Equation of State of Gluon Plasma from Fundamental Modular Region

Abstract

Numerical studies of the bulk properties of the quark-gluon plasma reveal a pronounced drop in pressure $p$ compared to energy density $\e$ as the deconfining temperature is approached from above. We show by general thermodynamic reasoning that this can be explained only by a term $LT$ in the trace anomaly $\th(T) = \e - 3p$ that is linear in the temperature $T$. Such a term appears in the equation of state of the gluon plasma, which we calculate, described as a gas of quasi-particle gluons with dispersion relation $E(k) = \sqrt{k^2 + {M^4 \over k^2}}$, that follows from the restriction of the configuration space to the fundamental modular region.