in astronomy the brightest star in a constellation Iron ferrite and numerous phases within materials science the return in excess of the compensation for the risk borne in investment the α-conversion in lambda calculus the independence number of a graph a placeholder for ordinal numbers in mathematical logic a type of receptor for the neurotransmitter noradrenaline in neuroscience Ββ (beta) Β represents the beta function represents: the thermodynamic beta, equal to (kBT)−1, where kB is Boltzmann's constant and T is the absolute temperature. the second angle in a triangle, opposite the side b the standardized regression coefficient for predictor or independent variables in linear regression (unstandardized regression coefficients are represented with the lower-case Latin b, but are often called "betas" as well) the ratio of collector current to base current in a bipolar junction transistor (BJT) in electronics (current gain) the false negative rate in statistics ("Type II" error) the beta coefficient, the non-diversifiable risk, of an asset in mathematical finance the sideslip angle of an airplane a beta particle (e− or e+) the beta brain wave in brain or cognitive sciences ecliptic latitude in astronomy the ratio of plasma pressure to magnetic pressure in plasma physics β-reduction in lambda calculus the ratio of the velocity of an object to the speed of light as used in the Lorentz factor a type of receptor for the noradrenaline neurotransmitter in neuroscience Γγ (gamma) Γ represents: the circulation in fluid dynamics the reflection coefficient of a transmission or telecommunication line. the confinement factor of an optical mode in a waveguide the gamma function, a generalization of the factorial the upper incomplete gamma function the modular group, the group of fractional linear transformations the gamma distribution, a continuous probability distribution defined using the gamma function second-order sensitivity to price in mathematical finance the Christoffel symbols of the second kind the stack alphabet in the formal definition of a pushdown automaton , or the tape-alphabet in the formal definition of a Turing machine the Feferman–Schütte ordinal Γ0 represents: the specific weight of substances the lower incomplete gamma function the third angle in a triangle, opposite the side c the Euler–Mascheroni constant in mathematics gamma rays and the photon the heat capacity ratio in thermodynamics the Lorentz factor in special relativity Δδ (delta) Δ represents: a finite difference a difference operator a symmetric difference the Laplace operator giving heat in a chemical reaction the angle