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| Format: | Preprint |
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2023
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| Online Access: | https://arxiv.org/abs/2309.14281 |
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| _version_ | 1866929258902847488 |
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| author | Cvetic, Gorazd Kim, C. S. |
| author_facet | Cvetic, Gorazd Kim, C. S. |
| contents | We investigate rare decays of tau leptons that occur via exchange of heavy on-shell neutrinos $N_j$ ($j=1,2$). These neutrinos can be either Dirac or Majorana, and are considered to be almost degenerate in mass. The decays can thus be either lepton number conserving (LNC), $τ^{\mp} \to π^{\mp} N_j \to π^{\mp} μ^{\mp} π^{\pm}$, or lepton number violating (LNV), $τ^{\mp} \to π^{\mp} N_j \to π^{\mp} μ^{\pm} π^{\mp}$. If neutrinos are Dirac, only LNC decays are possible. If they are Majorana, both LNC and LNV are possible. We derive the corresponding expressions for the effective decay widths $Γ_{{\rm eff},\mp}^{\rm (X)}$ (X=LNC, LNV) of these rare decays, where we account for $N_1$-$N_2$ overlap and oscillation effects and for the finite detector length effects. We then numerically evaluate these decay widths as well as the related CP violation asymmetry width $ΔΓ_{\rm CP}^{\rm (X)} = (Γ_{{\rm eff},-}^{\rm (X)} - Γ_{{\rm eff},+}^{\rm (X)})$. We conclude that for certain, presently allowed, ranges of the heavy-light neutrino mixing parameters, such decays and asymmetries could be observed in Belle II experiment. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2309_14281 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | Rare tau decays via exchange of on-shell almost degenerate Majorana neutrinos, $τ^{\mp} \to π^{\mp} N_j \to π^{\mp} μ^{\mp} π^{\pm}$ and $τ^{\mp} \to π^{\mp} N_j \to π^{\mp} μ^{\pm} π^{\mp}$ Cvetic, Gorazd Kim, C. S. High Energy Physics - Phenomenology We investigate rare decays of tau leptons that occur via exchange of heavy on-shell neutrinos $N_j$ ($j=1,2$). These neutrinos can be either Dirac or Majorana, and are considered to be almost degenerate in mass. The decays can thus be either lepton number conserving (LNC), $τ^{\mp} \to π^{\mp} N_j \to π^{\mp} μ^{\mp} π^{\pm}$, or lepton number violating (LNV), $τ^{\mp} \to π^{\mp} N_j \to π^{\mp} μ^{\pm} π^{\mp}$. If neutrinos are Dirac, only LNC decays are possible. If they are Majorana, both LNC and LNV are possible. We derive the corresponding expressions for the effective decay widths $Γ_{{\rm eff},\mp}^{\rm (X)}$ (X=LNC, LNV) of these rare decays, where we account for $N_1$-$N_2$ overlap and oscillation effects and for the finite detector length effects. We then numerically evaluate these decay widths as well as the related CP violation asymmetry width $ΔΓ_{\rm CP}^{\rm (X)} = (Γ_{{\rm eff},-}^{\rm (X)} - Γ_{{\rm eff},+}^{\rm (X)})$. We conclude that for certain, presently allowed, ranges of the heavy-light neutrino mixing parameters, such decays and asymmetries could be observed in Belle II experiment. |
| title | Rare tau decays via exchange of on-shell almost degenerate Majorana neutrinos, $τ^{\mp} \to π^{\mp} N_j \to π^{\mp} μ^{\mp} π^{\pm}$ and $τ^{\mp} \to π^{\mp} N_j \to π^{\mp} μ^{\pm} π^{\mp}$ |
| topic | High Energy Physics - Phenomenology |
| url | https://arxiv.org/abs/2309.14281 |