Bounds on LFV Higgs decays in a vector-like lepton model and searching for doubly charged leptons at the LHC

摘要

The Higgs-portal lepton flavor violation is studied in a vector-like lepton model. To avoid the constraints from rare (Z ightarrow ell ^pm _i ell ^mp _j) decays, we introduce two triplet vector-like leptons, ((1,3)_{-1}) and ((1,3)_{0}). The resultant branching ratio for (h ightarrow mu au ) can be up to (10^{-4}) when the constraints from the invisible Z decays are applied. As a result, the signal strength for the ( au au ) channel has a (12~%) deviation from the standard model prediction, while the muon (g-2) is two orders of magnitude smaller than the data, and (mathrm{BR}( au ightarrow mu gamma )) is of the order of (10^{-12}). A predicted doubly charged lepton in pp collisions at (sqrt{s}=13) TeV is analyzed, and it is found that the interesting production channels are (pp ightarrow (Psi ^{-,-}_{1} Psi ^{++}_1, Psi ^{pm pm }_1 Psi ^mp _1)). Both single and pair production cross sections of (Psi ^{++}_1) are comparable, and can be a few hundred fb. The main decay channels for the doubly charged lepton are (Psi ^{pm pm } ightarrow ell ^pm W^pm ), and for the heavy singly charged lepton they are (Psi ^pm _1 ightarrow u W^pm , ell ^pm Z). The numerical analysis is carried out with regard to 13 TeV LHC with 100 fb(^{-1}) luminosity.