Chiral nuclear axial currents and selected applications to few-nucleon systems

Nuclear chiral effective field theory (xEFT) is the theoretical framework that permits the derivation of nuclear potentials and electroweak currents from the symmetries of QCD|the exact Lorentz, parity and time-reversal symmetries, and the approximate chiral symmetry. In this talk, the derivation of the one- and two-nucleon axial charge and current operators in xEFT will be sketched. The resulting axial current is found to be finite and conserved in the chiral limit, while the axial charge requires renormalization. The unknown low energy
constant entering in the axial current has been fitted to reproduce the experimental value of the Gamow-Teller matrix element in tritium B decay. Lastly the calculation of the neutrino-deuteron inclusive cross sections at low energies will be discussed. In particular, these results have confirmed previous predictions obtained in phenomenological approaches, which have played an important role for the interpretation of the experiment at the Sudbury Neutrino
Observatory.