Narrow Results

Following Aharony et al., we analyze the deconfining phase transition in a SU(∞) gauge theory in mean field approximation. The Gross–Witten model emerges as an "ultra"-critical point for deconfinement: while thermodynamically of first order, masses vanish, asymmetrically, at the transition. Potentials for N = 3 are also shown.

Using an effective model for the quantum chromodynamics we study the color deconfinement effects on the chiral transition. We argue that effects of the color deconfinement are important in the chiral limit. As an example we consider in detail the case of two flavors of massless quarks and find that the corresponding chiral transition can be of first order due to the effects of color deconfinement. This is contrary to the conventional expectations that 2-flavor chiral transition is of second order.

We give a re-interpretation of an 'entropy defect' in the electromagnetic Casimir effect. The electron gas in a perfect crystal is an electromagnetically disordered system whose entropy contains a finite Casimir-like contribution. The Nernst theorem (third law of thermodynamics) is not applicable.

The fragmentation function at high energy experiments is introduced by using thermofield dynamics (TFD), a real-time finite-temperature quantum field formalism. Due to the structure of TFD, the results at T = 0 and T ≠ 0 are split in a direct way. As an application, we consider the temperature effect on the fragmentation function of a hadron leading to quark–antiquark pairs. Using a definition of Wilson-loop in real-time, we find that the fragmentation function decreases in magnitude with an increase in the temperature.