Higgs decays to gamma l+ l- in the standard model

The radiative Higgs decays h -> gamma l+l- with l=e,mu and tau are analyzed in the standard model using m_h=125 GeV. Both tree and one-loop diagrams for the processes are evaluated. In addition to their decay rates and dilepton invariant mass distributions, we focus on the forward-back asymmetries in these modes. Our calculation shows that the forward-backward asymmetries in h -> gamma e+e- and h -> gamma mu+mu- could be up to 10^{-2} while in the tau+tau- final state, these asymmetries are below 1%. Thus the forward-backward asymmetries in h -> gamma l+l- might be interesting observables in the future precise experiments both to test our understanding of Higgs physics in the standard model and to probe the novel Higgs dynamics in new physics scenarios.