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

Sokolov, A. I.; Orlov, E. V.; Ul'kov, V. A.; Kashtanov, S. S.

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

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Description

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.
5 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