Hydrodynamic and Rayleigh-Plateau instabilities of Q-strings

TL;DR

This paper investigates the stability of cylindrical Q-strings, revealing a long-wavelength dynamical instability akin to fluid surface phenomena, which can lead to Q-ball formation and resembles black string behavior.

Contribution

It demonstrates that Q-strings exhibit a Rayleigh-Plateau-like instability, linking soliton dynamics to fluid instabilities and providing new insights into their stability properties.

Findings

Q-strings are unstable to perturbations with wavelengths exceeding a critical value.

The instability can lead to the formation of Q-balls from Q-strings.

Q-strings behave similarly to low-viscosity fluids with surface tension.

Abstract

As analogues of compact objects, solitons have attracted significant attention. We reveal that cylindrical Q-strings exhibit a dynamical instability to perturbations with wavelengths exceeding a threshold $\lambda>\lambda_{c}$. This instability can destroy the invariance in the cylindrical direction, as a generation mechanism for Q-balls, similar to the formation of droplets. As the interface of Q-strings approaches a thin wall, this long-wavelength instability degenerates into the Rayleigh-Plateau instability with a threshold related only to the geometric radius $\lambda_{c}=2\pi R$. Such results indicate that Q-strings, like black strings, resemble low-viscosity fluids with surface tension.