Flavour and collider signals from a singly charged scalar

Manzari, C. A. (2021) Flavour and collider signals from a singly charged scalar. Il nuovo cimento C, 44 (6). pp. 1-8. ISSN 1826-9885

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Abstract

A singly charged SU(2)L scalar singlet can only have flavour offdiagonal couplings to neutrinos and charged leptons and therefore necessarily violates lepton flavour (universality) (LF(U)). We study its phenomenology in light of the hints for LFU violation emerging from the measurements of τ → μνν/τ ¯ (μ) → eνν¯ and from the discrepancies between the different determinations of Vus, the so called “Cabibbo-Angle Anomaly”. Interestingly, the singly charged scalar has only three free couplings and is therefore very predictive: it violates LF(U), leads to a positive definite effect in l → l' νν¯ , as preferred by data, and allows us to make predictions for radiative lepton decays and 3-body charged lepton decays. Finally, we look at the collider bounds, recasting ATLAS searches for sleptons and dark matter searches with mono-photon signatures at LEP. Even though these bounds are not yet competitive with flavour bounds, they can be significantly improved at future e+e− colliders. In fact, we find that FCC-hh projections push the predicted value for Br[τ → eμμ] towards the region observable by BELLE II and FCC-ee, providing a prime example of complementarity between low energy precision experiments and direct searches for NP

Item Type:	Article
Subjects:	500 Scienze naturali e Matematica > 530 Fisica
Depositing User:	Marina Spanti
Date Deposited:	10 Dec 2021 10:11
Last Modified:	10 Dec 2021 10:11
URI:	http://eprints.bice.rm.cnr.it/id/eprint/21497

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