Optimized perturbation theory at finite temperature: Renormalization and Nambu-Goldstone theorem in O(N) phi**4 theory

Aug, 1998

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Abstract:
The optimized perturbation theory (OPT) at finite temperature recently developed by the present authors is reviewed by using O(N) phi^4 theory with spontaneous symmetry breaking. The method resums automatically higher loops (including the hard thermal loops) at high TT and simultaneously cures the problem of tachyonic poles at relatively low TT. We prove that (i) the renormalization of the ultra-violet divergences can be carried out systematically in any given order of OPT, and (ii) the Nambu-Goldstone theorem is satisfied for arbitrary NN and for any given order of OPT.
Note:
  • Talk given at ``Thermal Field Theories and Their Applications'', (Regensburg, Germany, August, 10-14, 1998). RevTeX 10 pages, with 9 eps figures
  • talk: Regensburg 1998/08/10
  • perturbation theory: higher-order
  • finite temperature
  • phi**n model: 4
  • symmetry: O(N)
  • expansion 1/N
  • spontaneous symmetry breaking
  • tachyon
  • renormalization
  • Goldstone theorem