Z lepton flavour violation as a probe for new physics at future $e^+e^-$ colliders
| Autor: | Calibbi, Lorenzo, Marcano, Xabier, Roy, Joydeep |
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| Rok vydání: | 2021 |
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| Druh dokumentu: | Working Paper |
| DOI: | 10.1140/epjc/s10052-021-09777-3 |
| Popis: | In this work we assess the potential of discovering new physics by searching for lepton-flavour-violating (LFV) decays of the $Z$ boson, $Z\to \ell_i \ell_j$, at the proposed circular $e^+e^-$ colliders CEPC and FCC-ee. Both projects plan to run at the $Z$-pole as a Tera Z factory, i.e., collecting $\mathcal O\left(10^{12}\right)$ $Z$ decays. In order to discuss the discovery potential in a model-independent way, we revisit the LFV $Z$ decays in the context of the Standard Model effective field theory and study the indirect constraints from LFV $\mu$ and $\tau$ decays on the operators that can induce $Z\to \ell_i \ell_j$. We find that, while the $Z\to \mu e$ rates are beyond the expected sensitivities, a Tera Z factory is promising for $Z\to \tau\ell$ decays, probing New Physics at the same level of future low-energy LFV observables. Comment: 31 pages, 5 figures. References added, typos corrected. Matches published version |
| Databáze: | arXiv |
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