
]
] |
0708.1287 | Sefi Ladkani | Sefi Ladkani | Universal derived equivalences of posets of tilting modules | 11 pages | null | null | null | math.RT | null | We show that for two quivers without oriented cycles related by a BGP
reflection, the posets of their tilting modules are related by a simple
combinatorial construction, which we call flip-flop.
We deduce that the posets of tilting modules of derived equivalent path
algebras of quivers without oriented cycles are universally derived equivalent.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 18:11:13 GMT"
}
] | 2007-08-10T00:00:00 | [
[
"Ladkani",
"Sefi",
""
]
] |
0708.1288 | Martin Horvat | Martin Horvat and Tomaz Prosen | Dynamical approach to chains of scatterers | 16 pages, 7 figures | null | 10.1088/1751-8113/40/38/010 | null | quant-ph | null | Linear chains of quantum scatterers are studied in the process of
lengthening, which is treated and analysed as a discrete dynamical system
defined over the manifold of scattering matrices. Elementary properties of such
dynamics relate the transport through the chain to the spectral properties of
individual scatterers. For a single-scattering channel case some new light is
shed on known transport properties of disordered and noisy chains, whereas
translationally invariant case can be studied analytically in terms of a simple
deterministic dynamical map. The many-channel case was studied numerically by
examining the statistical properties of scatterers that correspond to a certain
type of transport of the chain i.e. ballistic or (partially) localised.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 14:12:47 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Horvat",
"Martin",
""
],
[
"Prosen",
"Tomaz",
""
]
] |
0708.1289 | Ary Rodriguez-Gonzalez ary | Ary Rodr\'iguez-Gonz\'alez, J. Cant\'o, A. Esquivel, A.C. Raga, P.F.
Velazquez | Winds from clu\sters with non-uniform stellar distributions | 10 pages, 11 figures. MNRAS - Accepted 2007 June 29. Received 2007
June 28; in original form 2007 May 23 | null | 10.1111/j.1365-2966.2007.12167.x | mnr_12167 | astro-ph | null | We present analytic and numerical models of the `cluster wind' resulting from
the multiple interactions of the winds ejected by the stars of a dense cluster
of massive stars. We consider the case in which the distribution of stars
(i.e., the number of stars per unit volume) within the cluster is spherically
symmetric, has a power-law radial dependence, and drops discontinuously to zero
at the outer radius of the cluster. We carry out comparisons between an
analytic model (in which the stars are considered in terms of a spatially
continuous injection of mass and energy) and 3D gasdynamic simulations (in
which we include 100 stars with identical winds, located in 3D space by
statistically sampling the stellar distribution function). From the analytic
model, we find that for stellar distributions with steep enough radial
dependencies the cluster wind flow develops a very high central density and a
non-zero central velocity, and for steeper dependencies it becomes fully
supersonic throughout the volume of the cluster (these properties are partially
reproduced by the 3D numerical simulations). Therefore, the wind solutions
obtained for stratified clusters can differ dramatically from the case of a
homogeneous stellar distribution (which produces a cluster wind with zero
central velocity, and a fully subsonic flow within the cluster radius).
Finally, from our numerical simulations we compute predictions of X-ray
emission maps and luminosities, which can be directly compared with
observations of cluster wind flows.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 18:15:54 GMT"
}
] | 2007-08-10T00:00:00 | [
[
"Rodríguez-González",
"Ary",
""
],
[
"Cantó",
"J.",
""
],
[
"Esquivel",
"A.",
""
],
[
"Raga",
"A. C.",
""
],
[
"Velazquez",
"P. F.",
""
]
] |
0708.1290 | Vladimir Manuilov | Vladimir Manuilov, Chao You | On Almost Representations of Property (T) Groups | 10 pages, minor changes, references added | null | null | null | math.OA math.GR | null | Property (T) for groups means a dichotomy: a representation either has an
invariant vector or all vectors are far from being invariant. We show that,
under a stronger condition of A.Zuk, a similar dichotomy holds for almost
representations as well.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 18:16:35 GMT"
},
{
"version": "v2",
"created": "Sun, 12 Aug 2007 17:14:19 GMT"
}
] | 2007-08-12T00:00:00 | [
[
"Manuilov",
"Vladimir",
""
],
[
"You",
"Chao",
""
]
] |
0708.1291 | Zhe Qu | Zhe Qu, Leonard Spinu, Huiqiu Yuan, Vladimir Dobrosavljevic, Wei Bao,
Jeffrey W. Lynn, M. Nicklas, Jin Peng, Tijiang Liu, David Fobes, Etienne
Flesch, and Z. Q. Mao | Unusual heavy-mass nearly ferromagnetic state with a surprisingly large
Wilson ratio in the double layered ruthenates
(Sr$_{1-x}$Ca$_{x}$)$_{3}$Ru$_{2}$O$_{7}$ | 4 pages, 4 figures; to be published in Physical Review B Rapid
Communication; solve the problem with Fig.1 | Phys. Rev. B 78, 180407(R) (2008) | 10.1103/PhysRevB.78.180407 | null | cond-mat.str-el cond-mat.mtrl-sci | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We report an unusual nearly ferromagnetic, heavy-mass state with a
surprisingly large Wilson ratio $R_{\textrm{w}}$ (e.g., $R_{\textrm{w}}\sim$
700 for $x =$ 0.2) in double layered ruthenates
(Sr$_{1-x}$Ca$_{x}$)$_{3}$Ru$_{2}$O$_{7}$ with 0.08 $< x <$ 0.4. This state
does not evolve into a long-range ferromagnetically ordered state despite
considerably strong ferromagnetic correlations, but freezes into a
cluster-spin-glass at low temperatures. In addition, evidence of non-Fermi
liquid behavior is observed as the spin freezing temperature of the
cluster-spin-glass approaches zero near $x \approx$ 0.1. We discuss the origin
of this unique magnetic state from the Fermi surface information probed by Hall
effect measurements.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 19:45:10 GMT"
},
{
"version": "v2",
"created": "Thu, 9 Aug 2007 20:50:53 GMT"
},
{
"version": "v3",
"created": "Mon, 13 Aug 2007 15:47:47 GMT"
},
{
"version": "v4",
"created": "Tue, 14 Aug 2007 18:31:01 GMT"
},
{
"version": "v5",
"created": "Mon, 27 Oct 2008 14:56:29 GMT"
}
] | 2012-07-16T00:00:00 | [
[
"Qu",
"Zhe",
""
],
[
"Spinu",
"Leonard",
""
],
[
"Yuan",
"Huiqiu",
""
],
[
"Dobrosavljevic",
"Vladimir",
""
],
[
"Bao",
"Wei",
""
],
[
"Lynn",
"Jeffrey W.",
""
],
[
"Nicklas",
"M.",
""
],
[
"Peng",
"Jin",
""
],
[
"Liu",
"Tijiang",
""
],
[
"Fobes",
"David",
""
],
[
"Flesch",
"Etienne",
""
],
[
"Mao",
"Z. Q.",
""
]
] |
0708.1292 | Shu Huang | S. Huang, C. Chandre and T. Uzer | Periodic orbit bifurcations as an ionization mechanism: The
bichromatically driven hydrogen atom | null | J. Phys. B: At. Mol. Opt. Phys. 41 (2008) 035604 | 10.1088/0953-4075/41/3/035604 | null | nlin.CD | null | We investigate the multiphoton ionization of hydrogen driven by a strong
bichromatic microwave field. In a regime where classical and quantum
simulations agree, periodic orbit analysis captures the mechanism: Through the
linear stability of periodic orbits we match qualitatively the variation of
experimental ionization rates with control parameters such as the amplitudes of
the two modes of the field or their relative phases. Moreover, we discuss an
empirical formula which reproduces quantum simulations to a high degree of
accuracy. This quantitative agreement shows the mechanism by which short
periodic orbits organize the dynamics in multiphoton ionization. We also
analyze the effect of longer pulse durations. Finally we compare our results
with those based on the peak amplitude rule. Both qualitative and quantitative
analyses are implemented for different mode locked fields. In parameter space,
the localization of the period doubling and halving allows one to predict the
set of parameters (amplitudes and phase lag) where ionization occurs.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 19:48:45 GMT"
},
{
"version": "v2",
"created": "Mon, 17 Dec 2007 22:45:04 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Huang",
"S.",
""
],
[
"Chandre",
"C.",
""
],
[
"Uzer",
"T.",
""
]
] |
0708.1293 | Owe Philipsen | Owe Philipsen (Munster U.) | Lattice QCD at finite temperature and density | 32 pages, typos corrected, reference added. Lectures given at 45.
Internationale Universitatswochen fur Theoretische Physik: (Schladming Winter
School on Theoretical Physics): Conceptual and Numerical Challenges in
Femto-Scale and Peta-Scale Physics, Schladming, Styria, Austria, 24 Feb - 3
Mar 2007 | Eur.Phys.J.ST 152:29-60,2007 | 10.1140/epjst/e2007-00376-3 | MS-TP-07-22 | hep-lat hep-ph nucl-th | null | QCD at finite temperature and density is becoming increasingly important for
various experimental programmes, ranging from heavy ion physics to
astro-particle physics. The non-perturbative nature of non-abelian quantum
field theories at finite temperature leaves lattice QCD as the only tool by
which we may hope to come to reliable predictions from first principles. This
requires careful extrapolations to the thermodynamic, chiral and continuum
limits in order to eliminate systematic effects introduced by the
discretization procedure. After an introduction to lattice QCD at finite
temperature and density, its possibilities and current systematic limitations,
a review of present numerical results is given. In particular, plasma
properties such as the equation of state, screening masses, static quark free
energies and spectral functions are discussed, as well as the critical
temperature and the QCD phase structure at zero and finite density.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 14:32:54 GMT"
},
{
"version": "v2",
"created": "Fri, 16 Nov 2007 10:16:42 GMT"
}
] | 2009-11-02T00:00:00 | [
[
"Philipsen",
"Owe",
"",
"Munster U."
]
] |
0708.1294 | Francoise Heres-Renzetti | R. Rao, J.-E. Bradby, J.-S. Williams | Nanoindentation-Induced Phase Transformation in Silicon | null | Dans European Nano Systems Worshop - ENS 2006, Paris : France
(2006) | null | null | cond-mat.mtrl-sci | null | Nanoindentation-induced phase transformation in silicon has been studied. A
series of nanoindentations were made with the sharp diamond Berkovich tip.
During nanoindentations, maximum load ranged from 2000 $\mu$N to 5000 $\mu$N,
with a 1000 $\mu$N/sec loading rate. Slow unloading rate at 100$\mu$N/sec was
chosen to favor the formation of the crystalline end phases, high pressure
phase (Si-III and Si-XII). Fast unloading rate at 1000$\mu$N/sec was used to
obtain amorphous phase. The phase transformation was examined by Raman
spectroscopy and plan-view transmission electron microscopy (TEM). HPP have
been identified even if no "pop-in" and "pop-out" observed in load-depth
characteristics curves. HPP appeared in c-Si when the maximum load up to 3000
$\mu$N. TEM images have been revealed that the optimization HPP transformation
in c-Si at the nanoscale occurred when the maximum load applied at 5000 $\mu$N.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 14:22:56 GMT"
}
] | 2007-08-10T00:00:00 | [
[
"Rao",
"R.",
""
],
[
"Bradby",
"J. -E.",
""
],
[
"Williams",
"J. -S.",
""
]
] |
0708.1295 | Michael Creutz | Michael Creutz | Why rooting fails | 10 pages, 5 figures. Invited talk at the XXV International Symposium
on Lattice Field Theory, July 30 - August 4 2007, Regensburg, Germany | PoSLAT2007:007,2007 | null | null | hep-lat | null | I explore the origins of the unphysical predictions from rooted staggered
fermion algorithms. Before rooting, the exact chiral symmetry of staggered
fermions is a flavored symmetry among the four "tastes." The rooting procedure
averages over tastes of different chiralities. This averaging forbids the
appearance of the correct 't Hooft vertex for the target theory.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 14:23:34 GMT"
},
{
"version": "v2",
"created": "Fri, 16 Nov 2007 14:19:47 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Creutz",
"Michael",
""
]
] |
0708.1296 | Hua Qin | Dominik V. Scheible, Hua Qin, Hyun-Seok Kim, and Robert H. Blick | Doped Nano-Electromechanical Systems | 4 pages, 4 figures | null | 10.1002/pssr.200701186 | null | cond-mat.mes-hall cond-mat.mtrl-sci | null | We present a new generation of nano-electromechanical systems (NEMS), which
are realized by doping the semiconductor base material. In contrast to the
traditional approach these doped NEMS (D-NEMS) do not require a metallization
layer. This makes them far lighter and hence increases resonance frequency and
quality factor. Additionally, D-NEMS can be tuned from the conductive state
into an insulating one. This will enable a host of new device designs, like
mechanically tunable pin-junctions and nanomechanical single electron switches.
We demonstrate D-NEMS fabrication and operation from the intrinsic, to the
light, and to the heavy regime of doping.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 16:02:51 GMT"
}
] | 2015-05-13T00:00:00 | [
[
"Scheible",
"Dominik V.",
""
],
[
"Qin",
"Hua",
""
],
[
"Kim",
"Hyun-Seok",
""
],
[
"Blick",
"Robert H.",
""
]
] |
0708.1297 | Gonzalo Abal | G. Abal, R. Donangelo, F. Severo, R. Siri | Decoherent quantum walks driven by a generic coin operation | null | Physica A, Vol 387/1 pp 335-345 (2007) | 10.1016/j.physa.2007.08.058 | null | quant-ph | null | We consider the effect of different unitary noise mechanisms on the evolution
of a quantum walk (QW) on a linear chain with a generic coin operation: (i)
bit-flip channel noise, restricted to the coin subspace of the QW, and (ii)
topological noise caused by randomly broken links in the linear chain.
Similarities and differences in the respective decoherent dynamics of the
walker as a function of the probability per unit time of a decoherent event
taking place are discussed.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 16:04:53 GMT"
}
] | 2007-11-27T00:00:00 | [
[
"Abal",
"G.",
""
],
[
"Donangelo",
"R.",
""
],
[
"Severo",
"F.",
""
],
[
"Siri",
"R.",
""
]
] |
0708.1298 | Francoise Heres-Renzetti | J.-H. Ting, C.-C. Chiu, F.-Y. Huang | Carbon nanotube array vias for interconnect applications | null | Dans European Nano Systems Worshop - ENS 2006, Paris : France
(2006) | null | null | cond-mat.mtrl-sci | null | The material and electrical properties of the CNT single vias and array vias
grown by microwave plasma-enhanced chemical vapor deposition were investigated.
The diameters of multiwall carbon nanotubes (MWNTs) grown on the bottom
electrode of Ta decrease with increasing pretreatment power and substrate
temperature while the effects of the growth power and methane flow ratio are
insignificant The decrease of CNT diameters leads to the decrease of the CNT
via diode devices. The increase of growth power enhances the CNT graphitization
degree and thue the conductivity of CNT via diode devices. In the same via
region, the MWNT diode resistances of the array vias are lower than those of
the single vias. The MWNT diode resistances on the bottom electrode of titanium
are lower than those on the bottom electrode of tantalum. It may be attributed
to the smaller tube diameters on the bottom electrode of Ti and the work
function difference between Ta and Ti films with respect to the work function
of CNTs.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 14:26:13 GMT"
}
] | 2007-08-10T00:00:00 | [
[
"Ting",
"J. -H.",
""
],
[
"Chiu",
"C. -C.",
""
],
[
"Huang",
"F. -Y.",
""
]
] |
0708.1299 | Brooke Shipley | Brooke Shipley | Correction to: HZ-algebra spectra are differential graded algebras | The original article is actually correct as stated. Thus, this
correction article is unnecessary. | null | null | null | math.AT | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This correction article is actually unnecessary.
The proof of Theorem 1.2, concerning commutative HQ-algebra spectra and
commutative differential graded algebras, in the author's paper [American
Journal of Mathematics vol. 129 (2007) 351-379 (arxiv:math/0209215v4)] is
correct as originally stated. Neil Strickland carefully proved that D is
symmetric monoidal; so Proposition 4.7 and hence also Theorem 1.2 hold as
stated. Strickland's proof will appear in joint work with Stefan Schwede; see
related work in Strickland's [arxiv:0810.1747]. Note here D is defined as a
colimit of chain complexes; in contrast, non-symmetric monoidal functors
analogous to D are defined as homotopy colimits of spaces in previous work of
the author.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 16:17:32 GMT"
},
{
"version": "v2",
"created": "Tue, 30 Jun 2009 16:35:26 GMT"
}
] | 2009-06-30T00:00:00 | [
[
"Shipley",
"Brooke",
""
]
] |
0708.1300 | Stefan Schumacher | S. Schumacher, N. H. Kwong, R. Binder | Polariton amplification in a multiple-quantum-well resonant photonic
crystal | null | null | null | null | cond-mat.other | null | Based on a microscopic many-particle theory we study the amplification of
polaritons in a multiple-quantum-well resonant photonic crystal. For the
Bragg-spaced multiple quantum wells under investigation we predict that in a
typical pump-probe setup four-wave mixing processes can lead to an unstable
energy transfer from the pump into the probe and the background-free four-wave
mixing directions. We find that under certain excitation conditions this
phase-conjugate oscillation induced instability can lead to a large
amplification of the weak probe pulse.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 16:31:36 GMT"
}
] | 2007-08-10T00:00:00 | [
[
"Schumacher",
"S.",
""
],
[
"Kwong",
"N. H.",
""
],
[
"Binder",
"R.",
""
]
] |
0708.1301 | Rachid Benbrik | Abdesslam Arhrib (NCU & Tanger U), Rachid Benbrik (CYCU & Cadi Ayyad
U), Mohamed Chabab (Cadi Ayyad U), Wei Ting Chang, Tzu-Chiang Yuan (NTHU) | CP violation in Charged Higgs Bosons decays $H^\pm \to W^\pm (\gamma,
Z)$ in the Minimal Supersymmetric Standard Model (MSSM) | Invited talk at CTP Symposium on Supersymmetry at LHC: Theoretical
and Experimental Prospectives, Cario, Egypt, 11-14 Mar 2007 | Int.J.Mod.Phys.A22:6022-6032,2007 | 10.1142/S0217751X07039201 | null | hep-ph | null | One loop mediated charged Higgs bosons decays $H^\pm\to W^\pm V$, $V= Z,
\gamma$ are studied in the Minimal Supersymmetric Standard Model (MSSM) with
and without CP violating phases. We evaluate the MSSM contributions to these
processes taking into account $B\to X_s\gamma$ constraint as well as
experimental constraints on the MSSM parameters. In the MSSM, we found that in
the intermediate range of $\tan\beta \la 10$ and for large
A_t and large $\mu$, where the lightest top squark becomes very light and
hence non-decoupled, the branching ratio of $H^\pm \to W^{\pm} Z$ can be of the
order 10^{-3} while the branching ratio of $H^\pm \to W^{\pm} \gamma$ is of the
order 10^{-5}. We found also that the CP violating phases of soft SUSY
parameters can modify the branching ratio by about one order of magnitude. We
also show that MSSM with CP violating phases lead to CP-violating asymmetry in
the decays $H^+ \to W^+V$ and $H^- \to W^-V$. Such CP asymmetry can be rather
large and can reach 80% in some region of parameter space.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 16:34:11 GMT"
}
] | 2010-11-03T00:00:00 | [
[
"Arhrib",
"Abdesslam",
"",
"NCU & Tanger U"
],
[
"Benbrik",
"Rachid",
"",
"CYCU & Cadi Ayyad\n U"
],
[
"Chabab",
"Mohamed",
"",
"Cadi Ayyad U"
],
[
"Chang",
"Wei Ting",
"",
"NTHU"
],
[
"Yuan",
"Tzu-Chiang",
"",
"NTHU"
]
] |
0708.1302 | Marco Bernasconi | S. Caravati, M. Bernasconi, T. D. Kuehne, M. Krack, and M. Parrinello | Coexistence of tetrahedral and octahedral-like sites in amorphous phase
change materials | 6 pages, 10 figures including supplementary material | Applied Physics Letters 91, 171906 (2007) | 10.1063/1.2801626 | null | cond-mat.mtrl-sci cond-mat.dis-nn | null | Chalcogenide alloys are materials of interest for optical recording and
non-volatile memories. We perform ab-initio molecular dynamics simulations
aiming at shading light onto the structure of amorphous Ge2Sb2Te5 (GST), the
prototypical material in this class. First principles simulations show that
amorphous GST obtained by quenching from the liquid phase displays two types of
short range order. One third of Ge atoms are in a tetrahedral environment while
the remaining Ge, Sb and Te atoms display a defective octahedral environment,
reminiscent of cubic crystalline GST.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 16:36:02 GMT"
},
{
"version": "v2",
"created": "Tue, 1 Apr 2008 11:27:27 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Caravati",
"S.",
""
],
[
"Bernasconi",
"M.",
""
],
[
"Kuehne",
"T. D.",
""
],
[
"Krack",
"M.",
""
],
[
"Parrinello",
"M.",
""
]
] |
0708.1303 | Owen R. Long | The BABAR Collaboration: B. Aubert et al | Search for the decay B+ -> K+ tau-/+ mu+/- | 7 pages, 2 figures, version published in Physical Review Letters | Phys.Rev.Lett.99:201801,2007 | 10.1103/PhysRevLett.99.201801 | BABAR-PUB-07/040, SLAC-PUB-12709 | hep-ex | null | We present a search for the lepton flavor violating decay B+ --> K+ tau-/+
mu+/- using 383 million B Bbar events collected by the BABAR experiment. The
branching fraction for this decay can be substantially enhanced in new physics
models. The kinematics of the tau from the signal B decay are inferred from the
K+, mu, and other B in the event, which is fully reconstructed in one of a
variety of hadronic decay modes, allowing the signal B candidate to be fully
reconstructed. We observe no excess of events over the expected background and
set a limit of B(B+ --> K+ tau mu) < 7.7 x 10^-5 at 90% confidence level, where
the branching fraction is for the sum of the K+ tau- mu+ and K+ tau+ mu- final
states. We use this result to improve a model-independent bound on the energy
scale of flavor-changing new physics.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 16:01:00 GMT"
},
{
"version": "v2",
"created": "Tue, 11 Dec 2007 20:38:28 GMT"
}
] | 2010-04-12T00:00:00 | [
[
"The BABAR Collaboration",
"",
""
],
[
"al",
"B. Aubert et",
""
]
] |
0708.1304 | Harold U. Baranger | A. D. Guclu, A. Ghosal, C. J. Umrigar, and H. U. Baranger | Interaction-Induced Strong Localization in Quantum Dots | 4 pages, published version, revised discussion | Phys. Rev. B 77, 041301(R) (2008) | 10.1103/PhysRevB.77.041301 | null | cond-mat.mes-hall cond-mat.str-el | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We argue that Coulomb blockade phenomena are a useful probe of the cross-over
to strong correlation in quantum dots. Through calculations at low density
using variational and diffusion quantum Monte Carlo (up to r_s ~ 55), we find
that the addition energy shows a clear progression from features associated
with shell structure to those caused by commensurability of a Wigner crystal.
This cross-over (which occurs near r_s ~ 20 for spin-polarized electrons) is,
then, a signature of interaction-driven localization. As the addition energy is
directly measurable in Coulomb blockade conductance experiments, this provides
a direct probe of localization in the low density electron gas.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 14:32:58 GMT"
},
{
"version": "v2",
"created": "Mon, 10 Aug 2009 21:50:06 GMT"
}
] | 2009-08-11T00:00:00 | [
[
"Guclu",
"A. D.",
""
],
[
"Ghosal",
"A.",
""
],
[
"Umrigar",
"C. J.",
""
],
[
"Baranger",
"H. U.",
""
]
] |
0708.1305 | Kirpal Nandra | K. Nandra (Imperial College London), P.M. O'Neill (Imperial College
London), I.M. George (UMBC), J.N. Reeves (NASA/GSFC) | An XMM-Newton survey of broad iron lines in Seyfert galaxies | 36 pages, 13 figures, accepted for publication in MNRAS | null | 10.1111/j.1365-2966.2007.12331.x | null | astro-ph | null | We present an analysis of the X-ray spectra of a sample of 37 observations of
26 Seyfert galaxies observed by XMM-Newton in order to characterize their iron
K emission. All objects show evidence for iron line emission in the 6-7 keV
band. A narrow core at 6.4 keV is seen almost universally in the spectra, and
we model this using a neutral Compton reflection component, assumed to be
associated with distant, optically thick material such as the molecular torus.
Once this, and absorption by a zone of ionized gas in the line-of-sight is
accounted for, less than half of the sample observations show an acceptable
fit. Approximately 2/3 of the sample shows evidence for further, broadened
emission in the iron K-band. When modeled with a Gaussian, the inferred energy
is close to that expected for neutral iron, with a slight redshift, with an
average velocity width of ~0.1c. The mean parameters are consistent with
previous ASCA results and support the idea that the broad components can be
associated with the accretion disk. Before proceeding to that conclusion, we
test an alternative model comprising a blend of 3-4 narrow, unshifted emission
lines (including the 6.4 keV core), together with 1-2 zones of highly ionized
gas in the line-of-sight. Around 1/3 of the objects are not adequately fit by
this model, and in general better fits are obtained with a relativistic disk
line model, which has fewer free parameters. Nonetheless we find that
absorption by ionized gas affects the spectrum above 2.5 keV in approximately
half the sample. There is evidence for multiple ionized zones in at least 3
objects, but in all those cases a blurred reflector is required in addition to
the complex absorption. (truncated)
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 14:38:48 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Nandra",
"K.",
"",
"Imperial College London"
],
[
"O'Neill",
"P. M.",
"",
"Imperial College\n London"
],
[
"George",
"I. M.",
"",
"UMBC"
],
[
"Reeves",
"J. N.",
"",
"NASA/GSFC"
]
] |
0708.1306 | Alan R. White | Alan R. White | The LHC Pomeron and Unification of the Standard Model - a Bound-State
S-Matrix Within a Fixed-Point Field Theory ? | Presented at the Small-x and Diffraction Workshop, Fermilab,March
2007 | null | null | null | hep-ph | null | The Critical Pomeron solution of high-energy unitarity leads to a unique
underlying massless field theory that might be the origin of the Standard
Model. A color sextet quark sector - producing both electroweak symmetry
breaking and dark matter - is added to QCD to saturate asymptotic freedom. The
sextet sector is then embedded uniquely in ``QUD'' - an anomaly free, just
asymptotically free, massless SU(5) theory with elementary lepton and triplet
quark sectors very close to the Standard Model. A multi-regge bound-state
S-Matrix is constructed using infra-red divergent scaling reggeon interactions
that couple via massless fermion chiral anomalies. Within the QCD sub-sector
there is an ``anomalous wee gluon'' critical phenomenon that produces a
spectrum with confinement and chiral symmetry breaking. The exponentiation of
left-handed gauge boson divergences implies that the full set of composite
interactions and the low-mass spectrum of QUD could be just those of the
Standard Model. All particles, including neutrinos, appear as massive,
Goldstone boson related, bound-states and there is no Higgs field. The
different coupling strengths, multiple mass scales, and multigenerational
structure should also appear. The Critical Pomeron may be the S-Matrix
manifestation of the underlying fixed-point field theory.
If QUD underlies the Standard Model as described, the sextet sector should
produce new, unmistakeable, large cross-sections at the LHC, for which the
pomeron could be the main diagnostic!
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 14:49:39 GMT"
}
] | 2007-08-10T00:00:00 | [
[
"White",
"Alan R.",
""
]
] |
0708.1307 | Horacio Failache | Horacio Failache, Lorenzo Lenci, Arturo Lezama, Daniel Bloch, Martial
Ducloy | Theoretical study of dark resonances in micro-metric thin cells | 12 pages, 11 figures theoretical article | null | 10.1103/PhysRevA.76.053826 | null | quant-ph physics.atom-ph | null | We investigate theoretically dark resonance spectroscopy for a dilute atomic
vapor confined in a thin (micro-metric) cell. We identify the physical
parameters characterizing the spectra and study their influence. We focus on a
Hanle-type situation, with an optical irradiation under normal incidence and
resonant with the atomic transition. The dark resonance spectrum is predicted
to combine broad wings with a sharp maximum at line-center, that can be singled
out when detecting a derivative of the dark resonance spectrum. This narrow
signal derivative, shown to broaden only sub-linearly with the cell length, is
a signature of the contribution of atoms slow enough to fly between the cell
windows in a time as long as the characteristic ground state optical pumping
time. We suggest that this dark resonance spectroscopy in micro-metric thin
cells could be a suitable tool for probing the effective velocity distribution
in the thin cell arising from the atomic desorption processes, and notably to
identify the limiting factors affecting desorption under a grazing incidence.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 14:59:53 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Failache",
"Horacio",
""
],
[
"Lenci",
"Lorenzo",
""
],
[
"Lezama",
"Arturo",
""
],
[
"Bloch",
"Daniel",
""
],
[
"Ducloy",
"Martial",
""
]
] |
0708.1308 | Goren Gordon | Goren Gordon and Gershon Kurizki | Universal Dephasing Control During Quantum Computation | 4 pages,3 figures | null | 10.1103/PhysRevA.76.042310 | null | quant-ph | null | Dephasing is a ubiquitous phenomenon that leads to the loss of coherence in
quantum systems and the corruption of quantum information. We present a
universal dynamical control approach to combat dephasing during all stages of
quantum computation, namely, storage, single- and two-qubit operators. We show
that (a) tailoring multi-frequency gate pulses to the dephasing dynamics can
increase fidelity; (b) cross-dephasing, introduced by entanglement, can be
eliminated by appropriate control fields; (c) counter-intuitively and contrary
to previous schemes, one can increase the gate duration, while simultaneously
increasing the total gate fidelity.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 15:07:58 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Gordon",
"Goren",
""
],
[
"Kurizki",
"Gershon",
""
]
] |
0708.1309 | Anak Agung Julius | A.A. Julius, J.W. Polderman, and A.J. van der Schaft | Parametrization of the regular equivalences of the canonical controller
and its applications | submitted to IEEE Trans. Automatic Control. The title has been
changed from the previous arXiv version to avoid confusion with the submitted
version | null | null | null | math.OC | null | We study control problems for linear systems in the behavioral framework. Our
focus is a class of regular controllers that are equivalent to the canonical
controller. The canonical controller is a particular controller that is
guaranteed to be a solution whenever a solution exists. However, it has been
shown that in most cases, the canonical controller is not regular. The main
result of the paper is a parametrization of all regular controllers that are
equivalent to the canonical controller. The parametrization is then used to
solve two control problems. The first problem is related to designing a regular
controller that uses as few control channels as possible. The second problem is
to design a regular controller that satisfies a predefined input-output
partitioning constraint. In both problems, based on the parametrization, we
present algorithms that does the controller design.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 15:21:42 GMT"
},
{
"version": "v2",
"created": "Mon, 24 Sep 2007 12:21:59 GMT"
}
] | 2007-09-24T00:00:00 | [
[
"Julius",
"A. A.",
""
],
[
"Polderman",
"J. W.",
""
],
[
"van der Schaft",
"A. J.",
""
]
] |
0708.1310 | Seckin Kurkcuoglu | Seckin Kurkcuoglu, Olaf Lechtenfeld | Quantum Aspects of the Noncommutative Sine-Gordon Model | 1+14 pages, 8 eps figures, Added references, Version to appear in
JHEP | JHEP 0709:020,2007 | 10.1088/1126-6708/2007/09/020 | ITP-UH-18/07 | hep-th | null | In this paper, we first use semi-classical methods to study quantum field
theoretical aspects of the integrable noncommutative sine-Gordon model proposed
in [hep-th/0406065]. In particular, we examine the fluctuations at quadratic
order around the static kink solution using the background field method. We
derive equations of motion for the fluctuations and argue that at O(theta^2)
the spectrum of fluctuations remains essentially the same as that of the
corresponding commutative theory. We compute the one-loop two-point functions
of the sine-Gordon field and the additional scalar field present in the model
and exhibit logarithmic divergences, only some of which lead to UV/IR mixing.
We briefly discuss the one-loop renormalization in Euclidean signature and
comment on the obstacles in determining the noncommutativity corrections to the
quantum mass of the kink.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 15:22:25 GMT"
},
{
"version": "v2",
"created": "Fri, 31 Aug 2007 12:51:37 GMT"
}
] | 2009-06-11T00:00:00 | [
[
"Kurkcuoglu",
"Seckin",
""
],
[
"Lechtenfeld",
"Olaf",
""
]
] |
0708.1311 | Collaboration Secretariat Opal | The OPAL collaboration, et al | Measurement of the e+e- -> W+W- cross section and W decay branching
fractions at LEP | 23 pages, 5 figures, Submitted to Eur Phys J.C | Eur.Phys.J.C52:767-785,2007 | 10.1140/epjc/s10052-007-0442-0 | CERN-PH-EP/2007-027 | hep-ex | null | From a total data sample of 701.1 pb^-1 recorded with e+e- centre-of-mass
energies of sqrt = 161-209 GeV with the OPAL detector at LEP, 11693 W-pair
candidate events are selected. These data are used to obtain measurements of
the W-pair production cross sections at 10 different centre-of-mass energies.
The ratio of the measured cross sections to the Standard Model expectation is
found to be: data/SM = 1.002 +- 0.011(stat.) +- 0.007(syst.) +- 0.005(theory),
where the uncertainties are statistical, experimental systematics and theory
systematics respectively. The data are used to determine the W boson branching
fractions, which are found to be consistent with lepton universality of the
charged current interaction. Assuming lepton universality, the branching ratio
to hadrons is determined to be 67.41 +- 0.37(stat.) +- 0.23(syst.)%, from which
the CKM matrix element Vcs is determined to be
0.96+-0.017(stat.)+-0.012(syst.).
The differential cross section as a function of the W^- production angle is
measured for the qqev and qqmv final states. The results described in this
paper are consistent with the expectations from the Standard Model.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 15:31:19 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"The OPAL collaboration",
"",
""
]
] |
0708.1312 | Aneta Siemiginowska | Aneta Siemiginowska (1), D.E.Harris (1), Thomas L. Aldcroft (1),
Lukasz Stawarz (2), C.C.Cheung (2,3), Marek Sikora (4), Jill Bechtold (5)
((1) Harvard-Smithonian Center for Astrophysics, Cambridge, MA (2) Kavli
Institute for Particle Astrophysics and Cosmology, Stanford University, CA,
(3) Jansky Postdoctoral Fellow; National Radio Astronomy Observatory (4)
Copernicus Astronomical Center, Warsaw, Poland (5) Steward Observatory,
University of Arizona, Tucson, AZ) | The Case of the 300 kpc Long X-ray Jet in PKS 1127-145 at z=1.18 | 5 pages, 5 figures. To be published in the proceedings of
"Extragalactic Jets: Theory and Observation from Radio to Gamma Ray" ASP
Conference Series, T. A. Rector and D. S. De Young (eds.) | null | null | null | astro-ph | null | The complex X-ray morphology of the 300 kpc long X-ray jet in PKS1127-145
(z=1.18 quasar) is clearly discerned in a ~100 ksec Chandra observation. The
jet X-ray surface brightness gradually decreases by an order of magnitude going
out from the core. The X-ray spectrum of the inner jet is relatively flat with
alpha_X=0.66+/-0.15 and steep in the outer jet with alpha_X=1.0+/-0.2. The
X-ray and radio jet intensity profiles are strikingly different, with the radio
emission peaking strongly at the two outer knots while the X-ray emission is
strongest in the inner jet region. We discuss the constraints implied by these
data on the X-ray emission models and conclude that ``one-zone'' models fail
and that at least a two-component model is needed to explain the jet's
broadband emission. We propose that the X-ray emission originates in the jet
proper while the bulk of the radio emission comes from a surrounding jet
sheath. We also consider intermittent jet activity as a possible cause of the
observed jet morphology.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 15:38:45 GMT"
}
] | 2007-08-10T00:00:00 | [
[
"Siemiginowska",
"Aneta",
""
],
[
"Harris",
"D. E.",
""
],
[
"Aldcroft",
"Thomas L.",
""
],
[
"Stawarz",
"Lukasz",
""
],
[
"Cheung",
"C. C.",
""
],
[
"Sikora",
"Marek",
""
],
[
"Bechtold",
"Jill",
""
]
] |
0708.1313 | Peter Jung | Peter Jung and Achim Rosch | Spin conductivity in almost integrable spin chains | 6 pages, 5 figures | null | 10.1103/PhysRevB.76.245108 | null | cond-mat.str-el | null | The spin conductivity in the integrable spin-1/2 XXZ-chain is known to be
infinite at finite temperatures T for anisotropies -1 < Delta < 1.
Perturbations which break integrability, e.g. a next-nearest neighbor coupling
J', render the conductivity finite. We construct numerically a non-local
conserved operator J_parallel which is responsible for the finite spin Drude
weight of the integrable model and calculate its decay rate for small J'. This
allows us to obtain a lower bound for the spin conductivity sigma_s >= c(T) /
J'^2, where c(T) is finite for J' to 0. We discuss the implication of our
result for the general question how non-local conservation laws affect
transport properties.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 15:51:17 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Jung",
"Peter",
""
],
[
"Rosch",
"Achim",
""
]
] |
0708.1314 | Sang-Hyun Oh | Nathan C. Lindquist, Antoine Lesuffleur and Sang-Hyun Oh | Periodic Modulation of Extraordinary Optical Transmission through
Subwavelength Hole Arrays using Surrounding Bragg Mirrors | 9 pages, 5 figures | Phys. Rev. B 76, 155109 (2007) | 10.1103/PhysRevB.76.155109 | null | physics.optics | null | The enhanced light transmission through an array of subwavelength holes
surrounded by Bragg mirrors is studied, showing that the mirrors act to confine
the surface plasmons associated with the Extraordinary Optical Transmission
effect, forming a surface resonant cavity. The overall effect is increased
light transmission intensity by more than a factor of three beyond the already
enhanced transmission, independent of whether the Bragg mirrors are on the
input or the output side of the incident light. The geometry of the Bragg
mirror structures controls the enhancement, and can even reduce the
transmission in half. By varying these geometric parameters, we were able to
periodically modulate the transmission of light for specific wavelengths,
consistent with the propagation and interference of surface plasmon waves in a
resonant cavity. FDTD simulations and a wave propagation model verify this
effect.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 15:47:29 GMT"
}
] | 2007-10-11T00:00:00 | [
[
"Lindquist",
"Nathan C.",
""
],
[
"Lesuffleur",
"Antoine",
""
],
[
"Oh",
"Sang-Hyun",
""
]
] |
0708.1315 | Fabio Mezzacapo | Fabio Mezzacapo and Massimo Boninsegni | Superfluidity of isotopically doped parahydrogen clusters | 4 pages, 5 figures | Phys. Rev. A 76, 021201 (2007) | 10.1103/PhysRevA.76.021201 | null | cond-mat.stat-mech | null | It is shown by computer simulations that superfluid {\it para}-hydrogen
clusters of more than 22 molecules can be turned insulating and "solidlike" by
the replacement of as few as one or two molecules, with ones of the heavier
{\it ortho}-deuterium isotope. A much smaller effect is observed with
substitutional {\it ortho}-hydrogen. Substitutional {\it ortho}-deuterium
molecules prevalently sit in the inner part of the cluster, whereas {\it
ortho}-hydrogen impurities reside primarily in the outer shell, near the
surface. Implications on the superfluidity of pure {\it para}-hydrogen clusters
are discussed.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 15:49:10 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Mezzacapo",
"Fabio",
""
],
[
"Boninsegni",
"Massimo",
""
]
] |
0708.1316 | Diego Altamirano | D. Altamirano, P. Casella, A. Patruno, R. Wijnands, M. van der Klis | Intermittent millisecond X-ray pulsations from the neutron-star X-ray
transient SAX J1748.9-2021 in the globular cluster NGC 6440 | 5 pages, 4 figures, Accepted by ApJL - Uses emulateapj.cls - New
figure added: "Pulse frequency as a function of orbital phase". Figure 4 has
changed. Text has been rewritten as to fit the 4 pages limit | null | 10.1086/528983 | null | astro-ph | null | We report on intermittent X-ray pulsations with a frequency of 442.36 Hz from
the neutron-star X-ray binary SAX J1748.9--2021 in the globular cluster NGC
6440. The pulsations were seen during both 2001 and 2005 outbursts of the
source, but only intermittently, appearing and disappearing on timescales of
hundreds of seconds. We find a suggestive relation between the occurrence of
type-I X-ray bursts and the appearance of the pulsations but the relation is
not strict. This behavior is very similar to that of the intermittent accreting
millisecond X-ray pulsar HETE J1900.1--2455. The reason for the intermittence
of the pulsations remains unclear. However it is now evident that a strict
division between pulsating and non-pulsating does not exist. By studying the
Doppler shift of the pulsation frequency we determine an orbit with a period of
8.7 hrs and an projected semi major axis of 0.39 lightsec. The companion star
might be a main--sequence or a slightly evolved star with a mass of $\sim$1
$M_\odot$. Therefore, SAX J1748.9--2021 has a longer period and may have a more
massive companion star than all the other accreting millisecond X-ray pulsars
except for Aql X-1.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 15:49:24 GMT"
},
{
"version": "v2",
"created": "Mon, 7 Jan 2008 17:25:47 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Altamirano",
"D.",
""
],
[
"Casella",
"P.",
""
],
[
"Patruno",
"A.",
""
],
[
"Wijnands",
"R.",
""
],
[
"van der Klis",
"M.",
""
]
] |
0708.1317 | F. Saueressig | Martin Reuter and Frank Saueressig | Functional Renormalization Group Equations, Asymptotic Safety, and
Quantum Einstein Gravity | Based on lectures given by M.R. at the ``First Quantum Geometry and
Quantum Gravity School'', Zakopane, Poland, March 2007, and the ``Summer
School on Geometric and Topological Methods for Quantum Field Theory'', Villa
de Leyva, Colombia, July 2007, and by F.S. at NIKHEF, Amsterdam, The
Netherlands, June 2006 | null | null | null | hep-th | null | These lecture notes provide a pedagogical introduction to a specific
continuum implementation of the Wilsonian renormalization group, the effective
average action. Its general properties and, in particular, its functional
renormalization group equation are explained in a simple scalar setting. The
approach is then applied to Quantum Einstein Gravity (QEG). The possibility of
constructing a fundamental theory of quantum gravity in the framework of
Asymptotic Safety is discussed and the supporting evidence is summarized.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 16:09:49 GMT"
}
] | 2007-08-10T00:00:00 | [
[
"Reuter",
"Martin",
""
],
[
"Saueressig",
"Frank",
""
]
] |
0708.1318 | Deepak Mathur | A. K. Dharmadhikari, K. Alti, J. A. Dharmadhikari, and D. Mathur | Control of the Onset of Filamentation in Condensed Media | To appear in Phys. Rev. A | null | 10.1103/PhysRevA.76.033811 | null | physics.optics physics.plasm-ph | null | Propagation of intense, ultrashort laser pulses through condensed media like
crystals of BaF$_2$ and sapphire results in the formation of filaments. We
demonstrate that the onset of filamentation may be controlled by rotating the
plane of polarization of incident light. We directly visualize filamentation in
BaF_2 via six-photon absorption-induced fluorescence and, concomitantly, by
probing the spectral and spatial properties of white light that is generated.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 15:35:23 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Dharmadhikari",
"A. K.",
""
],
[
"Alti",
"K.",
""
],
[
"Dharmadhikari",
"J. A.",
""
],
[
"Mathur",
"D.",
""
]
] |
0708.1319 | Francesco Hautmann | F. Hautmann | Coordinate-space picture and $x \to 1$ singularities at fixed $k_\perp$ | Based on talks given at the "HERA and the LHC" Workshop (Hamburg,
March 2007) and at the "DIS07" Workshop (Munich, April 2007) | null | null | null | hep-ph | null | We discuss ongoing progress towards precise characterizations of parton
distributions at fixed transverse momentum, focusing on matrix elements in
coordinate space and the treatment of endpoint singularities.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 15:57:29 GMT"
}
] | 2007-08-10T00:00:00 | [
[
"Hautmann",
"F.",
""
]
] |
0708.1320 | Anatoly Kolomeisky | Stanislav Kotsev and Anatoly B. Kolomeisky | Translocation of polymers with folded configurations across nanopores | submitted to J. Chem. Phys | null | 10.1063/1.2800008 | null | cond-mat.stat-mech cond-mat.soft | null | The transport of polymers with folded configurations across membrane pores is
investigated theoretically by analyzing simple discrete stochastic models. The
translocation dynamics is viewed as a sequence of two events: motion of the
folded segment through the channel followed by the linear part of the polymer.
The transition rates vary for the folded and linear segments because of
different interactions between the polymer molecule and the pore. It is shown
that the translocation time depends non-monotonously on the length of the
folded segment for short polymers and weak external fields, while it becomes
monotonous for long molecules and large fields. Also, there is a critical
interaction between the polymers and the pore that separates two dynamic
regimes. For stronger interactions the folded polymer moves slower, while for
weaker interactions the linear chain translocation is the fastest. In addition,
our calculations show that the folding does not change the translocation
scaling properties of the polymer. These phenomena can be explained by the
interplay between the translocation distances and transition rates for the
folded and linear segments of the polymer. Theoretical results are applied for
analysis of experimental translocations through solid-state nanopores.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 16:00:59 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Kotsev",
"Stanislav",
""
],
[
"Kolomeisky",
"Anatoly B.",
""
]
] |
0708.1321 | Mathias Drton | Mathias Drton, Thomas S. Richardson | Graphical methods for efficient likelihood inference in Gaussian
covariance models | Major revision; to appear in Journal of Machine Learning Research | null | null | null | math.ST stat.TH | null | In graphical modelling, a bi-directed graph encodes marginal independences
among random variables that are identified with the vertices of the graph. We
show how to transform a bi-directed graph into a maximal ancestral graph that
(i) represents the same independence structure as the original bi-directed
graph, and (ii) minimizes the number of arrowheads among all ancestral graphs
satisfying (i). Here the number of arrowheads of an ancestral graph is the
number of directed edges plus twice the number of bi-directed edges. In
Gaussian models, this construction can be used for more efficient iterative
maximization of the likelihood function and to determine when maximum
likelihood estimates are equal to empirical counterparts.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 19:33:00 GMT"
},
{
"version": "v2",
"created": "Tue, 25 Mar 2008 19:25:42 GMT"
}
] | 2008-03-25T00:00:00 | [
[
"Drton",
"Mathias",
""
],
[
"Richardson",
"Thomas S.",
""
]
] |
0708.1322 | Mark Van Raamsdonk | Moshe Rozali, Hsien-Hang Shieh, Mark Van Raamsdonk and Jackson Wu | Cold Nuclear Matter In Holographic QCD | 31 pages, LaTeX, 1 figure, v2: some formulae corrected, qualitative
results unchanged | JHEP0801:053,2008 | 10.1088/1126-6708/2008/01/053 | null | hep-th hep-ph nucl-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the Sakai-Sugimoto model of holographic QCD at zero temperature and
finite chemical potential. We find that as the baryon chemical potential is
increased above a critical value, there is a phase transition to a nuclear
matter phase characterized by a condensate of instantons on the probe D-branes
in the string theory dual. As a result of electrostatic interactions between
the instantons, this condensate expands towards the UV when the chemical
potential is increased, giving a holographic version of the expansion of the
Fermi surface. We argue based on properties of instantons that the nuclear
matter phase is necessarily inhomogeneous to arbitrarily high density. This
suggests an explanation of the "chiral density wave" instability of the quark
Fermi surface in large N_c QCD at asymptotically large chemical potential. We
study properties of the nuclear matter phase as a function of chemical
potential beyond the transition and argue in particular that the model can be
used to make a semi-quantitative prediction of the binding energy per nucleon
for nuclear matter in ordinary QCD.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 19:58:41 GMT"
},
{
"version": "v2",
"created": "Thu, 9 Aug 2007 23:33:41 GMT"
},
{
"version": "v3",
"created": "Thu, 25 Oct 2007 01:55:56 GMT"
},
{
"version": "v4",
"created": "Mon, 8 Sep 2008 21:50:56 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Rozali",
"Moshe",
""
],
[
"Shieh",
"Hsien-Hang",
""
],
[
"Van Raamsdonk",
"Mark",
""
],
[
"Wu",
"Jackson",
""
]
] |
0708.1323 | Nicholas Sterling | N. C. Sterling (1), Harriet L. Dinerstein (2), T. R. Kallman (1) ((1)
NASA Goddard Space Flight Center; (2) University of Texas at Austin) | A Large-Scale Survey of Neutron-Capture Element Abundances in Planetary
Nebulae | 8 pages, 2 figures. To appear in "Asymmetrical Planetary Nebulae IV,"
eds. R. L. M. Corradi, A. Manchado & N. Soker | null | null | null | astro-ph | null | We present results from the first large-scale survey of neutron(n)-capture
element abundances in planetary nebulae (PNe). This survey was motivated by the
fact that a PN may be enriched in n-capture elements if its progenitor star
experienced s-process nucleosynthesis during the asymptotic giant branch (AGB)
phase. [Kr III] 2.199 and/or [Se IV] 2.287 $\mu$m were detected in 81 PNe out
of 120 PNe, for a detection rate of nearly 70%. We derive Se and Kr abundances
or upper limits using ionization correction factors derived from
photoionization models. A significant range is found in the Se and Kr
abundances, from near solar (no enrichment), to enriched by a factor of ten.
Our survey has increased the number of PNe with known n-capture element
abundances by an order of magnitude, enabling us to explore correlations
between s-process enrichments and other nebular and central star properties. In
particular, the Se and Kr enrichments display a positive correlation with
nebular C/O ratios, as theoretically expected. Peimbert Type I PNe and bipolar
PNe, whose progenitors are believed to be intermediate-mass stars (>3-4 M_sun),
exhibit little or no s-process enrichment. Interestingly, PNe with H-deficient
[WC] central stars do not exhibit systematically larger s-process enrichments
than other PNe, despite the fact that their central stars are enriched in C and
probably n-capture elements. Finally, the few PNe in our sample with known or
probable binary central star systems exhibit little s-process enrichment, which
may be explained if binary interactions truncated their AGB phases. We also
briefly discuss a new observational program to detect optical emission lines of
n-capture elements, and new atomic data calculations that will greatly improve
the accuracy of n-capture element abundance determinations in PNe.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 19:34:56 GMT"
}
] | 2007-08-10T00:00:00 | [
[
"Sterling",
"N. C.",
""
],
[
"Dinerstein",
"Harriet L.",
""
],
[
"Kallman",
"T. R.",
""
]
] |
0708.1324 | Marcos Rigol Madrazo | Marcos Rigol, Vanja Dunjko, Maxim Olshanii | Thermalization and its mechanism for generic isolated quantum systems | 8 pages, 6 figures, as published | Nature 452, 854-858 (17 April 2008) | 10.1038/nature06838 | null | cond-mat.stat-mech | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Time dynamics of isolated many-body quantum systems has long been an elusive
subject. Very recently, however, meaningful experimental studies of the problem
have finally become possible, stimulating theoretical interest as well.
Progress in this field is perhaps most urgently needed in the foundations of
quantum statistical mechanics. This is so because in generic isolated systems,
one expects nonequilibrium dynamics on its own to result in thermalization: a
relaxation to states where the values of macroscopic quantities are stationary,
universal with respect to widely differing initial conditions, and predictable
through the time-tested recipe of statistical mechanics. However, it is not
obvious what feature of many-body quantum mechanics makes quantum
thermalization possible, in a sense analogous to that in which dynamical chaos
makes classical thermalization possible. For example, dynamical chaos itself
cannot occur in an isolated quantum system, where time evolution is linear and
the spectrum is discrete. Underscoring that new rules could apply in this case,
some recent studies even suggested that statistical mechanics may give wrong
predictions for the outcomes of relaxation in such systems. Here we demonstrate
that an isolated generic quantum many-body system does in fact relax to a state
well-described by the standard statistical mechanical prescription. Moreover,
we show that time evolution itself plays a merely auxiliary role in relaxation
and that thermalization happens instead at the level of individual eigenstates,
as first proposed by J.M. Deutsch and M. Srednicki. A striking consequence of
this eigenstate thermalization scenario is that the knowledge of a single
many-body eigenstate suffices to compute thermal averages-any eigenstate in the
microcanonical energy window will do, as they all give the same result.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 20:00:10 GMT"
},
{
"version": "v2",
"created": "Thu, 11 Jun 2009 00:29:29 GMT"
}
] | 2009-06-11T00:00:00 | [
[
"Rigol",
"Marcos",
""
],
[
"Dunjko",
"Vanja",
""
],
[
"Olshanii",
"Maxim",
""
]
] |
0708.1325 | Gabriel Shaughnessy | Vernon Barger, Wai-Yee Keung, Gabe Shaughnessy, Adam Tregre | High energy neutrinos from neutralino annihilations in the Sun | 45 pages, 18 figures and 5 tables, PRD version | Phys.Rev.D76:095008,2007 | 10.1103/PhysRevD.76.095008 | MADPH-07-1494 | hep-ph astro-ph | null | Neutralino annihilations in the Sun to weak boson and top quark pairs lead to
high-energy neutrinos that can be detected by the IceCube and KM3 experiments
in the search for neutralino dark matter. We calculate the neutrino signals
from real and virtual WW, ZZ, Zh, and $t \bar t$ production and decays,
accounting for the spin-dependences of the matrix elements, which can have
important influences on the neutrino energy spectra. We take into account
neutrino propagation including neutrino oscillations, matter-resonance,
absorption, and nu_tau regeneration effects in the Sun and evaluate the
neutrino flux at the Earth. We concentrate on the compelling Focus Point (FP)
region of the supergravity model that reproduces the observed dark matter relic
density. For the FP region, the lightest neutralino has a large bino-higgsino
mixture that leads to a high neutrino flux and the spin-dependent neutralino
capture rate in the Sun is enhanced by 10^3 over the spin-independent rate. For
the standard estimate of neutralino captures, the muon signal rates in IceCube
are identifiable over the atmospheric neutrino background for neutralino masses
above M_Z up to 400 GeV.
| [
{
"version": "v1",
"created": "Fri, 10 Aug 2007 00:26:52 GMT"
},
{
"version": "v2",
"created": "Fri, 2 Nov 2007 16:51:33 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Barger",
"Vernon",
""
],
[
"Keung",
"Wai-Yee",
""
],
[
"Shaughnessy",
"Gabe",
""
],
[
"Tregre",
"Adam",
""
]
] |
0708.1326 | Andrew Gould | Andrew Gould | Investigation of the Contamination of the Gould (2003) Halo Sample | 5 pages including 9 figures. Full resolution available at
http://www.astronomy.ohio-state.edu/~gould/contam.ps.gz | null | null | null | astro-ph | null | A recent astroph posting argued that the Gould (2003a) halo sample is
substantially contaminated with thick-disk stars, which would then ``wash out''
any signature of granularity in the halo velocity distribution due to streams.
If correct, this would imply that the limits placed by Gould (2003b) on streams
are not valid. Here I investigate such contamination using six different
indicators: (1) morphology of the underlying reduced proper motion diagram used
to select halo stars; (2) comparison of kinematic and parallax-based distance
scales; (3) comparison of derived halo parameters for the Gould (2003a) sample
with other determinations; (4) a precision color-color diagram for a random
subsample; (5) the 3-dimensional velocity distribution of a random subsample;
(6) metallicity distribution versus kinematic cuts on a random subsample. I
estimate that the contamination is of order 2%. Thus, the upper limits on the
density of nearby streams derived by Gould (2003b) remain valid. In particular,
at 95% confidence, no more than 5% of local halo stars (within about 300 pc)
are in any one coherent stream. Determining whether or not this local
measurement is consistent with CDM remains an outstanding question.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 20:01:03 GMT"
}
] | 2007-08-13T00:00:00 | [
[
"Gould",
"Andrew",
""
]
] |
0708.1327 | Matthew Walker | Mario Mateo, Edward W. Olszewski, and Matthew G. Walker | The Velocity Dispersion Profile of the Remote Dwarf Spheroidal Galaxy
Leo I: A Tidal Hit and Run? | ApJ accepted, 23 figures, access paper as a pdf file at
http://www.astro.lsa.umich.edu/~mmateo/research.html | null | 10.1086/522326 | null | astro-ph | null | (abridged) We present kinematic results for a sample of 387 stars located
near Leo I based on spectra obtained with the MMT's Hectochelle spectrograph
near the MgI/Mgb lines. We estimate the mean velocity error of our sample to be
2.4 km/s, with a systematic error of < 1 km/s. We produce a final sample of 328
Leo I red giant members, from which we measure a mean heliocentric radial
velocity of 282.9 +/- 0.5 km/s, and a mean radial velocity dispersion of 9.2
+/- 0.4 km/s for Leo I. The dispersion profile of Leo I is flat out to beyond
its classical `tidal' radius. We fit the profile to a variety of equilibrium
dynamical models and can strongly rule out models where mass follows light.
Two-component Sersic+NFW models with tangentially anisotropic velocity
distributions fit the dispersion profile well, with isotropic models ruled out
at a 95% confidence level. The mass and V-band mass-to-light ratio of Leo I
estimated from equilibrium models are in the ranges 5-7 x 10^7 M_sun and 9-14
(solar units), respectively, out to 1 kpc from the galaxy center. Leo I members
located outside a `break radius' (about 400 arcsec = 500 pc) exhibit
significant velocity anisotropy, whereas stars interior appear to have
isotropic kinematics. We propose the break radius represents the location of
the tidal radius of Leo I at perigalacticon of a highly elliptical orbit. Our
scenario can account for the complex star formation history of Leo I, the
presence of population segregation within the galaxy, and Leo I's large outward
velocity from the Milky Way. The lack of extended tidal arms in Leo I suggests
the galaxy has experienced only one perigalactic passage with the Milky Way,
implying that Leo I may have been injected into its present orbit by a third
body a few Gyr before perigalacticon.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 20:07:53 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Mateo",
"Mario",
""
],
[
"Olszewski",
"Edward W.",
""
],
[
"Walker",
"Matthew G.",
""
]
] |
0708.1328 | Sarah Bailey Frick | Sarah Bailey Frick | Limited scope adic transformations | 29 pages, 12 figures | null | null | null | math.DS | null | We introduce a family of adic transformations on diagrams that are
nonstationary and nonsimple. This family includes some previously studied adic
transformations. We relate the dimension group of each these diagrams to the
dynamical system determined by the adic transformation on the infinite edge
paths, and we explicitly compute the dimension group for a subfamily. We also
determine the ergodic adic invariant probability measures for this subfamily,
and show that each system of the subfamily is loosely Bernoulli. We also give
examples of particular adic transformations with roots of unity as well as one
which is totally ergodic called the Euler adic. We also show that the Euler
adic is loosely Bernoulli.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 20:16:00 GMT"
}
] | 2007-08-13T00:00:00 | [
[
"Frick",
"Sarah Bailey",
""
]
] |
0708.1329 | Micah Warren | Micah Warren and Yu Yuan | Explicit gradient estimates for minimal Lagrangian surfaces of dimension
two | 14 pages | null | null | null | math.AP math.DG | null | We derive explicit, uniform, a priori interior Hessian and gradient estimates
for special Lagrangian equations of all phases in dimension two.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 20:27:56 GMT"
}
] | 2007-08-13T00:00:00 | [
[
"Warren",
"Micah",
""
],
[
"Yuan",
"Yu",
""
]
] |
0708.1330 | Rolando Somma | Rolando D. Somma, Sergio Boixo | Parameter Estimation with Mixed-State Quantum Computation | 12 pages. Improved introduction and technical details moved to
Appendix | Phys. Rev. A 77, 052320 (2008) | 10.1103/PhysRevA.77.052320 | null | quant-ph | null | We present a quantum algorithm to estimate parameters at the quantum
metrology limit using deterministic quantum computation with one bit. When the
interactions occurring in a quantum system are described by a Hamiltonian $H=
\theta H_0$, we estimate $\theta$ by zooming in on previous estimations and by
implementing an adaptive Bayesian procedure. The final result of the algorithm
is an updated estimation of $\theta$ whose variance has been decreased in
proportion to the time of evolution under H. For the problem of estimating
several parameters, we implement dynamical-decoupling techniques and use the
results of single parameter estimation. The cases of discrete-time evolution
and reference-frame alignment are also discussed within the adaptive approach.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 20:30:06 GMT"
},
{
"version": "v2",
"created": "Tue, 15 Apr 2008 18:51:08 GMT"
}
] | 2008-07-03T00:00:00 | [
[
"Somma",
"Rolando D.",
""
],
[
"Boixo",
"Sergio",
""
]
] |
0708.1331 | Bradley E. Schaefer | Teresa Ashcraft and Bradley E. Schaefer | Are There Any Redshift >8 Gamma-Ray Bursts in the BATSE Catalog? | ApJ in press, 18 pages | null | 10.1086/522577 | null | astro-ph | null | Several luminosity indicators have been found for Gamma-Ray Bursts (GRBs)
wherein measurable light curve and spectral properties are well-correlated with
the peak luminosity. Several papers have each applied one different luminosity
relation to find redshifts for BATSE GRBs and claim to identify specific bursts
with z>8. The existence of such high redshift events is not surprising, as
BATSE has enough sensitivity to see them and GRBs are expected out to the
redshift of the first star formation. To improve results we used five
luminosity relations with updated calibrations to determine redshifts with
error bars. Combining these relations, we calculated the redshifts of 36 BATSE
GRBs with claimed z>8. Our results include 13 bursts with our derived best
redshift z_best>8, which looks promising at first. But the calculated redshift
uncertainties are significantly large in these selected cases. With only one
exception, all of our bursts have z_1siglow<9. The one exception (BATSE trigger
2035) is likely a short duration burst at z>~4. Our best case for a very high
redshift event is BATSE trigger 3142 with z_best>20 and z_1siglow=8.9, however
we can only say z>4.1 at the two-sigma confidence level. In all, we cannot
point toward any one BATSE burst as confidently having z>8. One implication is
to greatly weaken prior claims that GRBs have a steeply rising rate-density out
to high redshifts.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 20:34:36 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Ashcraft",
"Teresa",
""
],
[
"Schaefer",
"Bradley E.",
""
]
] |
0708.1332 | Daniela Dragoman | Daniela Dragoman | Quantum Electric Circuits Analogous to Ballistic Conductors | 14 pages | null | 10.1063/1.2907978 | null | quant-ph | null | The conductance steps in a constricted two-dimensional electron gas and the
minimum conductivity in graphene are related to a new uncertainty relation
between electric charge and conductance in a quantized electric circuit that
mimics the electric transport in mesoscopic systems. This uncertainty relation
makes specific use of the discreteness of electric charge. Quantum electric
circuits analogous to both constricted two-dimensional electron gas and
graphene are introduced. In the latter case a new insight into the origin of
minimum conductivity is obtained.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 20:43:40 GMT"
},
{
"version": "v2",
"created": "Wed, 28 Nov 2007 19:18:56 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Dragoman",
"Daniela",
""
]
] |
0708.1333 | Ramin G. Daghigh | Ramin G. Daghigh and Michael Green | The Highly Damped Quasinormal Modes of Extremal Reissner-Nordstr\"om and
Reissner-Nordstr\"om-de Sitter Black Holes | 17 pages, 5 figures | Class.Quant.Grav.25:055001,2008 | 10.1088/0264-9381/25/5/055001 | null | gr-qc | null | We analyze in detail the highly damped quasinormal modes of $D$-dimensional
extremal Reissner-Nordstr$\ddot{\rm{o}}$m and
Reissner-Nordstr$\ddot{\rm{o}}$m-de Sitter black holes. We only consider the
extremal case where the event horizon and the Cauchy inner horizon coincide. We
show that, even though the topology of the Stokes/anti-Stokes lines in the
extremal case is different than the non-extremal case, the highly damped
quasinormal mode frequencies of extremal black holes match exactly with the
extremal limit of the non-extremal black hole quasinormal mode frequencies.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 20:44:08 GMT"
},
{
"version": "v2",
"created": "Thu, 3 Apr 2008 20:04:05 GMT"
}
] | 2011-03-28T00:00:00 | [
[
"Daghigh",
"Ramin G.",
""
],
[
"Green",
"Michael",
""
]
] |
0708.1334 | Daniel Farley | Daniel Farley | A Proof that Thompson's Groups have Infinitely Many Relative Ends | 11 pages, 1 figure | null | null | null | math.GR | null | We show that each of Thompson's groups F, T, and V have infinitely many ends
relative to certain subgroups. We go on to show that T and V both have Serre's
property FA, i.e., any action of T or V on a tree will have a fixed point. (The
proof of the latter statement was originally due to Ken Brown, and our proof is
based on his notes.)
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 20:48:05 GMT"
}
] | 2007-08-13T00:00:00 | [
[
"Farley",
"Daniel",
""
]
] |
0708.1335 | Joseph Masiero | Joseph Masiero, Klaus Hodapp, Dave Harrington, Haosheng Lin (IfA,
Hawaii) | Commissioning of the Dual-Beam Imaging Polarimeter for the UH 88-inch
telescope | Accepted to PASP | null | 10.1086/522379 | null | astro-ph | null | In this paper we present the design, calibration method, and initial results
of the Dual-Beam Imaging Polarimeter (DBIP). This new instrument is designed to
measure the optical polarization properties of point sources, in particular
Main Belt asteroids. This instrument interfaces between the Tek 2048x2048
camera and the University of Hawaii's 88-inch telescope, and is available for
facility use. Using DBIP we are able to measure linear polarization with a
1-sigma Poisson signal noise of 0.03% per measurement and a systematic error of
order 0.06% +/- 0.02%. Additionally, we discuss measurements of the
polarization of the asteroid 16 Psyche which were taken as part of the
instrument commissioning. We confirm Psyche's negative polarization of -1.037%
+/- 0.006% but find no significant modulation of the signal with rotation above
the 0.05% polarization level.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 20:51:07 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Masiero",
"Joseph",
"",
"IfA,\n Hawaii"
],
[
"Hodapp",
"Klaus",
"",
"IfA,\n Hawaii"
],
[
"Harrington",
"Dave",
"",
"IfA,\n Hawaii"
],
[
"Lin",
"Haosheng",
"",
"IfA,\n Hawaii"
]
] |
0708.1336 | Jae Youn Lee | J. Y. Lee and M. Schick | Dependence of the energies of fusion on the intermembrane separation:
optimal and constrained | 30 pages including cover, abstract, and 4 figures accepted, J. Chem.
Phys | null | 10.1063/1.2766945 | null | cond-mat.soft cond-mat.stat-mech | null | We calculate the characteristic energies of fusion between planar bilayers as
afunction of the distance between them, measured from the
hydrophobic/hydrophilic interface of one of the two nearest, cis, leaves to the
other. The two leaves of each bilayer are of equal composition; 0.6 volume
fraction of a lamellar-forming amphiphile, such as dioleoylphosphatidylcholine,
and 0.4 volume fraction of a hexagonal-forming amphiphile, such as
dioleoylphosphatidylethanolamine. Self-consistent field theory is employed to
solve the model. We find that the largest barrier to fusion is that to create
the metastable stalk. This barrier is the smallest, about 14.6 $k_BT$, when the
bilayers are at a distance about 20 percent greater than the thickness of a
single leaf, a distance which would correspond to between two and three
nanometers for typical bilayers. The very size of the protein machinery which
brings the membranes together can prevent them from reaching this optimum
separation. For even modestly larger separations, we find a linear rate of
increase of the free energy with distance between bilayers for the metastable
stalk itself and for the barrier to the creation of this stalk. We estimate
these rates for biological membranes to be about 7.1 $k_BT$/nm and 16.7
$k_BT$/nm respectively. The major contribution to this rate comes from the
increased packing energy associated with the hydrophobic tails. From this we
estimate, for the case of hemagglutinin, a free energy of 38 k_BT for the
metastable stalk itself, and a barrier to create it of 73 k_BT. Such a large
barrier would require that more than a single hemagglutinin molecule be
involved in the fusion process, as is observed.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 20:51:11 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Lee",
"J. Y.",
""
],
[
"Schick",
"M.",
""
]
] |
0708.1337 | David Poulin | Matthew Leifer and David Poulin | Quantum Graphical Models and Belief Propagation | 58 pages, 9 figures | Ann. Phys. 323 1899 (2008) | 10.1016/j.aop.2007.10.001 | null | quant-ph | null | Belief Propagation algorithms acting on Graphical Models of classical
probability distributions, such as Markov Networks, Factor Graphs and Bayesian
Networks, are amongst the most powerful known methods for deriving
probabilistic inferences amongst large numbers of random variables. This paper
presents a generalization of these concepts and methods to the quantum case,
based on the idea that quantum theory can be thought of as a noncommutative,
operator-valued, generalization of classical probability theory. Some novel
characterizations of quantum conditional independence are derived, and
definitions of Quantum n-Bifactor Networks, Markov Networks, Factor Graphs and
Bayesian Networks are proposed. The structure of Quantum Markov Networks is
investigated and some partial characterization results are obtained, along the
lines of the Hammersely-Clifford theorem. A Quantum Belief Propagation
algorithm is presented and is shown to converge on 1-Bifactor Networks and
Markov Networks when the underlying graph is a tree. The use of Quantum Belief
Propagation as a heuristic algorithm in cases where it is not known to converge
is discussed. Applications to decoding quantum error correcting codes and to
the simulation of many-body quantum systems are described.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 20:54:21 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Leifer",
"Matthew",
""
],
[
"Poulin",
"David",
""
]
] |
0708.1338 | Tracey Jane Turner | T. J. Turner, L. Miller, J. N. Reeves, S. B. Kraemer | The Variable X-ray Spectrum of Markarian 766 - II. Time-Resolved
Spectroscopy | null | null | 10.1051/0004-6361:20077947 | null | astro-ph | null | CONTEXT: The variable X-ray spectra of AGN systematically show steep
power-law high states and hard-spectrum low states. The hard low state has
previously been found to be a component with only weak variability. The origin
of this component and the relative importance of effects such as absorption and
relativistic blurring are currently not clear. AIMS: In a follow-up of previous
principal components analysis, we aim to determine the relative importance of
scattering and absorption effects on the time-varying X-ray spectrum of the
narrow-line Seyfert 1 galaxy Mrk~766. METHODS: Time-resolved spectroscopy,
slicing XMM and Suzaku data down to 25 ks elements, is used to investigate
whether absorption or scattering components dominate the spectral variations in
Mrk 766.Time-resolved spectroscopy confirms that spectral variability in Mrk
766 can be explained by either of two interpretations of principal components
analysis. Detailed investigation confirm rapid changes in the relative
strengths of scattered and direct emission or rapid changes in absorber
covering fraction provide good explanations of most of the spectral
variability. However, a strong correlation between the 6.97 keV absorption line
and the primary continuum together with rapid opacity changes show that
variations in a complex and multi-layered absorber, most likely a disk wind,
are the dominant source of spectral variability in Mrk 766
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 21:04:02 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Turner",
"T. J.",
""
],
[
"Miller",
"L.",
""
],
[
"Reeves",
"J. N.",
""
],
[
"Kraemer",
"S. B.",
""
]
] |
0708.1339 | Moshe Schechter | Moshe Schechter | Superconducting fluctuations in small grains - the Universal Hamiltonian
and the reduced BCS model | Contribution to the proceedings of "Fluctuations and phase
transitions in superconductors", Nazareth Ilit, Israel, June 10-14, 2007 | Physica C 468, 350 (2008) | 10.1016/j.physc.2007.08.025 | null | cond-mat.mes-hall cond-mat.supr-con | null | Small superconducting grains are discussed in the frameworks of both the
reduced BCS Hamiltonian and the Universal Hamiltonian. It is shown that
fluctuations of electrons in levels far from the Fermi energy dominate
superconducting properties in small and ultrasmall grains. Experimental
consequences related to the spin susceptibility and persistent currents of
grains and rings with weak electron-electron interactions are discussed.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 21:04:08 GMT"
}
] | 2008-06-12T00:00:00 | [
[
"Schechter",
"Moshe",
""
]
] |
0708.1340 | Eric Josef Ribeiro Parteli | E. J. R. Parteli, O. Dur\'an and H. J. Herrmann | Reply to "Comment on `Minimal size of a barchan dune' " | 6 pages and 2 figures. Submitted to Physical Review E | null | 10.1103/PhysRevE.76.063302 | null | cond-mat.other | null | We reply to the comment by Andreotti and Claudin (submitted to Phys. Rev. E,
arXiv:0705.3525) on our paper ``Minimal Size of a Barchan Dune'' [Phys. Rev. E
{\bf{75,}} 011301 (2007)]. We show that the equations of the dune model used in
our calculations are self-consistent and effectively lead to a dependence of
the minimal dune size on the wind speed through the saturation length.
Furthermore, we show that Meridiani Planum ripples are probably not a good
reference to estimate the grain size of Martian dune sands: the soil in the
ripple troughs at the landing site is covered with nonerodible elements
(``blueberries''), which increase the minimal threshold for saltation by a
factor of 2.0. We conclude that, in the absence of large fragments as the ones
found at the landing site, basaltic grains of diameter $d=500 \pm 100 {\mu}$m
that compose the large, typical dark Martian dunes [K. S. Edgett and P. R.
Christensen, J. Geophys. Res. {\bf{96,}} 22765 (1991)] probably saltate during
the strongest storms on Mars. We also show that the wind friction speed
$u_{\ast} \approx 3.0$ m/s that we found from the calculations of Martian dunes
is within the values of maximum wind speeds that occur during Martian storms a
few times a decade [R. E. Arvidson {\em{et al.}}, Science {\bf{222,}} 463
(1983); H. J. Moore, J. Geophys. Res. {\bf{90,}} 163 (1985); R. Sullivan
{\em{et al.}}, Nature {\bf{436,}} 58 (2005); D. J. Jerolmack {\em{et al.}}, J.
Geophys. Res. {\bf{111,}} E12S02 (2006)]. In this manner, the dune model
predicts that Martian dunes can be formed under present Martian conditions,
with no need to assume other conditions of wind and atmosphere that could have
prevailed in the past.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 21:07:48 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Parteli",
"E. J. R.",
""
],
[
"Durán",
"O.",
""
],
[
"Herrmann",
"H. J.",
""
]
] |
0708.1341 | David Hsu | David Hsu, Murielle Hsu, He Huang and Erwin B. Montgomery, Jr | An algorithm for detecting oscillatory behavior in discretized data: the
damped-oscillator oscillator detector | 20 pages, 6 figures | null | null | null | q-bio.QM q-bio.NC | null | We present a simple algorithm for detecting oscillatory behavior in discrete
data. The data is used as an input driving force acting on a set of simulated
damped oscillators. By monitoring the energy of the simulated oscillators, we
can detect oscillatory behavior in data. In application to in vivo deep brain
basal ganglia recordings, we found sharp peaks in the spectrum at 20 and 70 Hz.
The algorithm is also compared to the conventional fast Fourier transform and
circular statistics techniques using computer generated model data, and is
found to be comparable to or better than fast Fourier transform in test cases.
Circular statistics performed poorly in our tests.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 21:14:11 GMT"
}
] | 2012-08-27T00:00:00 | [
[
"Hsu",
"David",
""
],
[
"Hsu",
"Murielle",
""
],
[
"Huang",
"He",
""
],
[
"Montgomery,",
"Erwin B.",
"Jr"
]
] |
0708.1342 | Luiz Agostinho Ferreira | P. E. G. Assis and L. A. Ferreira | The Bullough-Dodd model coupled to matter fields | 48 pages, 3 eps figures, latex | Nucl.Phys.B800:409-449,2008 | 10.1016/j.nuclphysb.2008.01.004 | null | hep-th math-ph math.MP nlin.SI | null | The Bullough-Dodd model is an important two dimensional integrable field
theory which finds applications in physics and geometry. We consider a
conformally invariant extension of it, and study its integrability properties
using a zero curvature condition based on the twisted Kac-Moody algebra
A_2^{(2)}. The one and two-soliton solutions as well as the breathers are
constructed explicitly . We also consider integrable extensions of the
Bullough-Dodd model by the introduction of spinor (matter) fields. The
resulting theories are conformally invariant and present local internal
symmetries. All the one-soliton solutions, for two examples of those models,
are constructed using an hybrid of the dressing and Hirota methods. One model
is of particular interest because it presents a confinement mechanism for a
given conserved charge inside the solitons.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 21:27:48 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Assis",
"P. E. G.",
""
],
[
"Ferreira",
"L. A.",
""
]
] |
0708.1343 | Heide Gluesing-Luerssen | Heide Gluesing-Luerssen, Fai-Lung Tsang | A Matrix Ring Description for Cyclic Convolutional Codes | null | null | null | null | cs.IT math.IT math.RA | null | In this paper, we study convolutional codes with a specific cyclic structure.
By definition, these codes are left ideals in a certain skew polynomial ring.
Using that the skew polynomial ring is isomorphic to a matrix ring we can
describe the algebraic parameters of the codes in a more accessible way. We
show that the existence of such codes with given algebraic parameters can be
reduced to the solvability of a modified rook problem. It is our strong belief
that the rook problem is always solvable, and we present solutions in
particular cases.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 21:35:15 GMT"
}
] | 2007-08-13T00:00:00 | [
[
"Gluesing-Luerssen",
"Heide",
""
],
[
"Tsang",
"Fai-Lung",
""
]
] |
0708.1344 | James Jenkins Jr | Andre de Gouvea, James Jenkins (Northwestern University) | A Survey of Lepton Number Violation Via Effective Operators | 34 pages, 10 eps figures, 1 table | Phys.Rev.D77:013008,2008 | 10.1103/PhysRevD.77.013008 | NUHEP-TH/07-10 | hep-ph | null | We survey 129 lepton number violating effective operators, consistent with
the minimal Standard Model gauge group and particle content, of mass dimension
up to and including eleven. Upon requiring that each one radiatively generates
the observed neutrino masses, we extract an associated characteristic cutoff
energy scale which we use to calculate other observable manifestations of these
operators for a number of current and future experimental probes, concentrating
on lepton number violating phenomena. These include searches for neutrinoless
double-beta decay and rare meson, lepton, and gauge boson decays. We also
consider searches at hadron/lepton collider facilities in anticipation of the
LHC and the future ILC. We find that some operators are already disfavored by
current data, while more are ripe to be probed by next-generation experiments.
We also find that our current understanding of lepton mixing disfavors a subset
of higher dimensional operators. While neutrinoless double-beta decay is the
most promising signature of lepton number violation for the majority of
operators, a handful is best probed by other means. We argue that a combination
of constraints from various independent experimental sources will help to
pinpoint the ``correct'' model of neutrino mass, or at least aid in narrowing
down the set of possibilities.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 21:49:44 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"de Gouvea",
"Andre",
"",
"Northwestern University"
],
[
"Jenkins",
"James",
"",
"Northwestern University"
]
] |
0708.1345 | Leandro Malard M | L. M. Malard, J. Nilsson, D. C. Elias, J. C. Brant, F. Plentz, E. S.
Alves, A. H. Castro Neto and M. A. Pimenta | Probing the Electronic Structure of Bilayer Graphene by Raman Scattering | 4 pages, 4 figures | Phys. Rev. B 76, 201401(R) (2007) | 10.1103/PhysRevB.76.201401 | null | cond-mat.mtrl-sci cond-mat.mes-hall | null | The electronic structure of bilayer graphene is investigated from a resonant
Raman study using different laser excitation energies. The values of the
parameters of the Slonczewski-Weiss-McClure model for graphite are measured
experimentally and some of them differ significantly from those reported
previously for graphite, specially that associated with the difference of the
effective mass of electrons and holes. The splitting of the two TO phonon
branches in bilayer graphene is also obtained from the experimental data. Our
results have implications for bilayer graphene electronic devices.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 21:50:35 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Malard",
"L. M.",
""
],
[
"Nilsson",
"J.",
""
],
[
"Elias",
"D. C.",
""
],
[
"Brant",
"J. C.",
""
],
[
"Plentz",
"F.",
""
],
[
"Alves",
"E. S.",
""
],
[
"Neto",
"A. H. Castro",
""
],
[
"Pimenta",
"M. A.",
""
]
] |
0708.1346 | Matthew Roberts | Gary T. Horowitz and Matthew M. Roberts | Counting the Microstates of a Kerr Black Hole | 10 pages, 2 figures | Phys.Rev.Lett.99:221601,2007 | 10.1103/PhysRevLett.99.221601 | null | hep-th gr-qc | null | We show that an extremal Kerr black hole, appropriately lifted to M-theory,
can be transformed to a Kaluza-Klein black hole in M-theory, or a D0-D6 charged
black hole in string theory. Since all the microstates of the latter have
recently been identified, one can exactly reproduce the entropy of an extremal
Kerr black hole. We also show that the topology of the event horizon is not
well defined in M-theory.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 22:16:47 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Horowitz",
"Gary T.",
""
],
[
"Roberts",
"Matthew M.",
""
]
] |
0708.1347 | Irit Maor | Irit Maor, Harsh Mathur and Tanmay Vachaspati | Quantized Non-Abelian Monopoles on S^3 | 18 pages, 5 figures. Minor changes, reference list updated | Phys.Rev.D76:105013,2007 | 10.1103/PhysRevD.76.105013 | null | hep-th hep-lat hep-ph | null | A possible electric-magnetic duality suggests that the confinement of
non-Abelian electric charges manifests itself as a perturbative quantum effect
for the dual magnetic charges. Motivated by this possibility, we study vacuum
fluctuations around a non-Abelian monopole-antimonopole pair treated as point
objects with charges g=\pm n/2 (n=1,2,...), and placed on the antipodes of a
three sphere of radius R. We explicitly find all the fluctuation modes by
linearizing and solving the Yang-Mills equations about this background field on
a three sphere. We recover, generalize and extend earlier results, including
those on the stability analysis of non-Abelian magnetic monopoles. We find that
for g \ge 1 monopoles there is an unstable mode that tends to squeeze magnetic
flux in the angular directions. We sum the vacuum energy contributions of the
fluctuation modes for the g=1/2 case and find oscillatory dependence on the
cutoff scale. Subject to certain assumptions, we find that the contribution of
the fluctuation modes to the quantum zero point energy behaves as -R^{-2/3} and
hence decays more slowly than the classical -R^{-1} Coulomb potential for large
R. However, this correction to the zero point energy does not agree with the
linear growth expected if the monopoles are confined.
| [
{
"version": "v1",
"created": "Fri, 10 Aug 2007 18:07:54 GMT"
},
{
"version": "v2",
"created": "Mon, 20 Aug 2007 22:12:53 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Maor",
"Irit",
""
],
[
"Mathur",
"Harsh",
""
],
[
"Vachaspati",
"Tanmay",
""
]
] |
0708.1348 | Tien Quang Nguyen | Nguyen Tien Quang | On Gr-Functors between Gr-Categories: Obstruction theory for Gr-Functors
of the type $(\varphi,f)$ | 12 pager, For reduction, the abstract and subsection 1.1 have been
edited; section 2 and the beginning of section 5 have been omitted. The
definition of the functors of the type $(\varphi,f)$ has been introduced in
order to represent some theorems and their proofs in other words | null | null | null | math.CT | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Each Gr-functor of the type $(\varphi,f)$ of a Gr-category of the type
$(\Pi,\C)$ has the obstruction be an element $\overline{k}\in H^3(\Pi,\C).$
When this obstruction vanishes, there exists a bijection between congruence
classes of Gr-functors of the type $(\varphi,f)$ and the cohomology group
$H^2(\Pi,\C).$ Then the relation of Gr-category theory and the group extension
problem can be established and used to prove that each Gr-category is
Gr-equivalent to a strict one.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 22:27:52 GMT"
},
{
"version": "v2",
"created": "Sat, 18 Apr 2009 12:22:18 GMT"
}
] | 2009-04-20T00:00:00 | [
[
"Quang",
"Nguyen Tien",
""
]
] |
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