This paper is a slightly modified version of the introductory part of a doctoral dissertation that contained also three original articles, hep-ph/0212283, hep-ph/0305183 and hep-ph/0311323. Our purpose is to review the history and present status of finite-temperature perturbation theory as applied to the context of determining the equilibrium properties of quark-gluon plasma, most notably the p...

We demonstrate the relation of the infrared anomaly of conformal field theory with entropy considerations of finite temperature thermodynamics for the 3-state Potts chain. We compute the free energy and compute the low temperature specific heat for both the ferromagnetic and anti-ferromagnetic spin chains, and find the central charges for both.

We calculate the ultra-relativistic Bose-Einstein condensation temperature of a complex scalar field with weak λ(Φ†Φ)2 interaction. We show that at high temperature and finite density we can use dimensional reduction to produce an effective three-dimensional theory which then requires non-perturbative analysis. For simplicity and ease of implementation we illustrate this process with the linear...

We utilize lattice simulations of the dimensionally reduced effective field theory (EQCD) to determine the quark number susceptibility of QCD at high temperature (T > 2T c). We also use analytic continuation to obtain results at finite density. The results extrapolate well from known perturbative expansion (accurate in extremely high temperatures) to 4d lower temperature lattice data.

The spherically symmetric layer of matter is considered within the frameworks of general relativity. We perform generalization of the already known theory for the case of nonconstant surface entropy and finite temperature. We also propose the minisuperspace model to determine the behavior of temperature field and perform the Wheeler-DeWitt quantization. PACS number(s): 04.20.Fy, 04.40.Nr, 04.60...

The Z Z(N) center symmetry plays an important role in the deconfine-ment phase transition of SU(N) Yang-Mills theory at finite temperature. The exceptional group G(2) is the smallest simply connected gauge group with a trivial center. Hence, there is no symmetry reason why the low-and high-temperature regimes in G(2) Yang-Mills theory should be separated by a phase transition. Still, we present...