Summation of infrared singularities of the electron propagator at finite temperature

The paper on the summation of infrared singularities of the electron propagator is a contribution to the book commemorating the sixtieth birthday of E.S. Fradkin. In the paper, the QED field-theoretical expression for the Green function of an electron in the infrared region is extended to the case of quantum statistical physics. The expression is analysed for the Green function obtained within the lowest order of the modified perturbation theory, and the infrared divergences effectively summed in it are discussed. (U.K.)