INFRARED AND MASS SINGULARITIES CANCELLATION IN FINITE-TEMPERATURE AND FINITE-DENSITY RADIATIVE-CORRECTIONS TO THE MSW EFFECT

Finite-temperature and -density radiative corrections to order alpha t o the charged-current MSW process are considered in the real-time vers ion of thermal field theory. We confirm the absence of infrared and el ectron mass singularities in the real part of the nu(e) self-energy, c alculated in a background of electrons at finite chemical potential. A s a consequence, this indicates that at order a the perturbation serie s with respect to electromagnetic interactions is adequate for a coher ent process.