Electromagnetic leptogenesis with light-heavy sterile neutrinos

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Autori principali: Borah, Debasish, Dasgupta, Arnab
Natura: Preprint
Pubblicazione: 2025
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author Borah, Debasish
Dasgupta, Arnab
author_facet Borah, Debasish
Dasgupta, Arnab
contents 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 $N_R$ and its lighter counterpart $ν_R$. This allows the generation of lepton asymmetry in $ν_R$ 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 $ν_R$ rendering the light neutrinos to be Majorana fermions. While smallness of the Majorana mass of $ν_R$ prevents additional sources or washout of lepton asymmetry, it also constrains the scale of leptogenesis. For $\mathcal{O}(10)$ TeV scale leptogenesis, this leads to additional sterile neutrinos lighter than a few keV with interesting implications for a variety of observables including neutrino oscillation, warm dark matter as well as effective degrees of freedom within reach of future cosmic microwave background experiments. Additionally, heavy RHN can lead to observable monochromatic photon signatures at terrestrial experiments.
format Preprint
id arxiv_https___arxiv_org_abs_2501_13150
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Electromagnetic leptogenesis with light-heavy sterile neutrinos
Borah, Debasish
Dasgupta, Arnab
High Energy Physics - Phenomenology
Cosmology and Nongalactic Astrophysics
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 $N_R$ and its lighter counterpart $ν_R$. This allows the generation of lepton asymmetry in $ν_R$ 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 $ν_R$ rendering the light neutrinos to be Majorana fermions. While smallness of the Majorana mass of $ν_R$ prevents additional sources or washout of lepton asymmetry, it also constrains the scale of leptogenesis. For $\mathcal{O}(10)$ TeV scale leptogenesis, this leads to additional sterile neutrinos lighter than a few keV with interesting implications for a variety of observables including neutrino oscillation, warm dark matter as well as effective degrees of freedom within reach of future cosmic microwave background experiments. Additionally, heavy RHN can lead to observable monochromatic photon signatures at terrestrial experiments.
title Electromagnetic leptogenesis with light-heavy sterile neutrinos
topic High Energy Physics - Phenomenology
Cosmology and Nongalactic Astrophysics
url https://arxiv.org/abs/2501.13150