Work

Delayed Charged Lepton Yukawa Equilibration in Minimal Seesaw

Year: 2026

Type: article

Abstract: While most studies of the minimal type-I seesaw neglect the heaviest decoupled right-handed neutrino, assuming negligible contributions to neutrino masses and leptogenesis, we demonstrate that its cosmological role can be significant. When long-lived, the presence of this particle can substantially modify the charged lepton Yukawa equilibration temperature in the early universe, necessitating reassessment of lepton flavor effects in thermal leptogenesis and potentially shifting flavor regime boundaries. Additionally, we identify experimental probes, including neutrino oscillation measurements and gravitational wave observations to investigate this scenario. More broadly, the resulting modification of the cosmic expansion history carries implications beyond leptogenesis, impacting dark matter production and evolution, the matter-antimatter asymmetry generation, and the primordial gravitational wave spectrum.

Source: Physical Review Letters

DOI: 10.1103/nfkx-q6z7

Authors: Rishav Roshan, Sudipta Show

Institutions: University of Southampton, Indian Institute of Technology Kanpur

Language: English

Topic: Particle physics theoretical and experimental studies

Subfield: Nuclear and High Energy Physics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $3,750

Funders: National Niemann-Pick Disease Foundation, European Cooperation in Science and Technology, Science and Technology Facilities Council, Science and Engineering Research Board