Two-loop two-particle point irreducible analysis ofλφ4theory at finite temperature

Optimized Perturbation Theory at Finite Temperature Two-Loop Analysis

We study the optimized perturbation theory (OPT) at finite temperature, which is a selfconsistent resummation method. Firstly, we generalize the idea of the OPT to optimize the coupling constant in λφ theory, and give a proof of the renormalizability of this generalized OPT. Secondly, the principle of minimal sensitivity and the criterion of the fastest apparent convergence, which are condition...

Two Polyakov Loop Correlators from D5-branes at Finite Temperature

We study two Polyakov loop correlators in large N limit of N = 4 super Yang-Mills theory at finite temperature using the AdS-Schwarzschild black hole. In the case that one of the two loops is of the anti-symmetric representation, we use D5-branes to evaluate them. The phase structure of these correlators is also examined. A previous result, derived in hep-th/9803135 and hep-th/9803137, is reali...

Two-Loop Self-Energy and Multiple Scattering at Finite Temperature

One and two loop self-energies are worked out explicitly for a heavy scalar field interacting weakly with a light self-interacting scalar field at finite temperature. The ring/daisy diagrams and a set of necklace diagrams can be summed simultaneously. This simple model serves to illustrate the connection between multi-loop self-energy diagrams and multiple scattering in a medium. PACS numbers: ...

QED Effective Action at Finite Temperature: Two-Loop Dominance

We calculate the two-loop effective action of QED for arbitrary constant electromagnetic fields at finite temperature T in the limit of T much smaller than the electron mass. It is shown that in this regime the two-loop contribution always exceeds the influence of the one-loop part due to the thermal excitation of the internal photon. As an application, we study light propagation and photon spl...

On Finite Groups With Two Irreducible Character Degrees