Instability of Baryonic Black Branes

TL;DR

This paper investigates the stability of baryonic black branes in a conformal gauge theory, revealing a critical instability at low temperatures and identifying a new ordered phase characterized by a specific operator expectation value.

Contribution

It demonstrates the dynamical instability of baryonic black branes below a critical temperature-to-chemical potential ratio and uncovers a novel ordered phase with a dimension-2 operator expectation value.

Findings

Identification of a diffusive mode with negative diffusion coefficient indicating instability.

Existence of a new ordered phase with ${ m O}_2 eq 0$ at high temperatures.

Critical temperature-to-chemical potential ratio $T_c/$ for phase transition.

Abstract

Baryonic black branes describe the quantum critical phase of the conformal conifold gauge theory at strong coupling. This phase extends to zero temperature at a finite baryonic chemical potential, represented by extremal black branes with $AdS_2\times R^3\times T^{1,1}$ throat in asymptotic $AdS_5\times T^{1,1}$ geometry. We demonstrate here that this phase is dynamically unstable below some critical value of $T_c/\mu$: the instability is represented by a diffusive mode in the hydrodynamic sound channel with a negative diffusion coefficient. We also identify a new (exotic) ordered phase of the conifold gauge theory: this phase originates at the same critical value of $T_c/\mu$, but extends to arbitrary high temperatures, and is characterized by an expectation value of a dimension-2 operator, ${\cal O}_2\propto T^2$, in the limit $\frac \mu T\to 0$.