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arXiv · 2601.00063

Freeze-in leptogenesis without the need for right-handed neutrino oscillations

Martin A. Mojahed·Sascha Weber
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Abstract

We present an experimentally testable leptogenesis mechanism based on the standard type-I seesaw model that successfully operates at right-handed-neutrino (RHN) masses around the GeV scale. The mechanism takes place in a cosmological background with an asymmetry between right-handed electrons and left-handed positrons generated at high temperatures, and does not require oscillations between RHNs or any CP violation in the RHN sector. In contrast to standard leptogenesis via freeze-in, our mechanism works even in the presence of a single RHN around the GeV scale. The mechanism is illustrated for the minimal type-I seesaw with two RHNs, where we show that successful baryogenesis via leptogenesis is viable in large regions of parameter space even without a small mass splitting between the RHNs.

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Martin A. Mojahed, Sascha Weber. 2025-12-31. Freeze-in leptogenesis without the need for right-handed neutrino oscillations. https://arxiv.org/abs/2601.00063

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