Indications for a Nonzero Lepton Asymmetry from Extremely Metal-Poor Galaxies
Abstract
The recent measurement of helium-4 from the near-infrared spectroscopy of extremely metal-poor galaxies (EMPGs) by the Subaru Survey may point to a new puzzle in the Early Universe. We exploit this new helium measurement together with the percent-level determination of primordial deuterium, to assess indications for a non-vanishing lepton asymmetry during the Big Bang Nucleosynthesis (BBN) era, paying particular attention to the role of uncertainties in the nuclear reaction network. A cutting-edge Bayesian analysis focused on the role of the newly measured EMPGs, jointly with information from the Cosmic Microwave Background, suggests the existence of a nonzero lepton asymmetry at around the level, providing a hint for cosmology beyond CDM. We discuss conditions for a large total lepton asymmetry to be consistently realized in the Early Universe.
Keywords
Cite
@article{arxiv.2206.00693,
title = {Indications for a Nonzero Lepton Asymmetry from Extremely Metal-Poor Galaxies},
author = {Anne-Katherine Burns and Tim M. P. Tait and Mauro Valli},
journal= {arXiv preprint arXiv:2206.00693},
year = {2023}
}
Comments
Analysis updated with Astrophys.J. 941 (2022) 2, 167. 95% joint probability distribution now shown in Fig.1. Minor modifications of the text, conclusions unchanged. Version matches publication in Physical Review Letters