2022-01-27T03:57:28Zhttps://eprints.lib.hokudai.ac.jp/dspace-oai/requestoai:eprints.lib.hokudai.ac.jp:2115/711492019-05-16T04:05:59Zhdl_2115_20066hdl_2115_154Study of hadrons using the Gaussian functional method in theO(4) linear σ modelChen, Hua-XingImai, ShotaroToki, HiroshiGeng, Li-Shenglinear σ modelsigma and pionGaussian functional methodBethe-Salpeter equationNambu-Goldstone theoremfinite temperature420We study properties of hadrons in the O(4) linear σ model, where we take into account fluctuations of mesons around their mean field values using the Gaussian functional (GF) method. In the GF method we calculate dressed σ and π masses, where we include the effect of fluctuations of mesons to find a better ground state wave function than the mean field approximation. Then we solve the Bethe-Salpeter equations and calculate physical σ and π masses. We recover the Nambu-Goldstone theorem for the physical pion mass to be zero in the chiral limit. The σ meson is a strongly correlated meson-meson state, and seems to have a two meson composite structure. We calculate σ and π masses as functions of temperature for both the chiral limit and explicit chiral symmetry breaking case. We get similar behaviors for the physical σ and π masses as the case of the mean field approximation, but the coupling constants are much larger than the values of the case of the mean field approximation.IOP PublishingJournal Articleapplication/pdfhttp://hdl.handle.net/2115/71149https://eprints.lib.hokudai.ac.jp/dspace/bitstream/2115/71149/1/cpc_sigma15.pdf1674-1137AA12308610Chinese Physics C3960641032015-06enginfo:doi/10.1088/1674-1137/39/6/064103© Copyright 2018 IOP Publishingauthor