Nuclear transitions of astrophysical interest in the relativistic nucleon-vibration coupling framework

Abstract:  The response of nuclei to external probes has many applications across the field of astrophysics. A precise description of neutral and charge-exchange excitations is necessary to compute the rates of various processes such as neutron-capture, 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 the nuclear response. This method describes the nucleus as a system of relativistic protons and neutrons interacting via effective meson exchange, and builds inter-nucleon correlations by accounting for the coupling between single nucleons and collective vibrations of the nucleus. Such correlations typically induce fragmentation and spreading of the transition strength which are essential for a precise description of giant resonances and low-energy modes, and have a great impact on the computing of decay and reaction rates. I will present calculations of various excitation modes and corresponding astrophysical rates in mid-mass and heavy nuclei. Emphasis will be put on recent calculations of Gamow-Teller transitions for beta-decay and electron-capture rates.