Abstract
The Higgs-boson decay h -> gamma l+ l- for various lepton states l = (e, mu, tau) is analyzed. The differential decay width and forward-backward asymmetry are calculated as functions of the dilepton invariant mass in a model where the Higgs boson interacts with leptons and quarks via a mixture of scalar and pseudoscalar couplings. These couplings are partly constrained from data on the decays to leptons, h -> l+ l-, and quarks h -> q \bar{q} (where q = (c, b)), while the Higgs couplings to the top quark are chosen from the two-photon and two-gluon decay rates. Nonzero values of the forward-backward asymmetry will manifest effects of new physics in the Higgs sector. The decay width and asymmetry integrated over the dilepton invariant mass are also presented.
Highlights
Since the discovery of the Higgs boson [1,2] its decay channels have been extensively studied
In many extensions of the standard model (SM) a more complicated Higgs sector can exist, and some of the Higgs bosons may not have definite CP parity [4,5,6]. This aspect of the Higgs-boson physics is important for clarification of the origin of the CP violation, and possible additional mechanisms beyond the CP violation via the CKM matrix which can contribute to the observed matter–antimatter asymmetry in the Universe [7]
Let us discuss the choice of parameters s f and p f for the Higgs coupling to the fermions in (1)
Summary
Since the discovery of the Higgs boson [1,2] its decay channels have been extensively studied. We remark that in the framework of the SM the FB asymmetry is equal to zero as a consequence of the scalar nature of the Higgs boson This asymmetry can take nonzero values only in models beyond the SM and this observable is sensitive to possible CP violation in the Higgs sector. As for the Higgs interaction with the top quark, the corresponding couplings are chosen from experimental information on the two-photon, h → γ γ , and twogluon, h → gg, decay widths In this model, for the decays h → γ + − we derive the distribution over the angle θ between the momentum of the lepton (in the rest frame of the pair + −) and momentum of the photon (in the rest frame of h). In Appendix A the loop integrals are defined, and in Appendix B vanishing of the contribution from axial-vector Z f fcoupling to the fermion-loop diagrams is shown
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