Nuclear response theory for isospin transfer in relativistic framework

Nuclear response theory for isospin transfer modes has numerous applications extending across the field of nuclear physics from beta decay, neutrino scattering, electron capture, two-neutrino and neutrino-less double beta decay to weak processes in stars. Precise information on such modes of excitation as Gamow-Teller resonance and spin-dipole resonance is needed to compute weak reaction rates, which are important for astrophysical modeling. In this work we present a theoretical approach to nuclear spin-isospin response. It is based on the relativistic Lagrangian and includes explicitly effective meson degrees of freedom to describe nucleon-nucleon interaction, and, at the same time, emergent collective phenomena which can be quantified consistently as an additional nucleon-nucleon interaction induced by the nuclear medium. Pion-nucleon interaction is considered with the free-space coupling constant [1,2]. The recent development introduces pairing correlations of the superfluid type, which are needed for a correct description of open-shell nuclei [3]. New results of calculations for Gamow-Teller resonance and for spin-dipole resonance in medium-mass nuclei will be presented and discussed. \\[4pt] [1] T. Marketin, E. Litvinova, D. Vretenar, P. Ring, Phys. Lett. B 706, 477 (2012).\\[0pt] [2] E. Litvinova, B.A. Brown, D.-L. Fang, T. Marketin, R. G. T. Zegers, Phys. Lett. B 730, 307 (2014).\\[0pt] [3] C. Robin, E. Litvinova, to be published.