Neutrino–nucleus reactions with the relativistic quasiparticle RPA

Abstract

We introduce a novel theoretical framework for the description of weak interaction rates in reactions of leptons with finite nuclei. The weak interaction of leptons with hadrons is expressed in the standard current–current form, the nuclear ground state is described with the relativistic Hartree–Bogoliubov model and the relevant transitions to excited states are calculated in the relativistic quasiparticle random phase approximation. The model is tested for electron– and muon–neutrino reactions on 12C, in a study of cross sections averaged over experimental neutrino fluxes. Using 56Fe as an example, it is shown that at higher neutrino energies the inclusion of spin-dipole transitions, and also excitations of higher multipolarities, is essential for a quantitative description of neutrino–nucleus cross sections.