Neutrino quantum states in matter
  We propose a modified Dirac equation for a massive neutrino moving in the presence of the background matter. The effects of the charged and neutral-current interactions with the matter as well as the matter motion and polarization are accounted for. In the particular case of the matter with a constant density the exact solutions of this equation are found, the neutrino energy spectrum in the matter is also determined. On this basis the effects of the neutrino trapping and reflection, the neutrino-antineutrino pair annihilation and creation in a medium are studied. The quantum theory of the spin light of neutrino in matter ($SL\nu$) is also developed. 
Alexander Studenikin and Alexei Ternov