Berthold Stech

Exclusive semileptonic decays of heavy mesons

AbstractExclusive 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

Weak form factors for heavy meson decays: An update

\bar B^0 \to \pi ^ + \pi ^ -

Quark-lepton symmetry and mass scales in an E6 unified gauge model

and

Exclusive D-decays

\bar B^0 \to D^{* + } + \pi ^ -

Diquarks, {QCD} Sum Rules and Weak Decays

we find for the corresponding Kobayashi-Maskawa matrix element ratio the limit |Vub/Vcb|≲0.3.

Form factor relations for heavy-to-light transitions☆

AbstractRecent experimental results onD-,Ds- andB-decays are interpreted on the basis of the valence quark model. For nonleptonic decays generally good results are obtained using factorization with little direct annihilation. Final state interaction causes corrections, however: small bare amplitudes can be fed by stronger amplitudes through channel mixing. This effect can simulate or enhance weak annihilation processes in particular if high lying resonances contribute. A comparison of