NEUTRINO SELF-ENERGY AND DISPERSION EQUATION IN DENSE MATTER

Abstract

General expressions for the neutrino self-energy and dispersion equations are found in a medium at finite temperature and density. The neutrino self-energy is calculated in the one-loop approximation and using the unitary gauge. The singularities and the absorption mechanisms are discussed. The low momentum (as compared with the vector boson masses) limit of the self-energy is obtained and from it, the dispersion equations for the quasiparticles are found. These solutions exhibit a group velocity smaller than unity which decreases with increasing density and an energy gap leading to a superfluid-type spectrum. In the particle–antiparticle asymmetric case, a negative effective mass is found for neutrinos.