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arXiv · 2206.00693

Indications for a Nonzero Lepton Asymmetry from Extremely Metal-Poor Galaxies

Anne-Katherine Burns·Tim M. P. Tait·Mauro Valli
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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 $2 \sigma$ level, providing a hint for cosmology beyond $\Lambda$CDM. We discuss conditions for a large total lepton asymmetry to be consistently realized in the Early Universe.

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Anne-Katherine Burns, Tim M. P. Tait, Mauro Valli. 2022-06-01. Indications for a Nonzero Lepton Asymmetry from Extremely Metal-Poor Galaxies. https://doi.org/10.1103/physrevlett.130.131001

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