Large Neutrino Asymmetry from TeV Scale Leptogenesis in the Light of Helium Anomaly

Debasish Borah, Arnab Dasgupta

Submitted on 29 June 2022


Motivated by the growing evidence for a large neutrino asymmetry in the early universe from the recent 4He measurements, we point out the class of leptogenesis scenarios with decay or scattering being the source of lepton asymmetry, simultaneously consistent with such a large neutrino asymmetry as well as the observed baryon asymmetry of the universe. Considering 12,13 as well as 22 processes to be responsible for generating the asymmetries, we show that only TeV scale leptogenesis preferably of 1N(N3) type can generate the required lepton asymmetry around sphaleron temperature while also generating a large neutrino asymmetry O(102) by the epoch of the big bang nucleosynthesis. This also offers the possibility of cogenesis if dark matter is in the form of a sterile neutrino resonantly produced in the early universe due to the presence of a large neutrino asymmetry. While such low scale leptogenesis has tantalising detection prospects at laboratory experiments, the indication of a large neutrino asymmetry provides a complementary indirect signature.


Comment: 6 pages, 5 captioned figures

Subjects: High Energy Physics - Phenomenology; Astrophysics - Cosmology and Nongalactic Astrophysics