CP violation in neutral lepton transition dipole moment

Balaji, Shyam; Ramirez-Quezada, Maura; Zhou, Ye-Ling

Abstract

The CP violation in the neutrino transition electromagnetic dipole moment is discussed in the context of the Standard Model with an arbitrary number of right-handed singlet neutrinos. A full one-loop calculation of the neutrino electromagnetic form factors is performed in the Feynman gauge. A non-zero CP asymmetry is generated by a required threshold condition for the neutrino masses along with non-vanishing CP violating phases in the lepton flavour mixing matrix. We follow the paradiagm of CP violation in neutrino oscillations to parametrise the flavour mixing contribution into a series of Jarlskog-like parameters. This formalism is then applied to a minimal seesaw model with two heavy right-handed neutrinos denoted N1 and N2. We observe that the CP asymmetries for decays into light neutrinos N → νγ are extremely suppressed, maximally around 10−17. However the CP asymmetry for N2 → N1γ can reach of order unity. Even if the Dirac CP phase δ is the only source of CP violation, a large CP asymmetry around 10−5–10−3 is comfortably achieved.

Citation

Balaji, S., Ramirez-Quezada, M., & Zhou, Y. (2020). CP violation in neutral lepton transition dipole moment. Journal of High Energy Physics, 2020(12), Article 90. https://doi.org/10.1007/jhep12%282020%29090

• Journal Article Type: Article
• Acceptance Date: Nov 4, 2020
• Online Publication Date: Dec 15, 2020
• Publication Date: 2020-12
• Deposit Date: Apr 13, 2021
• Publicly Available Date: Apr 13, 2021
• Journal: Journal of High Energy Physics
• Print ISSN: 1126-6708
• Publisher: Scuola Internazionale Superiore di Studi Avanzati (SISSA)
• Peer Reviewed: Peer Reviewed
• Volume: 2020
• Issue: 12
• Article Number: 90
• DOI: https://doi.org/10.1007/jhep12%282020%29090
• Public URL: https://durham-repository.worktribe.com/output/1249914
• Related Public URLs: https://arxiv.org/abs/2008.12795