Charged lepton flavour violation and (g-2)μ in the Littlest Higgs model with T-Parity: A clear distinction from Supersymmetry

Abstract

We calculate the rates for the charged lepton flavour violating decays ℓi→ℓjγ, τ→ℓπ, τ→ℓη, τ→ℓη′, μ -→e-e+e-, the six three body leptonic decays τ-→ℓi-ℓj+ℓk- and the rate for μ-e conversion in nuclei in the Littlest Higgs model with T-parity (LHT). We also calculate the rates for KL,S→μe, K L,S→π0μe and B d,s→ℓiℓj. We find that the relative effects of mirror leptons in these transitions are by many orders of magnitude larger than analogous mirror quark effects in rare K and B decays analyzed recently. In particular, in order to suppress the μ→eγ and μ-→e-e+e- decay rates and the μ-e conversion rate below the experimental upper bounds, the relevant mixing matrix in the mirror lepton sector VHℓ must be rather hierarchical, unless the spectrum of mirror leptons is quasi-degenerate. We find that the pattern of the LFV branching ratios in the LHT model differs significantly from the one encountered in the MSSM, allowing in a transparent manner to distinguish these two models with the help of LFV processes. We also calculate (g-2)μ and find the new contributions to a μ below 110-10 and consequently negligible. We compare our results with those present in the literature. © SISSA 2007.