Electromagnetic leptogenesis with light-heavy sterile neutrinos
We propose a novel leptogenesis scenario utilising the two-body decay of heavy right handed neutrino (RHN) via the electromagnetic dipole operator. While the requirement of the standard model (SM) gauge invariance requires such dipole operator only at dimension-6 forcing the generation of non-zero C...
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| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Elsevier
2025-07-01
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| Series: | Physics Letters B |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S0370269325003181 |
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| Summary: | We propose a novel leptogenesis scenario utilising the two-body decay of heavy right handed neutrino (RHN) via the electromagnetic dipole operator. While the requirement of the standard model (SM) gauge invariance requires such dipole operator only at dimension-6 forcing the generation of non-zero CP asymmetry from three-body decay with two-loop corrections, we write down dimension-5 dipole operators involving heavy RHN NR and its lighter counterpart νR. This allows the generation of lepton asymmetry in νR from two-body decay of heavy RHN which later gets transferred to left handed leptons via sizeable Yukawa coupling with a neutrinophilic Higgs doublet. The asymmetry in left handed leptons is then converted to baryon asymmetry via electroweak sphalerons. The lepton number violation by heavy RHN also induces a one-loop Majorana mass of νR rendering the light neutrinos to be Majorana fermions. While smallness of the Majorana mass of νR prevents additional sources or washout of lepton asymmetry, it also constrains the scale of leptogenesis. Sub-GeV sterile neutrinos, depending upon their masses come with interesting implications for low energy experiments, neutrino oscillation, warm dark matter as well as effective relativistic degrees of freedom. Additionally, heavy RHN can lead to observable monochromatic photon signatures at terrestrial experiments. |
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| ISSN: | 0370-2693 |