Neutrinos in extremely strong magnetic fields

We compute the dispersion curves for neutrinos propagating in a very dense electroweak plasma, in magnetic fields of order B less than or equal to M-W (2)/e. The neutrino self-energy is calculated in the one-loop approximation . The dispersion equation is solved for motion parallel and perpendicular t o the external magnetic field. We obtain an effective neutrino mass which i ncreases with the magnetic field, up to values B where threshold energy for creation of W+/- pairs (out from the thermal background) is reached.