Two-body nonleptonic decays ofD mesons

The amplitudes for two-body Cabibbo allowed nonleptonic decays ofD mesons are evaluated within the factorization approximation from the effective Hamiltonian including short distance QCD corrections to next-to-leading order. Annihilation andW-exchange contributions as well as final state interaction effects have been included and are in fact crucial to obtain agreement with the experimental data.     

Soft-gluon effects in nonleptonic decays of charmed mesons

Soft-gluon effects in nonleptonic decays of D and F mesons are studied nonperturbatively by use of a QCD multipole expansion. For reasonable values of D-meson bound-state parameters, the soft-gluon effects lead to a significant difference in the lifetimes of the D⁰ and D⁺ mesons.     

Improved measurement of Vub with inclusive semileptonic B decays

We report a new measurement of the Cabibbo-Kobayashi-Maskawa parameter Vub made with a sample of 9.7 x 10(6) BB- events collected with the CLEO II detector. Using heavy quark theory, we combine the observed yield of leptons from semileptonic B decay in the end-point momentum interval 2.2-2.6 GeV/c with recent CLEO II data on B-->X(s)gamma to find Vub = (4.08+/-0.34+/-0.44+/-0.16+/-0.24)x10(-3), where the first two uncertainties are experimental and the last two are from theory.     

The surprising nonleptonic decays

Recent experiments onD-meson decays necessitate a revision of the standard theoretical model for weak decays. In this paper we argue that the presence of gluons in hadrons as required by local color gauge-invariance of Quantum Chromodynamics vitiates, in particular, two assumptions previously made:

1. color suppression factors in amplitudes for weak decays like \(D^0 \to \bar K^0 \pi ^0 \) ,
2. helicity suppression of two-quark interactions in weak decays.

A formula for estimating inclusive rates of mesons decaying via two-quark interactions is derived. Estimates for decay rates and branching ratios of several interesting decays of charmed hadrons are given. In particular, we obtain lifetime estimates forD ⁰,D ⁺, andF ⁺, and we predict the branching ratio for Cabibbo-suppressed decays ofD ⁺ to be of order 0.3 rather than of order tan²Θ _c as expected within the conventional model for weak decays.B-meson decays, which would provide an additional test of our scheme, are briefly discussed. Furthermore we point out that our approach sheds new light on the old problem of strongly enhanced |ΔI|=1/2 amplitudes in nonleptonic decays of strange particles.     

Inclusive semileptonic decays of B mesons

The probability of inclusive semileptonic decay of B mesons is calculated in the constituent-quark model. A compact formula is obtained for the differential decay width of a B meson in terms of the corresponding decay width of a free b quark and the wave function of the internal motion of the quarks in the B meson. Numerical values of semileptonic-decay widths are obtained for a series of models of the wave function. Pis’ma Zh. éksp. Teor. Fiz. 65, No. 10, 734–737 (25 May 1997)