A simple description of holographic domain walls in confining theories -- extended hydrodynamics

TL;DR

This paper introduces a covariant framework for describing domain walls in theories with phase transitions, extending hydrodynamics and providing analytic profiles that match holographic numerical solutions.

Contribution

It presents a novel covariant description of phase-separated domain walls in holographic models, incorporating an additional order parameter and extending hydrodynamics.

Findings

Analytic domain wall profiles derived and validated against holographic solutions

Expressions for surface tension density obtained and shown to agree with numerical data

Extended hydrodynamics formulated in a simple spacetime action

Abstract

In the context of theories with a first order phase transition, we propose a general covariant description of coexisting phases separated by domain walls using an additional order parameter-like degree of freedom. In the case of a holographic Witten model with a confining and deconfined phase, the resulting model extends hydrodynamics and has a simple formulation in terms of a spacetime action with corresponding expressions for the energy-momentum tensor. The proposed description leads to simple analytic profiles of domain walls, including expressions for surface tension density, which agree nicely with holographic numerical solutions, despite the apparent complexity of those gravitational backgrounds.