Gauged Q-balls in the Affleck-Dine mechanism

TL;DR

This paper investigates gauged Q-balls within a gravity-mediation model of the Affleck-Dine mechanism, revealing that stable solutions with arbitrary charge and size exist, with properties influenced by the parameter K and charge distribution.

Contribution

It demonstrates the existence of stable gauged Q-balls of any size and charge in a specific gravity-mediation potential, contrasting with previous models that had upper limits.

Findings

Stable solutions exist for any charge and size.

Field configurations become shell-like at high charge.

Two solution sequences approach and recombine as |K| increases.

Abstract

We consider gauged Q-balls in the gravity-mediation-type model in the Affleck-Dine mechanism, which is described by the potential $V_{\rm grav.}(\phi):=(m_{\rm grav.}^2/2)\phi^2\left[1+K\ln(\phi/M)^2\right]$ with $K<0$. In many models of gauged Q-balls, which were studied in the literature, there are upper limits for charge and size of Q-balls due to repulsive Coulomb force. In the present model, by contrast, our numerical calculation strongly suggests that stable solutions with any amount of charge and size exist. As the electric charge $Q$ increases, the field configuration of the scalar field becomes shell-like; because the charge is concentrated on the surface, the Coulomb force does not destroy the Q-ball configuration. These properties are analogous to those in the V-shaped model, which was studied by Arod\'z and Lis. We also find that for each $K$ there is another sequence of unstable solutions, which is separated from the other sequence of the stable solutions. As $|K|$ increases, the two sequences approach; eventually at some point in $-1.07<K<-1.06$, the "recombination" of the two sequences takes place.