Universal effective action for O(n)-symmetric λϕ^4 model from renormalization group

Abstract

The RG expansions for renormalized coupling constants g_6 and g_8 of the 3D n-vector model are calculated in the 4-loop and 3-loop approximations respectively. Resummation of the RG series for g_6 by the Pade-Borel-Leroy technique results in the estimates for its universal critical values g_6^*(n) which are argued to deviate from the exact numbers by less than 0.3%. The RG expansion for g_8 demonstrates stronger divergence being much less suitable for getting reliable numerical estimates.

arXiv comment5 pages, LaTeX, no figures, reported at the XI Intern. Conf. "Problems of Quantum Field Theory" (July 13-17, 1998, Dubna, Russia), submitted to the Conference Proceedings