Advances in neutrino transport allow realistic neutrino interactions to be incorporated into supernova simulations. We add tensor couplings to relativistic random phase approximation calculations of neutrino opacities. Our results reproduce free-space neutrino-nucleon cross sections at low density, including weak magnetism and recoil corrections. In addition, our opacities are thermodynamically consistent with relativistic mean field equations of state. We find antineutrino mean free paths that are considerably larger then those for neutrinos. This difference depends little on density. In a supernova, this difference could lead to an average energy of ${\overline{\nu }}_{\mu }$ that is larger than that for ${\nu }_{\mu }$ by an amount that is comparable to the energy difference between ${\nu }_{\mu }$ and ${\overline{\nu }}_e.$

• Received 11 May 2003

DOI:https://doi.org/10.1103/PhysRevC.68.025803