Lepton number violation from Higgs/$Z$ decays into a pair of right-handed neutrinos
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arXiv
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| Natura: | Preprint |
| Pubblicazione: |
2025
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| _version_ | 1866917121332609024 |
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| author | Das, Arindam Nomura, Takaaki Yagyu, Kei |
| author_facet | Das, Arindam Nomura, Takaaki Yagyu, Kei |
| contents | We explore signatures of Lepton Number Violation (LNV) from decays of the discovered Higgs ($h$) and Z bosons into a pair of Right-Handed Neutrinos (RHNs). Due to the Majorana nature of RHNs, the final state can be the same-sign dilepton plus jets leading to 2 units of LNV. As a simple but plausible scenario, we investigate such a signal in models with a new $U(1)_X$ gauge symmetry which naturally introduces three RHNs for gauge anomaly cancellation, and is spontaneously broken down by a vacuum expectation value of an isospin singlet scalar field ($ϕ$). In this scenario, $h$ and the Z boson can decay into a pair of RHNs via the $h$-$ϕ$ mixing and the $Z$-$Z'$ mixing with $Z'$ being a new massive gauge boson, respectively. Estimating the LNV signal and corresponding backgrounds for the $\ell^{\pm} \ell^{\pm} 4j$ final states, we find bounds on the $h$-$ϕ$ mixing and the $Z$-$Z^\prime$ mixing as a function of a mass of RHNs at Higgs factories, e.g., at High-Luminosity LHC with $\sqrt{s}=$ 14 TeV, future $e^-e^+$ colliders at $\sqrt{s}=$ 250 GeV, muon colliders at $\sqrt{s}=$ 125 GeV as well as at Z factories, e.g., CEPC and FCC-ee at $\sqrt{s}=$ 91.2 GeV. We also discuss limits on the scalar mixing at $e^-μ^+$ and $μ^+ μ^+$ collisions ($μ$TRISTAN) with $\sqrt{s}=$346 GeV/775 GeV and 2 TeV, respectively. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2512_03302 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Lepton number violation from Higgs/$Z$ decays into a pair of right-handed neutrinos Das, Arindam Nomura, Takaaki Yagyu, Kei High Energy Physics - Phenomenology We explore signatures of Lepton Number Violation (LNV) from decays of the discovered Higgs ($h$) and Z bosons into a pair of Right-Handed Neutrinos (RHNs). Due to the Majorana nature of RHNs, the final state can be the same-sign dilepton plus jets leading to 2 units of LNV. As a simple but plausible scenario, we investigate such a signal in models with a new $U(1)_X$ gauge symmetry which naturally introduces three RHNs for gauge anomaly cancellation, and is spontaneously broken down by a vacuum expectation value of an isospin singlet scalar field ($ϕ$). In this scenario, $h$ and the Z boson can decay into a pair of RHNs via the $h$-$ϕ$ mixing and the $Z$-$Z'$ mixing with $Z'$ being a new massive gauge boson, respectively. Estimating the LNV signal and corresponding backgrounds for the $\ell^{\pm} \ell^{\pm} 4j$ final states, we find bounds on the $h$-$ϕ$ mixing and the $Z$-$Z^\prime$ mixing as a function of a mass of RHNs at Higgs factories, e.g., at High-Luminosity LHC with $\sqrt{s}=$ 14 TeV, future $e^-e^+$ colliders at $\sqrt{s}=$ 250 GeV, muon colliders at $\sqrt{s}=$ 125 GeV as well as at Z factories, e.g., CEPC and FCC-ee at $\sqrt{s}=$ 91.2 GeV. We also discuss limits on the scalar mixing at $e^-μ^+$ and $μ^+ μ^+$ collisions ($μ$TRISTAN) with $\sqrt{s}=$346 GeV/775 GeV and 2 TeV, respectively. |
| title | Lepton number violation from Higgs/$Z$ decays into a pair of right-handed neutrinos |
| topic | High Energy Physics - Phenomenology |
| url | https://arxiv.org/abs/2512.03302 |