Energy exchange in neutrino nuclear scattering

Neutrino nuclear scattering in hot and dense matter relevant for supernovae, neutron star mergers, and proto-neutron stars is considered. At finite temperature, neutrinos exhibit exo- and endoenergetic scattering on nuclear species due to the neutral-current Gamow-Teller interaction component. From an analysis of energy transfer and straggling cross sections we demonstrate that additional noticeable mechanisms in equilibrating neutrinos with matter originate in magnetized nucleon gas. Average energy transfer, i.e., ratio of energy transfer and scattering cross sections, depends almost linearly on neutrino energy and changes from positive to negative value. For hot nuclear material such crossover between acceleration and stopping regimes occurs when neutrino energy is about a factor four of temperature. Similar features are displayed for neutrino scattering on hot atomic nuclei. For the Fe56 nucleus the stopping regime starts at energies slightly above than four times temperature. Possible effects in neutrino transport and spectra are discussed.