Hydrodynamic Stability of Cosmological Quark-Hadron Phase Transitions

TL;DR

This paper investigates the nonlinear hydrodynamic stability of cosmological quark-hadron phase transitions, using numerical simulations to analyze perturbation growth in different transition modes and configurations.

Contribution

It provides the first nonlinear numerical analysis of quark-hadron phase transition stability, including detonation and deflagration modes with complex interactions.

Findings

Nonlinear effects can significantly influence perturbation growth.

Detonation transitions may lead to unstable modes.

Deflagration transitions show borderline stability.

Abstract

Recent results from linear perturbation theory suggest that first-order cosmological quark-hadron phase transitions occurring as deflagrations may be ``borderline'' unstable, and those occurring as detonations may give rise to growing modes behind the interface boundary. However, since nonlinear effects can play important roles in the development of perturbations, unstable behavior cannot be asserted entirely by linear analysis, and the uncertainty of these recent studies is compounded further by nonlinearities in the hydrodynamics and self-interaction fields. In this paper we investigate the growth of perturbations and the stability of quark-hadron phase transitions in the early Universe by solving numerically the fully nonlinear relativistic hydrodynamics equations coupled to a scalar field with a quartic self-interaction potential regulating the transitions. We consider single, perturbed, phase transitions propagating either by detonation or deflagration, as well as multiple phase and shock front interactions in 1+2 dimensional spacetimes.