1,589 research outputs found
Radiative Decays of the P-Wave Charmed Mesons
Minor (mainly numerical) corrections.Comment: 12 pages, LaTeX, MZ-TH/92-5
Helicity fractions of W bosons from top quark decays at NNLO in QCD
Decay rates of unpolarized top quarks into longitudinally and transversally
polarized W bosons are calculated to second order in the strong coupling
constant alpha_s. Including the finite bottom quark mass and electroweak
effects, the Standard Model predictions for the W boson helicity fractions are
F_L=0.687(5), F_+=0.0017(1), and F_-=0.311(5).Comment: 5 pages, 1 figur
Semileptonic and nonleptonic decays of Bc
Using our relativistic constituent quark model we present results on the
exclusive nonleptonic and semileptonic decays of the Bc-meson. The nonleptonic
decays are studied in the framework of the factorization approximation. We
calculate the branching ratios for a large set of exclusive nonleptonic and
semileptonic decays of the Bc-meson and compare our results with the results of
other models.Comment: 4 pages, proceeding of the talk given by Pietro Santorelli at IFAE
2006, Pavia, 19-21 Aprile 200
J/\psi dissociation cross sections in a relativistic quark model
We calculate the amplitudes and the cross sections of the charm dissociation
processes J/\psi \pi => D \bar D, D* \bar D, D \bar D*, D* \bar D* within a
relativistic constituent quark model. We consistently account for the
contributions coming from both the box and triangle diagrams that contribute to
the dissociation processes. The cross section is dominated by the D* \bar D and
D* \bar D* channels. When summing up the four channels we find a maximum total
cross section of about 2.3 mb at sqrt(s) \approx 4.1 GeV. We compare our
results to the results of other model calculations.Comment: 22 pages, 9 figures, typos corrected, this version will appear on
Phys. Rev.
Semileptonic decays of Bc mesons into charmonium states in a relativistic quark model
We use the framework of a relativistic constituent quark model to study the
semileptonic transitions of the Bc meson into CCbar charmonium states where
CCbar = etaC (1S0), J/psi (3S1), chiC0 (3P0), chiC1 (3P1), hc (1P1), chiC2
(3P2), psi (3D2). We compute the q^2-dependence of all relevant form factors
and give predictions for their semileptonic Bc decay modes including also their
tau-modes. We derive a formula for the polar angle distribution of the charged
lepton in the (l nu) c.m. frame and compute the partial helicity rates that
multiply the angular factors in the decay distribution. For the discovery
channel [B_c => J/psi (=> mu+ mu-) l nu] we compute the transverse/longitudinal
composition of the J/psi which can be determined by an angular analysis of the
decay J/psi => mu+ mu-. We compare our results with the results of other
calculations.Comment: 16 pages RevTex, this version will appear in Physical Review
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