Lepton Asymmetric Universe

TL;DR

This paper explores how the Affleck-Dine mechanism can generate large lepton asymmetry in the universe through the formation and evolution of L-balls, aligning with recent helium-4 observations.

Contribution

It demonstrates that L-balls can effectively produce and preserve large lepton asymmetry, providing a viable explanation consistent with recent experimental data.

Findings

L-balls can contain significant lepton number

Large lepton asymmetry is compatible with helium-4 observations

L-balls prevent lepton-to-baryon conversion via sphalerons

Abstract

The recent observation of $^4$He implies that our universe has a large lepton asymmetry. We consider the Affleck-Dine (AD) mechanism for lepton number generation. In the AD mechanism, non-topological solitons called L-balls are produced, and the generated lepton number is confined in them. The L-balls protect the generated lepton number from being converted to baryon number through the sphaleron processes. We study the formation and evolution of the L-balls and find that the universe with large lepton asymmetry suggested by the recent $^4$He measurement can be realized.