Charge-exchange modes and weak-interaction processes in Relativistic Nuclear Field Theory

Nuclear excitations with isospin transfer play a crucial role in our understanding of nuclear structure, particle physics and astrophysics. A precise description of such transition modes is needed to compute the rates of weak interaction processes such as beta decay, neutrino scattering or electron capture, which are needed for the modeling of nucleosynthesis and stellar evolution. In this talk I will present a theoretical approach to the description of charge-exchange modes in nuclei. This method describes the nucleus as a system of relativistic nucleons interacting via effective meson exchange and applies nuclear field theory to account for inter-nucleon correlations emerging from the coupling between nucleons and collective vibrations. In the charge-exchange channel the particle-vibration coupling generates a time-dependent proton-neutron interaction, in addition to the static pion and rho-meson exchange, which induces fragmentation and spreading of the transition strength. Such dynamical effects are essential for an accurate description of giant resonances and low-energy modes, and have a great impact on the calculation of weak-interaction rates and on the quenching of the Gamow-Teller strength. I will present some applications to Gamow-Teller transitions as well as single- and double-beta decay in nuclei of various masses.