Effective potential of the O(N) linear sigma-model at finite temperature |
| |
Authors: | Y Nemoto K Naito M Oka |
| |
Institution: | (1) Department of Physics, Tokyo Institute of Technology Meguro, Tokyo 152-8551 Japan, JP;(2) Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502 Japan, JP;(3) Radiation Laboratory, the Institute of Physical and Chemical Research (RIKEN) Wako, Saitama 351-0198 Japan, JP |
| |
Abstract: | We study the O(N) symmetric linear sigma-model at finite temperature as the low-energy effective models of quantum chromodynamics (QCD) using
the Cornwall-Jackiw-Tomboulis (CJT) effective action for composite operators. It has so far been claimed that the Nambu-Goldstone
theorem is not satisfied at finite temperature in this framework unless the large-N limit in the O(N) symmetry is taken. We show that this is not the case. The pion is always massless below the critical temperature, if one
determines the propagator within the form such that the symmetry of the system is conserved, and defines the pion mass as
the curvature of the effective potential. We use a regularization for the CJT effective potential in the Hartree approximation,
which is analogous to the renormalization of auxiliary fields. A numerical study of the Schwinger-Dyson equation and the gap
equation is carried out including the thermal and quantum loops. We point out a problem in the derivation of the sigma meson
mass without quantum correction at finite temperature. A problem about the order of the phase transition in this approach
is also discussed.
Received: 21 June 2000 / Accepted: 13 September 2000 |
| |
Keywords: | PACS 11 30 Rd Chiral symmetries – 11 10 Wx Finite-temperature field theory – 12 39 Fe Chiral Lagrangians |
本文献已被 SpringerLink 等数据库收录! |
|