Nuclear many-body effects on neutrino absorption in core-collapse supernovae*

The simulation of core-collapse supernovae requires accurate modeling of neutrino opacities, determined by absorption and scattering cross sections. These cross sections are sensitive to nuclear collective excitations and many-body correlations. In this work, we present a study of many-body effects through the random phase approximation (RPA) using the model-independent low-momentum nucleon–nucleon interaction, $V_{\text{low }k}$. We find that the RPA correlations shift the response function to higher energy transfers and suppress the neutrino absorption cross section. We also observe a strong resolution scale dependence in the cross section, with coarser resolution scales yielding larger neutrino absorption rates. Our results highlight the importance of nuclear many-body effects and the choice of internucleon potential for computing neutrino absorption in core-collapse supernova simulations.