Radiative corrections to low-energy neutrino reactions

We show that the radiative corrections to charged current (CC) nuclear reactions with an electron (positron) in the final state are described by a universal function. The consistency of our treatment of the radiative corrections with the procedure used to extract the value of the axial coupling constant g(A) is discussed. To illustrate we apply our results to (anti) neutrino deuterium disintegration and to pp fusion in the sun. The limit of vanishing electron mass is considered, and a simple formula sufficiently accurate for E(obs)greater than or similar to 1 MeV is obtained. The size of the nuclear structure-dependent effects is also discussed. Finally, we consider CC transitions with an electron (positron) in the initial state and discuss some applications to electron capture reactions.