Axion-driven spontaneous leptogenesis, precisely
5 affiliations
- 1University of Münster
- 2Istituto Nazionale di Fisica Nucleare (INFN) Sezione di Roma
- 3The University of Tokyo
- 4Theory Center, Institute of Particle and Nuclear Studies, KEK
- 5Graduate University for Advanced Studies (Sokendai)
Abstract
A bstract : We revisit a minimal scenario for spontaneous leptogenesis where the asymmetry generation is driven by a heavy axion-like field evolving via standard misalignment. We focus on the simplest framework in which lepton number violation originates from the dimension-five Weinberg operator and contributions from standard thermal leptogenesis become negligible. The asymmetry is computed by solving a set of transport equations, which incorporate fully flavor-dependent interaction rates for the Weinberg operator that are presented here for the first time. We also derive a simple algebraic master formula for the generated B – L asymmetry, valid for arbitrary axion velocities and classically shift-symmetric couplings to the Standard Model, that reproduces the B – L -production dynamics of the full set of transport equations in controlled parameter regions. Along the way, we quantify the importance of low-scale neutrino masses and the two mass orderings on the final prediction for the generated asymmetry. Finally, we assess the cosmological viability of different axion couplings by accounting for entropy dilution from late-time axion decays and imposing constraints from baryonic isocurvature perturbations. We demonstrate that explaining the baryon asymmetry via standard Majoron misalignment is under severe tension due to dilution from late-time decays. In contrast, axions coupled to strong or weak sphalerons can successfully produce the observed asymmetry for decay constants near the energy scale of grand unification and axion oscillation temperatures T osc ≳ 10 11···12 GeV, provided a cosmological history featuring high-scale inflation and efficient reheating.
Versions
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BibTeX
@article{kuckenberg2026axiondriven,
title = {{Axion-driven spontaneous leptogenesis, precisely}},
author = {Konstantin Kuckenberg and Martin A. Mojahed and Kai Schmitz and Hidenaga Watanabe},
journal = {Journal of High Energy Physics},
year = {2026},
month = oct,
doi = {10.1007/jhep10(2026)218},
url = {https://link.springer.com/article/10.1007/JHEP10(2026)218},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Axion-driven spontaneous leptogenesis, precisely
AU - Konstantin Kuckenberg
AU - Martin A. Mojahed
AU - Kai Schmitz
AU - Hidenaga Watanabe
PY - 2026
DA - 2026/10/21
JO - Journal of High Energy Physics
DO - 10.1007/jhep10(2026)218
UR - https://link.springer.com/article/10.1007/JHEP10(2026)218
AB - A bstract : We revisit a minimal scenario for spontaneous leptogenesis where the asymmetry generation is driven by a heavy axion-like field evolving via standard misalignment. We focus on the simplest framework in which lepton number violation originates from the dimension-five Weinberg operator and contributions from standard thermal leptogenesis become negligible. The asymmetry is computed by solving a set of transport equations, which incorporate fully flavor-dependent interaction rates for the Weinberg operator that are presented here for the first time. We also derive a simple algebraic master formula for the generated B – L asymmetry, valid for arbitrary axion velocities and classically shift-symmetric couplings to the Standard Model, that reproduces the B – L -production dynamics of the full set of transport equations in controlled parameter regions. Along the way, we quantify the importance of low-scale neutrino masses and the two mass orderings on the final prediction for the generated asymmetry. Finally, we assess the cosmological viability of different axion couplings by accounting for entropy dilution from late-time axion decays and imposing constraints from baryonic isocurvature perturbations. We demonstrate that explaining the baryon asymmetry via standard Majoron misalignment is under severe tension due to dilution from late-time decays. In contrast, axions coupled to strong or weak sphalerons can successfully produce the observed asymmetry for decay constants near the energy scale of grand unification and axion oscillation temperatures T osc ≳ 10 11···12 GeV, provided a cosmological history featuring high-scale inflation and efficient reheating.
SN - 1029-8479
ER -