Entropy production by Q-ball decay for diluting long-lived charged particles

TL;DR

This paper investigates how large Q balls, arising in gauge-mediated supersymmetry breaking, can produce significant entropy through decay, effectively diluting long-lived charged particles like staus that threaten standard nucleosynthesis constraints.

Contribution

It demonstrates that large Q balls can generate enough entropy upon decay to dilute problematic long-lived charged particles in the early universe.

Findings

Large Q balls can produce sufficient entropy for dilution.

Q balls naturally form in gauge-mediated SUSY breaking.

Dilution helps evade big bang nucleosynthesis constraints.

Abstract

The cosmic abundance of a long-lived charged particle such as a stau is tightly constrained by the catalyzed big bang nucleosynthesis. One of the ways to evade the constraints is to dilute those particles by a huge entropy production. We evaluate the dilution factor in a case that non-relativistic matter dominates the energy density of the universe and decays with large entropy production. We find that large Q balls can do the job, which is naturally produced in the gauge-mediated supersymmetry breaking scenario.