Propagation of Majorana fermions in hot plasma

The properties of Majorana fermions in hot plasma are studied. One-loop resummed propagator, dispersion relations and their interpretation are discussed. It is shown that particle and hole-like solutions appear as in Dirac/chiral fermion case. The dispersion relations are, however, crucially different. We find that, in the presence of a large zero temperature bare mass, hole-like excitations possess a negligible effective mass. As an example of a real application, we consider the neutralinos in the minimal supersymmetric extension of the standard model and argue that for realistic values of the soft supersymmetry breaking masses the existence of practically massless hole-like excitations has a considerable effect on the thermal properties, e.g. the thermalization rate, of particles interacting with these Majorana excitations.