T approximation in the theory of a normal Fermi liquid

The characteristics determining the spectrum of Fermi systems are calculated in the framework of the statistical T approximation. It is shown that the effective mass can be estimated with greater accuracy than the energy gap. It is shown that it may be important to take into account corrections in the calculation of the microscopic characteristics at T=0 in the framework of the eikonal T approximation.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 32–37, August, 1977.