Dependence of cross sections of electroweak processes on the temperature of the Universe

The behavior of amplitudes and cross section of themain processes, caused by electromagnetic and weakinteractions of particles during the contraction ofthe Standard Model gauge group is analysed. Thedependences of the elastic scattering cross sectionsof photons, electrons (positrons) and neutrinos (antineutrinos) on electrons, as well as the annihilationof electrons and positrons into two photons, into aneutrino-antineutrino pair, into a muon-antimuonpair on the temperature of the Universe are established, taking into account that the contraction parameter is inversely proportional to the temperatureε~T-1.