Four-loop screened perturbation theory

2008/05/31 by Jens O. Andersen, Lars Kyllingstad · 1 citation
Physics and Astronomy · #hep-ph

paper · pdf · doi:10.1103/physrevd.78.076008

published as Phys.Rev.D78:076008,2008 · 34 pages, 6 figures, RevTeX

arxiv created 2008/10/27 · arxiv updated 2009/12/01

Abstract

We study the thermodynamics of massless phi-fourth theory using screened perturbation theory. In this method, the perturbative expansion is reorganized by adding and subtracting a thermal mass term in the Lagrangian. We calculate the free energy through four loops expanding in a double power expansion in m/T and g², where m is the thermal mass and g is the coupling constant. The expansion is truncated at order g⁷ and the loop expansion is shown to have better convergence properties than the weak-coupling expansion. The free energy at order g⁶ involves the four-loop triangle sum-integral evaluated by Gynther, Laine, Schroeder, Torrero, and Vuorinen using methods developed by Arnold and Zhai. The evaluation of the free energy at order g⁷ requires the evaluation of a nontrivial three-loop sum-integral, which we calculate by the same methods.

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• SIRENA -- Sum-Integral REductioN Algorithm

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