Ultra-high energy neutrino dispersion in plasma and radiative transition ν_L to ν_R + γ

Qualitative analysis of additional energy of neutrino and antineutrino in plasma is performed. A general expression for the neutrino self-energy operator is obtained in the case of ultra-high energies when the local limit of the weak interaction is not valid. The neutrino and antineutrino additional energy in plasma is calculated using the dependence of the $W$ and $Z$--boson propagators on the momentum transferred. The kinematical region for the neutrino radiative transition (the so-called "neutrino spin light") is established for some important astrophysical cases. For high energy neutrino and antineutrino, dominating transition channels in plasma, $\nu_e + e^+ \to W^+$, $\bar\nu_e + e^- \to W^-$ and $\bar\nu_{\ell} + \nu_{\ell} \to Z$, are indicated.