Dynamics of Q-Balls in an expanding universe

Abstract

We analyse the evolution of light Q-balls in a cosmological background, and find a number of interesting features. For Q-balls formed with a size comparable to the Hubble radius, we demonstrate that there is no charge radiation, and that the Q-ball maintains a constant physical radius. Large expansion rates cause charge migration to the surface of the Q-ball, corresponding to a non-homogeneous internal rotation frequency. We argue that this is an important phenomenon as it leads to a large surface charge and possible fragmentation of the Q-ball. We also explore the deviation of the Q-ball profile function from the static case. By introducing a parameter $\epsilon$, which is the ratio of the Hubble parameter to the frequency of oscillation of the Q-ball field, and using solutions to an analytically approximated equation for the profile function, we determine the dependence of the new features on the expansion rate. This allows us to gain an understanding of when they should be considered and when they can be neglected, thereby placing restrictions on the existence of homogeneous Q-balls in expanding backgrounds.

arXiv comment5 pages, 4 figures

References in corpus (7)

• Supersymmetric Q-balls as dark matter
• Q-Balls and Baryogenesis in the MSSM
• Q-ball Formation through Affleck-Dine Mechanism
• Q-ball candidates for self-interacting dark matter
• The Dynamics of Affleck-Dine Condensate Collapse
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• Q-balls Formation and the Production of Gravitational Waves With Non-minimal Gravitational Coupling
• On Q-balls in Anti de Sitter Space
• Gravitational effects on critical Q-balls
• RN-AdS Nontopoligical Solitons in Broken Einstein-Maxwell-Higgs Theory