On Fermion-Graviton Scattering at Finite Temperature

The early universe is dominated by phenomena at high temperatures. The thermal effects decrease during evolution of the universe. However there are some phenomena, such as processes inside stars and black holes, where the role of the temperature is important. Study of processes involving gravitons at finite temperature is a viable means to understand gravitational processes in the universe. Using the Thermo Field Dynamics formalism transition amplitudes involving gravitons and fermions at finite temperature are calculated. In this approach our results consist of two parts: one corresponding to the zero temperature part and the other corresponding to a temperature dependent part.