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Title: Higher orders of perturbation theory and summation of series in quantum mechanics and field theory

Journal Article · · Sov. Phys. - JETP (Engl. Transl.); (United States)
OSTI ID:6400457

The Borel method of summation of a perturbation-theory series with factorially increasing coefficients is considered. The connection between the asymptotic form of the coefficients a/sub k/ of this series for k..-->..infinity and the nature of the singularity of the sum is established. An improved perturbation theory is constructed and the limits of its region of applicability are found. The results obtained are verified for a number of physical problems (the Lagrange function in the nonlinear electrodynamics of the vacuum, the energy levels of an electron in the Coulomb field of a nucleus with Z>137, the screening of the nuclear charge by the vacuum shell of a supercritical atom, and the Stark effect in the hydrogen atom) for which the coefficients of the perturbation-theory series increase factorially and for which, at the same time, (analytically or numerically) exact solutions are known. Application of the improved perturbation theory to the gphi/sup 4//4exclamation scalar field theory makes it possible to establish the behavior of the Gell-Mann--Low function psi (g) for 0< or approx. =0.3. In this interval psi (g) is a monotonically increasing function of the coupling constant g.

Research Organization:
Institute of Theoretical and Experimental Physics
OSTI ID:
6400457
Journal Information:
Sov. Phys. - JETP (Engl. Transl.); (United States), Vol. 47:2
Country of Publication:
United States
Language:
English