QNEC2 in deformed holographic CFTs

TL;DR

This paper uses the quantum null energy condition (QNEC2) to analyze phase transitions in strongly coupled 2D field theories, revealing universal constraints and predicting phase transitions via holographic dual models.

Contribution

It introduces QNEC2 as a diagnostic for various phase transitions in holographic models and explores its relation to the c-function and phase structure predictions.

Findings

QNEC2 constrains phase transition types with kinked entanglement entropy.

The c-function behavior correlates with phase transition order.

QNEC2 can predict finite temperature phase transitions from ground states.

Abstract

We use the quantum null energy condition in strongly coupled two-dimensional field theories (QNEC2) as diagnostic tool to study a variety of phase structures, including crossover, second and first order phase transitions. We find a universal QNEC2 constraint for first order phase transitions with kinked entanglement entropy and discuss in general the relation between the QNEC2-inequality and monotonicity of the Casini-Huerta c-function. We then focus on a specific example, the holographic dual of which is modelled by three-dimensional Einstein gravity plus a massive scalar field with one free parameter in the self-interaction potential. We study translation invariant stationary states dual to domain walls and black branes. Depending on the value of the free parameter we find crossover, second and first order phase transitions between such states, and the c-function either flows to zero or to a finite value in the infrared. Strikingly, evaluating QNEC2 for ground state solutions allows to predict the existence of phase transitions at finite temperature.