Lepton Polarization Asymmetries of $H\toγτ^+τ^-$ Decays in Standard Model

Abstract

Recently, CMS and ATLAS collaborations at LHC announced a Higgs like particle with mass near $125$GeV. Regarding this, to explore its intrinsic properties, different observables are needed to be measured precisely at the LHC for various decay channels of the Higgs. In this context, we calculate the final state lepton polarization asymmetries, namely, single lepton polarization asymmetries ($P_i$) and double lepton polarization asymmetries ($P_{ij}$) in the SM for radiative semileptonic Higgs decay $H\toγτ^+τ^-$. In the phenomenological analysis of these lepton polarization asymmetries both tree and loop level diagrams are considered and it is found that these diagrams give important contributions in the evaluation of said asymmetries. Interestingly, it is found that in $P_{ij}$ the tree level diagrams contribute separately, which however, are missing in the calculations of $P_i$ and the lepton forward-backward asymmetries ($A_{FB}$). Similar to the other observables such as the decay rate and the lepton forward-backward asymmetries, the $τ$-lepton polarization asymmetries would be interesting observables. The experimental study of these observables will provide a fertile ground to explore the intrinsic properties of the SM Higgs boson and its dynamics as well as help us to extract the signatures of the possible new physics beyond the SM.