Plasma induced fermion spin-flip conversion $f_L\to f_R+\gamma$

The fermion spin-flip conversion $f_L\to f_R+\gamma$ is considered, caused by the difference of the additional energies of the electroweak origin, acquired by left- and right-handed fermions (neutrino, electron) in medium. An accurate taking account of the fermion and photon dispersion in medium is shown to be important.