Finite-temperature φ ⁴ theory from the 2PI effective action: Two-loop truncation

Using resummation techniques based on the 2PI effective action we study the scalar φ ⁴ theory at finite temperature. We present an analytical as well as numerical study for a renormalized two-loop truncation of the action. Both the spectral properties and critical behaviour of the theory are investigated. Within the truncation, we explicitly check that the physical observables are UV-finite.