Exclusive semileptonic decays of heavy mesons

Exclusive semileptonic decays of heavy mesons provide interesting information on systems consisting of quarks of unequal mass. We express the formfactors of the hadronic current in terms of relativistic bound state wave functions for which we take the solutions of a relativistic harmonic oscillator potential. The wave function overlap is determined by the quark mass dependent longitudinal momentum distribution and differs from results based on non relativistic wave functions. The semileptonic widths and lepton spectra are calculated using in addition nearest pole dominance for the momentum transfer dependence of the formfactors. We compare our results with recent experimental data. The formfactor calculation also allows an estimate of special nonleptonic transitions. From the CLEO results on \(\bar B^0 \to \pi ^ + \pi ^ -\) and \(\bar B^0 \to D^{* + } + \pi ^ -\) we find for the corresponding Kobayashi-Maskawa matrix element ratio the limit |V _ub /V _cb |?0.3.     

Hadroproduction of heavy quark flavors in QCD

Within the framework of perturbative QCD, we investigate the hadroproduction of charmed particles via two-gluon as well as quark-pair annihilation. The total production cross section is found to be sensitive to the choice of the scale parameter Q² and in general not free from non-perturbative effects. Charmed-particle production in the high-p_T region is also studied.     

Rare semileptonic decays of heavy mesons in the heavy quark limit

We study the branching ratios of D+→D0e+ν,DS+→D0e+ν,BS0→B+e-ν,DS+→D+e-e+ and BS0→B0e-e+ rare semileptonic decay processes,which are induced by decays of light quarks,the heavy quarks remain unchanged.The branching ratios of these decay processes are estimated in the heavy quark limit and with SU(3) flavor symmetry.We find that the decay rates are very tiny in the framework of the Standard Model.We also estimate the sensitivities of the measurements of these rare decays at the future experiments,such as BES-Ⅲ,super-B and LHC-b.Observations of these decays may shed some light on new physics beyond the standard model.     

Rare semileptonic decays of heavy mesons in the heavy quark limit

We study the branching ratios of D^＋ → D^0e^＋ν, Ds^＋ → D^0e^＋ν, Bs^0→B^＋e^-^-ν, Ds^＋→D^＋e^-e^＋ and Bs^0→B^0e^-e^＋ rare semileptonic decay processes, which are induced by decays of light quarks, the heavy quarks remain unchanged. The branching ratios of these decay processes are estimated in the heavy quark limit and with SU（3） flavor symmetry. We find that the decay rates are very tiny in the framework of the Standard Model. We also estimate the sensitivities of the measurements of these rare decays at the future experiments, such as BES-Ⅲ, super-B and LHC-b. Observations of these decays may shed some light on new physics beyond the standard model.     

Effects of multiple QCD and QED radiations in semileptonic decays of top particles

The charged lepton spectrum in semileptonic decays of top particles is calculated including the effects of multiple QCD and QED radiations, treated in the leading logarithm approximation. A comparison with QCDO(α _S ) results is made. Nonperturbative effects associated with the hadronization of the decay partons are also discussed. The effects of QED radiation are found to be important. Calculations have been done by means of a Monte Carlo algorithm, which also allows to calculate the full decay final state.     

Exclusive semileptonic heavy meson decays including lepton mass effects

We discuss the exclusive semi-leptonic (s.l.) bottom meson decaysB→D(D ^*)+l+v where we include non-zero lepton mass effects in the kinematics and dynamics. We develop the general formalism for the non-zero lepton mass case. We then look at how rates, spectra and angular correlations are affected by non-zero lepton masses in the context of a specific spectator quark model. Numerical results are presented for s.l. decays involving thee-, μ- and τ-leptons. We also discuss the s.l. decaysB→π(ρ),D→K(K ^*) and the free quark decay model.     

Determination of heavy quark non-perturbative parametersfrom spectral moments in semileptonic B decays

Moments of the hadronic invariant mass and of the lepton energy spectra in semileptonic B decays have been determined with the data recorded by the DELPHI detector at LEP. From measurements of the inclusive b-hadron semileptonic decays, and imposing constraints from other measurements on b- and c-quark masses, the first three moments of the lepton energy distribution and of the hadronic mass distribution, have been used to determine parameters which enter into the extraction of |V_cb| from the measurement of the inclusive b-hadron semileptonic decay width. The values obtained in the kinetic scheme are: and include corrections at order 1/m_b³. Using these results, and present measurements of the inclusive semileptonic decay partial width of b-hadrons at LEP, an accurate determination of |V_cb| is obtained: Received: 26 April 2005, Revised: 16 September 2005, Published online: 16 November 2005     

Meson decays in an extended Nambu-Jona-Lasinio model with heavy quark flavors

In a previous work, we proposed an extended Nmnbu-Jona-Lasinio （NJL） model including heavy quark flavors. In this work, we will calculate strong and radiative decays of vector mesons in this extended NJL model, including light p, w, K＊, θ and heavy D＊, D＊s, B＊, Bs＊.     

Meson decays in an extended Nambu—Jona-Lasinio model with heavy quark flavors

In a previous work,we proposed an extended Nambu-Jona-Lasinio(NJL)model including heavy quark flavors.In this work,we will calculate strong and radiative decays of vector mesons in this extended NJL model,including lightρ,ω,K*,(?)and heavy D~*,D_s~*,B~*,B_s~*.