$S$-matrix representation of the finite temperature propagator in $\lambda {\varphi }^4$-QFT

A. I. Bugrij, L. L. Jenkovszky, V. N. Shadura

The two-point Green function of the massive scalar $(3+1)$-quantum field theory with $\lambda {\varphi }^4$ interaction at finite temperature is evaluated up to the 2nd order of perturbation theor…