Q-ball decay through A-term in the gauge-mediated SUSY breaking scenario

TL;DR

This paper investigates how A-term effects influence Q-ball decay in gauge-mediated SUSY breaking, assessing their viability as dark matter and their interactions with neutron stars.

Contribution

It provides a detailed analysis of Q-ball stability and growth constraints considering A-term effects in gauge-mediated SUSY scenarios, expanding understanding of Q-ball dark matter viability.

Findings

Q-balls can serve as dark matter within certain parameter ranges.

A-term effects can halt Q-ball growth in neutron stars.

Revised constraints expand the allowed Q-ball parameter space.

Abstract

Q-balls are non-topological solitons whose classical stability is ensured by a global $U(1)$ charge. In particular, Q-balls are produced in the framework of the Affleck-Dine baryogenesis where $U(1)$ charge is the baryon number. Since some type of Q-balls is stable against quantum decay into nucleons, it can work as the dark matter. When the dark matter Q-balls are captured into the neutron star, they absorb the surrounding neutrons and grow to consume all the neutrons, which leads to a stringent constraint on the Q-ball dark matter. However, the Q-ball growth stops due to the $U(1)$ breaking A-term. We revisit the constraint by the neutron star for the gauge-mediation type and the new type Q-ball, and find the allowed parameter space, in which Q-balls work as the dark matter.