Implications of the first detection of coherent elastic neutrino-nucleus scattering (CEvNS) with Liquid Argon
O. G. Miranda D. K. Papoulias G. Sanchez Garcia O. Sanders M. Tórtola J. W. F. Valle
hep-ph
 
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        SU(2)_L ⊗ SU(2)_R ⊗ U(1)_B-L
        neutrinoless double beta decay 
        𝒞𝒫𝒞𝒫𝒯𝒫𝒯𝒞2𝒵_2Łℒet al.h.c.#1⟨ #1⟩
         
         lepton flavour violation lepton number violation CEνNS 
        
        
        
        
         
        lepton flavour violation lepton number violating SU(3)_c ⊗ SU(2)_L ⊗ U(1)_YSU(3)_c ⊗ SU(3)_L ⊗ U(1)_XSU(3)_c ⊗ SU(3)_L ⊗ U(1)_X ⊗ U(1)_N
        
        
        
        
        
        
        
        
        
        
        21SU(3) ⊗ SU(2) ⊗ U(1)
        #1#1#1#1#1#1#1#1#1#1unsrtomr@fis.cinvestav.mxdimpap@cc.uoi.grgsanchez@fis.cinvestav.mxosanders@fis.cinvestav.mxmariam@ific.uv.esvalle@ific.uv.es
          
          The CENNS-10 experiment of the COHERENT collaboration has recently reported the first detection of coherent-elastic neutrino-nucleus scattering (CEvNS) in liquid Argon with more than 3 σ significance. In this work, we exploit the new data in order to probe various interesting parameters which are of key importance to CEvNS within and beyond the Standard Model.
        
          A dedicated statistical analysis of these data shows that the current constraints are significantly improved in most cases.
        
         We derive a first measurement of the neutron rms charge radius of Argon, and also an improved determination of the weak mixing angle in the low energy regime.
        
         We also update the constraints on  neutrino non-standard interactions, electromagnetic properties and light mediators with respect to those derived from the first COHERENT-CsI data.
         Implications of the first detection of coherent elastic neutrino-nucleus scattering (CEvNS) with Liquid Argon
            J. W. F. Valle
            December 30, 2023
        ==============================================================================================================
        
        
          
        
        § INTRODUCTION
        
        
        
        Over the past few decades, neutrino physics has entered the precision era and is steadily approaching a full description of the three neutrino oscillation picture <cit.>.
        
        Although the next generation of long-baseline experiments such as DUNE and Hyper-Kamiokande will play a key role in settling the open issues, some degeneracies are likely to remain.
        
        Moreover, beyond the challenges associated to the three-neutrino parameters, such as the atmospheric octant, the presence of leptonic CP violation, the neutrino mass ordering, and the absolute scale of the neutrino mass, there are a number of less standard, but important, neutrino properties to pin down.
        
        The discovery of coherent elastic scattering of neutrinos off nuclei at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL) using a CsI detector <cit.> has opened new ways to study key weak interaction parameters, such as the electroweak mixing angle <cit.> and the nuclear form factors <cit.>, as well as to probe novel neutrino properties beyond the Standard Model (SM) <cit.>. Among the most interesting possibilities, are those addressing non-standard interactions (NSI) <cit.>, electromagnetic neutrino properties <cit.>, sterile neutrinos <cit.>, new light mediators <cit.> and dark matter <cit.>.
        
        The study of these scenarios would provide important hints for physics beyond the current three-massive-neutrino paradigm of elementary particles.
        
        In fact, many of them may be regarded as implications of the very existence of neutrino masses themselves. 
        
        Moreover, coherent elastic neutrino-nucleus scattering (CEvNS) experiments provide new ways to understand neutrino cross sections, crucial for establishing the robustness of oscillation experiments and their interpretation.
        
        
        Here we show how the recent confirmation of the CEvNS process by the COHERENT collaboration using a 24 kg  liquid Argon (LAr) detector at the SNS <cit.>, after collecting 6.12 GWh data substantially improves the sensitivity of a number of key weak interaction measurements. The reported results have shown a greater than 3 σ preference in favor of CEvNS. 
        
        This paper is organized as follows. In Sec. <ref> we set up the notation and summarize briefly the CEvNS formalism. Then, in Sec. <ref> we present the sensitivities on various parameters of the electroweak interaction in the SM  and beyond, obtained using the recent CENNS-10 results. Finally, our main conclusions are summarized in Sec. <ref>.
        
        
        
        § BASICS
        
        
        Proposed more than forty years ago by Freedman <cit.>,
        this neutral current process is characterized by a cross section that increases as N^2, where N being the number of neutrons in the nucleus:
        
        
            (d σ/dT_A)_SM = G_F^2 m_A/2 π  (𝒬^V_W)^2 [ 2 - 2 T_A/E_ν - m_A T_A/E_ν^2]    ,
        
        where G_F denotes the Fermi constant, T_A is the nucleus kinetic energy, E_ν the neutrino energy and
        𝒬^V_W the vector weak charge written in the form
        
        
            𝒬^V_W =  [ g_V^p Z F_p(Q^2) +  g_V^n N F_n(Q^2) ]    .
        
        Here, Z and N are the number of protons and neutrons in the
        nucleus while the neutral current vector couplings, g_V^p,n, are
        given by 
        
        
            g_V^p   =   1/2-2 sin^2 θ_W   ,
            
             
            g_V^n   =   -1/2  ,
        
        with the weak mixing angle taken in the MS scheme, i.e.  sin^2 θ_W ≡ŝ^2_Z = 0.2312. 
        
        Finally, F_p,n(Q)^2 stands for the nuclear form factors for protons and neutrons respectively, for which we employ the well-known Helm parametrization
        
        
            F_p,n(Q^2) = 3j_1(QR_0)/QR_0exp(-Q^2s^2/2) ,
        
        where the magnitude of the three-momentum transfer is Q=√(2m_AT_A), j_1 denotes the spherical Bessel function of order one and
        R_0^2=5/3(R_p,n^2-3s^2) with R_n=3.36 fm (R_p=3.14 fm) denoting the neutron (proton) rms radius and s=0.9 fm.
        
        
        To analyze the recent results of the liquid Argon detector reported by
        the COHERENT collaboration, we will consider in this work a neutrino
        flux arriving to the detector from the SNS at ORNL,  given by three different components from the
        π^+ decay at rest. These are a “prompt” monoenergetic muon
        neutrino signal given by
        
        
            dN_ν _μ/dE_ν=ηδ ( E_ν-m_π^2-m_μ^2/2m_π )   ,
        
        and the “delayed” neutrino flux composed of muon antineutrinos
        
        
            dN_ν _μ/dE_ν= η64E_ν^2/m_μ^3 ( 3/4-E_ν/m_μ )   ,
        
        and electron neutrinos
        
        
            dN_ν _e /dE_ν= η192E_ν^2/m_μ^3 ( 1/2-E_ν/m_μ )   ,
        
        with the normalization factor η given by η = rN_POT/4π L^2. The number of protons on target (POT) corresponding to the 6.12 GWh exposure is  N_POT= 1.37×10^23,  r=0.08 denotes the produced neutrinos per POT and L=27.5 m is the CENNS-10 baseline.
        
        In the present work, prompted by the importance of the liquid Argon detector of the COHERENT
        collaboration, we study  relevant implications of
        the measurement for different standard and new physics scenarios. 
        
        
        
        § THE ANALYSIS
        
        As a first step, we simulate the CEvNS signal at the LAr detector using the efficiency function [Taken from Fig. 3 of Ref. <cit.>.]𝒜(T_A), corresponding to the “Analysis A”  of Ref. <cit.>. We then convert the nuclear recoil spectrum into  electron recoil space through the reported quenching factor QF(T_A). Following Ref. <cit.>, we evaluate the number of events in the region of interest, i.e. for recoil energies below 120 keV_nr≈ 30 keV_ee. Our simulated energy spectrum is shown in Fig. <ref> as a function of the electron recoil energy,  T_er. 
        
        
        
        
        Given the reliability of our simulated CENNS-10 signal, we perform  a statistical analysis of the recent liquid Argon
        CEvNS measurement with the ultimate goal of probing important observables such as the neutron mean radius, the  electroweak mixing angle sin^2θ_W,
        as well as to constrain new physics parameters. Before displaying our results in the next sections, here we
        discuss the general procedure we followed to investigate the different scenarios. 
        
        To test the sensitivity of the experiment to  observables under study, we
        have performed a χ^2 analysis, minimizing the function:
        
        
            χ^2 (X) =  αmin [ (N_meas - N_theor(X) [1+ α]  )^2/σ_stat^2 
              + (α/σ_α)^2   ]   ,
        
        with N_meas=159 denoting the number of the measured events from the fit of “Analysis A” in Ref. <cit.> and
        N_theor(X) being the theoretical prediction. Here, the argument X represents
        the set of parameters to be tested, such as the weak mixing angle, the neutron rms radius or NSI parameters.
        
        Here we note that we have successfuly calibrated our procedure with the one discussed in the recent CENNS-10 result.
        
        In Eq.(<ref>), the statistical uncertainty is given by
           σ_stat=√(N_meas+ N_BRN), where
        N_BRN=563 represents the number of background events due to beam related neutrons (BRN).
        The parameter α quantifies the normalization, that has a
        systematic error σ_α =8.5% (for details, see Ref. <cit.>).
        
        
        
         §.§ Standard electroweak and nuclear physics
        
        
        One of the most important parameters of the SM is the weak mixing angle, that is measured with great accuracy at the Z peak. At low energies, however, the existing measurements are less precise but still very relevant given the prediction of an increase of about 3% in its value due to radiative corrections. Moreover, any deviation from 
        the SM prediction for this value would be a signature of new physics. 
        
        With this motivation in mind, we have performed a χ^2 analysis for this SM parameter using the liquid Argon data.
        
        Our corresponding results are shown in the left panel of Fig. <ref>, where one can see a notable improvement with respect to the previous determination of sin^2 θ_W
        from the COHERENT-CsI data (see Ref. <cit.>). The new measurement of the weak mixing angle, derived from the CENNS-10 data at 90% C.L. reads
        
        
            sin^2 θ_W = 0.258^+0.048_-0.050
        
        
        Another very useful standard information that can be obtained from the CEvNS interaction is the neutron mean radius R_n for the Argon isotope.
        
        Although there are theoretical predictions for this value, its direct determination can facilitate a better understanding of the CEvNS background at dark matter oriented experiments <cit.>.
        
        We have performed the corresponding analysis for this observable and the obtained result is illustrated in the right panel of Fig. <ref>. Although not directly comparable, the average neutron rms radius of CsI is also shown for the reader's convenience. On the other hand, it is worthwhile to notice that  R_n is more severely constrained for the case of Argon. The obtained 90% C.L. limit for the neutron rms radius for Argon reads
        
        
            R_n < 4.33  fm  .
        
        We should note that this provides the first experimental determination of the neutron radius in Argon. In addition, comparing with the previous result on CsI <cit.> (see also Refs. <cit.>), one sees that the level of precision seems somewhat improved. 
        
        
        
        
         §.§ Non-standard Interactions
        
        
        Most models that try to explain the neutrino mass pattern predict a modification of the V-A couplings predicted by the SM. In many cases,
        the corrections are expected to be negligible, like in the most simple type I seesaw model while, in other cases, there could be a relatively
        larger signal, as for the linear and inverse seesaw cases. A large family of new physics models can be phenomenologically described  using
        the formalism of NSI, that modify the neutral current SM Lagrangian through the contribution <cit.>
        
            L^NSI_NC=-2√(2)G_F ∑_f,P,α,βε_αβ^f P(ν̅_αγ^μ P_Lν_β)(f̅γ_μ P_X f)   ,
        
        where f corresponds to an elementary fermion that, in the case of CEvNS, reduces to the quarks of the first family,
          f={u,d}. α and β denote the neutrino flavors {e,  μ, τ}, P_X the left and right chirality projectors
          P_L,R, and ε_αβ^f P are the couplings that quantify the relative strength of the NSI.
        
        Due to the presence of these new interactions, the weak charge of the CEvNS reaction is modified according to the substitution
        𝒬^V_W →𝒬^V_NSI in Eq. (<ref>), with the NSI charge given by
        
        
            𝒬^V_NSI   =    [  ( g_V^p+2ε _αα^uV+ε _αα^dV )Z F_p(Q^2)+ ( g_V^n+ε _αα^uV+2ε _αα^dV ) N  F_n(Q^2) ]  
            
                 +   ∑_α [  ( 2ε _αβ^uV+ε _αβ^dV ) Z F_p(Q^2)+  ( ε _αβ^uV+2ε _αβ^dV )N F_n(Q^2)     ] .
        
        As it has already been noticed <cit.>, CEvNS reaction is sensitive to the NSI parameters and, therefore, it can provide
        important information to probe the so-called LMA-Dark solution <cit.>. The results of our χ^2 analysis, for one
        NSI parameter at a time, are shown in Fig. <ref>, both for the flavor changing (left panel) and the non-universal case (right panel).
        
        We can see from this figure that the sensitivities on the flavor changing NSI parameters are only marginally improved with respect to the previous CsI
          case. This is due to the detection of a larger number of events with respect to the SM prediction. Although the excess is below one standard deviation, still
          the preferred value for the flavor changing parameters are non-zero, as can be seen in Fig. <ref>. In the case of non-universal NSI, one can see the improvement in their restriction
        in comparison with the first CEvNS detection. 
        
        
         We can go one step further in the analysis and study more general restrictions on NSI parameters <cit.>.
          
          For example, the new CENNS-10 measurement can be used to constrain pairs of NSI parameters, allowing us to seek for possible correlations between them, as shown in Fig. <ref>,
          where the constraints on the two-dimensional parameter space of non-universal and flavor-changing NSI couplings with d quark (ε_ee^dV, ε_τ e^dV) are given (left panel),
          as well as those for the case of the non-universal NSI couplings with d and u quarks (ε_ee^dV, ε_ee^uV). In both cases one can appreciate the improvement in the determination of the parameters. The good consistency of our analysis with the available results of Ref. <cit.> is evident from the right panel of this figure.
         
        
        
        
         §.§ Electromagnetic properties
        
        
        The discovery of neutrino oscillations with solar, atmospheric, reactor  and accelerator neutrinos <cit.> has set a new milestone in particle physics pointing to the existence of massive neutrinos, hence constituting the clearest signature of new physics beyond the SM. The non-vanishing neutrino mass stands out as the best motivation for non-trivial electromagnetic (EM) neutrino properties. Indeed, the expansion of the EM neutrino vertex (for details see Ref. <cit.>) yields two main phenomenological parameters, namely the neutrino magnetic moment and the neutrino charge radius <cit.>. 
        
        
        
        
        
        The neutrino magnetic moment μ_ν_α with α= e, μ, τ is a flavor-dependent quantity  which, for the case of scattering experiments, is usually expressed in the mass basis <cit.>.  Due to the helicity-violating nature of the EM cross section, there is no interference with the SM one given in Eq.(<ref>) and yields an additive contribution of the form
        
        
            ( d σ/dT_A)_EM=π a^2_EMμ_ν^2 Z^2/m_e^2(1-T_A/E_ν/T_A) F_p^2(Q^2) ,
        
        where the flavor index has been dropped. For sufficient low detection threshold, the latter cross section leads to an enhancement of the recoil spectrum, i.e. a feature that is not expected for the other types of new physics considered in this work. Note that, for the case of Majorana neutrinos, only transition magnetic moments are expected, and the corresponding sensitivities from the analysis of neutrino-electron scattering <cit.> and CEvNS <cit.> experiments have already been given in the literature. Here, for simplicity, we only consider flavor-dependent effective neutrino magnetic moments. The resulted sensitivity profiles relevant to μ_ν_e, μ_ν_μ and μ_ν̅_μ from the analysis of the recent CENNS-10 data are shown in the left panel of Fig. <ref>. The obtained constraints at 90% C.L. read 
        
        
            ( μ_ν_e, μ_ν_μ, μ_ν̅_μ) < (94, 53, 78) 10^-10μ_B  .
        
        We notice that the LAr sensitivity on the effective neutrino magnetic moment is not drastically improved in comparison to the one reached with the first COHERENT-CsI data <cit.>.
        
          This is due to the fact that the CENNS-10 result of N_meas= 159 events is by about 30 events larger than the 130 events expected in the Standard Model.
          
          Therefore, even though the systematic uncertainties of CENNS-10 experiment are better compared to the first CsI measurement, these extra 30 events in the χ^2 translate into a finite neutrino magnetic moment contribution, thus weakening the limits.
        
        
        
        
        
        We now turn our attention to the neutrino charge radius ⟨ r_ν_α^2⟩ with α= e, μ, τ being the flavor index. Likewise the neutrino magnetic moment, ⟨ r_ν_α^2⟩ is also required to be expressed in the mass basis through a rotation with the lepton mixing matrix <cit.>. Being a helicity-preserving quantity, its impact to the SM cross section is simply taken as a shift on the weak mixing angle according to 
        
        
            sin^2 θ_W →ŝ^2_Z + √(2)πα_EM/3 G_F⟨ r_ν_α^2⟩  .
        
        Note that only the proton coupling g_V^p, proportional to the number of protons, interacts with the charge radius[We neglect the contribution of the term proportional to Z^2 corresponding to transition charge radii <cit.>.]. On the other hand, when antineutrinos are involved, both the g_V^p and ⟨ r_ν_α^2⟩ change sign and, therefore, Eq.(<ref>) holds for both neutrinos and antineutrinos, a result that is consistent with Ref. <cit.>. From our analysis of the recent CENNS-10 data, we obtain the sensitivity to the neutrino charge radii corresponding to ⟨ r_ν_e^2⟩, ⟨ r_ν_μ^2⟩ and ⟨ r_ν̅_μ^2⟩, as shown in the right panel of Fig. <ref>. The extracted constraints at 90% C.L. read 
        
        
            ⟨ r_ν_e^2⟩ =    (-64, -41)   and   (-7, 16)  , 
            ⟨ r_ν_μ^2⟩ =    (-69, -37)   and   (-10, 21)  , 
            ⟨ r_ν̅_μ^2⟩ =    (-60,-43)  and   (-5, 12)  ,
        
        in units of 10^-32cm^2. Note that, comparing with the corresponding results extracted from the CsI case, the precision of the new determinations derived
        from the new LAr measurement are significantly improved since now the allowed regions are narrower, and appear as two separate intervals.
        
        
        At this point, and as we did for the NSI case, we have performed a combined analysis 
        allowing for several parameters being non-zero at a time. In particular, we have chosen to probe the 
        parameter space of neutrino magnetic moments (μ_ν_α, μ_ν_β) and neutrino charge radii (⟨ r^2_ν_α⟩, ⟨ r^2_ν_β⟩), by considering the simultaneous presence of two of them, i.e. α≠β.
        The corresponding results are presented in Fig. <ref>, where we also compare with those derived from the 2017 data release of the COHERENT-CsI measurement. The  improvement obtained with the most recent data is more than evident.
        
        
        
        
         §.§ Light Mediators
        
        
        It has been recently shown <cit.> that low energy scattering experiments are favorable facilities for probing the existence of light mediators, of both vector <cit.> and scalar <cit.> type. Indeed, by focusing on the Z^' predicted within the context of string-inspired E_6 and Left-Right symmetries, the authors of Ref. <cit.> explored the potential of low-energy measurements at CEvNS experiments, concluding that complimentary information to high-energy collider searches can be achieved.  
        
        Here, we focus on simplified  U(1)^' scenarios with an additional vector Z^' or a scalar ϕ boson that arise from the generic Lagrangians <cit.>
        
            L_vector =      Z^'_μ(g_Z^'^qVq̅γ^μ q + g_Z^'^ν Vν̅_L γ^μν_L)   , 
             L_scalar =    ϕ(g_ϕ^q Sq̅ q + g_ϕ^ν Sν̅_R ν_L + H.c.)   ,
        
        with M_Z^' and M_ϕ being the mass of the vector and scalar mediators, whereas g_Z^'^fV and g_ϕ^f S are the respective vector and scalar couplings to the fermion f=u,d,ν. For the case of a Z^' mediator, there is an interference with the SM vector couplings, and the corrections to the SM cross section are incorporated through the substitution 𝒬_W^V →𝒬_V^Z^', i.e. replacing the SM weak charge with the Z^' one in Eq.(<ref>), as <cit.>
        
            𝒬_V^Z^' = 
            𝒬_W^V + g_Z^'^ν V/√(2)G_F(2 g^uV_Z^' + g^dV_Z^')Z F_p(Q^2) +  (g^uV_Z^' + 2g^dV_Z^') N F_n (Q^2)/2 m_A T_A + M_Z^'^2  .
        
        
        Turning to the case of a scalar boson mediating the CEvNS process, there is no interference and, then, the total cross section is given by (d σ/dT_A)_tot= (dσ/dT_A)_SM + (d σ/dT_A)_scalar, where the scalar contribution to the cross section is expressed as
        
        
            (d σ/d T_A)_scalar = G_F^2 m_A^2/ 4 πg_ϕ^ν S𝒬_ϕ^2    T_A /E_ν^2 ( 2 m_A T_A + M_ϕ^2 )^2  ,
        
        and the scalar charge is defined as <cit.>
        
            𝒬_ϕ=Z F_p (Q^2)∑_q=u,dg_ϕ^qSm_p/m_qf_T_q^p
                   +
                   N F_n (Q^2)∑_q=u,dg_ϕ^qSm_n/m_qf_T_q^n   .
        
        In the latter expression, the scalar charge is expressed in terms of the hadronic form factors f_T_q^q, obtained from chiral perturbation theory (see Ref. <cit.>),
        although here we use the updated values from <cit.>
        
            f_T_u^p   =(20.8± 1.5)× 10^-3 ,    
              f_T_d^p=(41.1± 2.8)× 10^-3 ,
              
            
              f_T_u^n   =(18.9± 1.4)× 10^-3 ,    
              f_T_d^n=(45.1± 2.7)× 10^-3 .
        
        
        At this point, we should note that, for simplicity, we consider
          universal quark couplings for both vector and scalar cases,
          i.e. g_Z^'^uV=g_Z^'^dV and
          g_ϕ^uS=g_ϕ^dS. Therefore, our sensitivity analysis will
          refer to the corresponding squared couplings entering in
          Eqs. (<ref>) and (<ref>) from the product
          of neutrino and quark couplings,
          i.e. g_Z^'^2=g_Z^'^qVg_Z^'^ν V and
          g_ϕ^2=g_ϕ^qSg_ϕ^ν S. Here, we find it interesting to focus on the U(1)_B-L extension of the  where g_Z^'^qV= -g_Z^'^ν V/3 <cit.>. Using the latest data
          from the CENNS-10 measurement, we performed a combined analysis by
          varying simultaneously the vector (scalar) coupling and the
          corresponding vector (scalar) mediator mass. The corresponding excluded
          regions are illustrated in Fig. <ref> and compared with the COHERENT-CsI case. For the vector mediator scenario, our results are also compared with existing limits placed by 
        dielectron resonances at ATLAS <cit.>, constraints from electron beam-dump fixed target experiments <cit.> as well as with
        constraints from Dark Photon searches at BaBar <cit.> and LHCb <cit.>. One sees that CEvNS searches are clearly complementary to the latter ones, excluding a large part of the available parameter space. Notice the slight improvement found with respect to the first COHERENT-CsI measurement.
        
        
        
         §.§ Robustness of the constraints
        
        
        Nuclear physics uncertainties place important limitations on the attainable sensitivities to physics observables extracted from coherent neutrino elastic scattering experiments.
        
          Indeed, as emphasized in Refs. <cit.>, these may lead to a miss-interpretation of the relevant constraints derived from CEvNS measurements.
        
        
        Therefore, before closing our present analysis, we find it useful to devote a separate paragraph in order to discuss the robustness of the constraints we have obtained with regards to the nuclear form factor. To this purpose, we performed a combined analysis of the weak mixing angle and the  neutron rms radius  simultaneously; we also performed a similar analysis for the case of a NSI parameter characterizing new physics. 
        
        While many such combinations are possible, as a concrete example in Fig. <ref> we show the allowed regions in the
          (sin^2 θ_W, R_n) and (ϵ_ee^dV, R_n) planes at 90% C.L.
        
        As expected, in the left panel, one sees how the 90% C.L. determination of the weak mixing angle has a larger relative error for free R_n, in comparison to that of Eq.(<ref>) obtained with the fixed value R_n=3.36 fm. We find δ s^2_W (free R_n)=0.128 vs. δ s^2_W(fixed R_n)=0.097, where δ s_W^2  corresponds to the width of the 90% C.L. band.
        
        On the other hand, concerning new physics, we show in the right panel the allowed region on the NSI parameter ε_ee^dV for different values of the neutron rms radius R_n.
        
        One sees that, by using a free rms neutron radius R_n, the 90% C.L. leads to two disjoint ranges (for R_n>2.7 fm) and a reduced sensitivity compared to the results obtained from the analysis with a fixed rms radius shown in Fig. <ref>.  
        
        In both cases, it becomes evident that the limitations imposed due to the nuclear physics uncertainties must be treated with special care. In fact, this may require realistic nuclear structure calculations <cit.>.
        
        
        
        § CONCLUSIONS
        
        
        We have analyzed the recent results of the CENNS-10 detector subsystem of the COHERENT collaboration that led to the first detection of CEvNS on LAr.
        
        Through a dedicated statistical analysis, taking into account the available information from Ref. <cit.>, we have shown that this new measurement typically leads
        to improved sensitivities with respect to the first COHERENT-CsI measurement in 2017.
        
        Specifically, we have presented an improved determination of the weak mixing angle, as well as the first ever determination of the ^40Ar neutron rms radius.
        
        Turning to new physics,  we have derived the constraints on non-universal as well as flavor-changing NSI imposed by this new data release.
        
        Moreover, concerning neutrino electromagnetic properties, we have found only minor improvement of the sensitivity to neutrino magnetic moments.
        In contrast, we have found a positive indication for finite neutrino-charge radii.
        
        We have shown that the new CENNS-10 data provides somewhat better sensitivities on simplified scenarios involving new light mediators when compared to COHERENT-CsI data,
          discussing also the complementarity to high energy experiments.
        
        Finally, we have explored the impact of nuclear physics uncertainties and discussed the robustness of our results.
        
        
        The authors acknowledge Carlo Giunti for useful comments.
        This work is supported by the Spanish grants FPA2017-85216-P
        (AEI/FEDER, UE), PROMETEO/2018/165 (Generalitat Valenciana) and the Spanish Red Consolider MultiDark FPA2017-90566-REDC, and by
        CONACYT-Mexico under grant A1-S-23238. OGM has been supported by SNI (Sistema Nacional de Investigadores). The work of DKP is co-financed by Greece and the European Union (European Social Fund- ESF) through the Operational Programme <<Human Resources Development, Education and Lifelong Learning>> in the context of the project “Reinforcement of Postdoctoral Researchers - 2nd Cycle" (MIS-5033021), implemented by the State Scholarships Foundation (IKY). MT acknowledges financial
        support from MINECO through the Ramón y Cajal contract
        RYC-2013-12438.
        
        
        utphys
