13 research outputs found
Angular distribution and forward-backward asymmetry of the Higgs-boson decay to photon and lepton pair
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.Comment: 9 pages, 4 figures, SVJour3 class; v2: minor changes in text,
references updated and extended, corresponds to journal versio
Contribution of vector resonances to the {\bar B}_d^0 -> {\bar K}^{*0} mu^+ mu^- decay
The fully differential angular distribution for the rare flavor-changing
neutral current decay \bar{B}_d^0 -> \bar{K}^{*0} (-> K- pi+) mu+ mu- is
studied. The emphasis is placed on accurate treatment of the contribution from
the processes \bar{B}_d^0 -> \bar{K}^{*0} (-> K- pi+) V with intermediate
vector resonances V = rho(770), omega(782), phi(1020), J/psi, psi(2S), ...
decaying into the mu+ mu- pair. The dilepton invariant-mass dependence of the
branching ratio, longitudinal polarization fraction f_L of the \bar{K}^{*0}
meson, and forward-backward asymmetry A_{FB} is calculated and compared with
data from Belle, CDF and LHCb. It is shown that inclusion of the resonance
contribution may considerably modify the branching ratio, calculated in the SM
without resonances, even in the invariant-mass region far from the so-called
charmonia cuts applied in the experimental analyses. This conclusion crucially
depends on values of the unknown phases of the B^0 -> K^{*0} J/psi and B^0 ->
K^{*0} psi(2S) decay amplitudes with zero helicity.Comment: 12 pages, 4 figures, SVJour3 style; introduction and discussion
sections extended, references added; version accepted for publication in Eur.
Phys. J. C. arXiv admin note: substantial text overlap with arXiv:1111.409