Debye screening mass near deconfinement from holography

Abstract

In this paper the smallest thermal screening mass associated with the correlator of the $CT$-odd operator, $\sim {\rm Tr}F_{\mu\nu}\tilde{F}^{\mu\nu}$, is determined in strongly coupled non-Abelian gauge plasmas which are holographically dual to non-conformal, bottom-up Einstein+scalar gravity theories. These holographic models are constructed to describe the thermodynamical properties of $SU(N_c)$ plasmas near deconfinement at large $N_c$ and we identify this thermal mass with the Debye screening mass $m_D$. In this class of non-conformal models with a first order deconfinement transition at $T_c$, $m_D/T$ displays the same behavior found for the expectation value of the Polyakov loop (which we also compute) jumping from zero below $T_c$ to a nonzero value just above the transition. In the case of a crossover phase transition, $m_D/T$ has a minimum similar to that found for the speed of sound squared $c_s^2$. This holographic framework is also used to evaluate $m_D$ as a function of $\eta/s$ in a strongly coupled conformal gauge plasma dual to Gauss-Bonnet gravity. In this case, $m_D/T$ decreases with increasing $\eta/s$ in accordance with extrapolations from weak coupling calculations.