In this work we assess the potential of discovering new physics by searching for lepton-flavour-violating (LFV) decays of the Z boson, Z→ ℓiℓj, 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 O(10 12) 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 μ and τ decays on the operators that can induce Z→ ℓiℓj. We find that, while the Z→ μe rates are beyond the expected sensitivities, a Tera Z factory is promising for Z→ τℓ decays, probing New Physics at the same level of future low-energy LFV observables.
Calibbi, L., Marcano, X., Roy, J. (2021). Z lepton flavour violation as a probe for new physics at future $$e^+e^-$$ colliders. EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS, 81(12), 1054-1071 [10.1140/epjc/s10052-021-09777-3].
Z lepton flavour violation as a probe for new physics at future $$e^+e^-$$ colliders
Xabier Marcano;
2021
Abstract
In this work we assess the potential of discovering new physics by searching for lepton-flavour-violating (LFV) decays of the Z boson, Z→ ℓiℓj, 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 O(10 12) 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 μ and τ decays on the operators that can induce Z→ ℓiℓj. We find that, while the Z→ μe rates are beyond the expected sensitivities, a Tera Z factory is promising for Z→ τℓ decays, probing New Physics at the same level of future low-energy LFV observables.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
