$δ$-Expansion at Finite Temperature

Abstract

We apply the $δ$-expansion perturbation scheme to the $λϕ^{4}$ self-interacting scalar field theory in 3+1 D at finite temperature. In the $δ$-expansion the interaction term is written as $λ(ϕ^{2})^{ 1 + δ}$ and $δ$ is considered as the perturbation parameter. We compute within this perturbative approach the renormalized mass at finite temperature at a finite order in $δ$. The results are compared with the usual loop-expansion at finite temperature.