Testing Leptogenesis via CP asymmetries in Lepton-Number-Violating W Decays at Colliders
Abstract
In principle, searches for CP asymmetries in rare W-boson decays can test low-scale leptogenesis in the GeV-scale type-I seesaw with three quasi-degenerate-in-mass heavy right-handed neutrinos. To investigate this, we focus on the lepton-number-violating heavy-neutrino-mediated decay W±→ e± e± (q̅ q')∓, with (q̅ q')+ = (d̅u)+ and (q̅ q')- = (u̅d)-. We determine the minimum branching ratio required for a CP asymmetry to be observable at colliders with a given statistical significance. We then perform a numerical scan of the presently-allowed parameter space, also solving the density matrix equations for low-scale leptogenesis, and identify regions where, simultaneously, the present baryon asymmetry of the Universe can be achieved and the collider CP asymmetry for the considered decay is observable at HL-LHC and FCC-hh. We find that these regions are sizeable. A future observation of a CP asymmetry in W±→ e± e± (q̅ q')∓ within the regions identified here would provide evidence in favour of low-scale leptogenesis as the origin of the matter-antimatter asymmetry of the Universe.
Related
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- Lepton Flavor Violating Higgs decays at the Compact Linear Collider
- Multiboson production at multi-TeV lepton colliders as complementary probes to rare Higgs decays
- Probing Lepton-Flavor-Violating Four-Lepton Operators at a Muon Collider
BibTeX
@misc{fortin2026testing,
title = {{Testing Leptogenesis via CP asymmetries in Lepton-Number-Violating $W$ Decays at Colliders}},
author = {Jean-François Fortin and Alessandro Granelli and David London and Serguey T. Petcov and Nicolas Sanfaçon},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.24063},
eprint = {2610.24063},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.24063},
}
RIS
TY - UNPB
TI - Testing Leptogenesis via CP asymmetries in Lepton-Number-Violating W Decays at Colliders
AU - Jean-François Fortin
AU - Alessandro Granelli
AU - David London
AU - Serguey T. Petcov
AU - Nicolas Sanfaçon
PY - 2026
DA - 2026/10/16
PB - arXiv
DO - 10.48550/arxiv.2610.24063
UR - https://arxiv.org/abs/2610.24063
AB - In principle, searches for CP asymmetries in rare W-boson decays can test low-scale leptogenesis in the GeV-scale type-I seesaw with three quasi-degenerate-in-mass heavy right-handed neutrinos. To investigate this, we focus on the lepton-number-violating heavy-neutrino-mediated decay W^±→ e^± e^± (q̅ q')^∓, with (q̅ q')^+ = (d̅u)^+ and (q̅ q')^- = (u̅d)^-. We determine the minimum branching ratio required for a CP asymmetry to be observable at colliders with a given statistical significance. We then perform a numerical scan of the presently-allowed parameter space, also solving the density matrix equations for low-scale leptogenesis, and identify regions where, simultaneously, the present baryon asymmetry of the Universe can be achieved and the collider CP asymmetry for the considered decay is observable at HL-LHC and FCC-hh. We find that these regions are sizeable. A future observation of a CP asymmetry in W^±→ e^± e^± (q̅ q')^∓ within the regions identified here would provide evidence in favour of low-scale leptogenesis as the origin of the matter-antimatter asymmetry of the Universe.
ER -