Study of exclusive charmless semileptonic B decays and |Vub|

We study semileptonic B decay to the exclusive charmless states pi, rho/omega, eta, and eta;{'} using the 16 fb(-1) CLEO Upsilon(4S) data sample. We find B(B0-->pi-l+nu)=(1.37+/-0.15stat+/-0.11sys)x10(-4) and B(B0-->rho-l+nu)=(2.93+/-0.37stat+/-0.37sys)x10(-4) and find evidence for B+-->eta'l+nu, with B(B+-->eta'l+nu)=(2.66+/-0.80stat+/-0.56sys)x10(-4). From our B-->pilnu rate for q2>16 GeV2 and lattice QCD, we find |Vub|=(3.6+/0.4stat+/0.2syst-0.4thy+0.6)x10(-3) [corrected]     

Observation of charmless B meson decays

Using the ARGUS detector at the e⁺e⁻ storage ring DORIS II, we have observed charmless decays of B mesons into the final states pp̄π^± and pp̄π⁺π⁻. The significance of the signal corresponds to more than five standard deviations. The branching ratios are (5.2±1.4±1.9)×10⁻⁴ for the three-body and (6.0±2.0±2.2)×10⁻⁴ for the four-body final state. These decays cannot proceed via the dominant b→c transitions, and we show that they are not the result of penguin-type processes. Thus, the observed decays must represent b→u quark transitions. Consequently, the Kobayashi-Maskawa matrix element V_ub is non-zero.     

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)     

The inclusive semileptonic B decay lepton spectrum from $$ B \to Xe\bar v$$

In this talk, we review the QCD calculations of the lepton spectrum from inclusive semileptonicB decay. We compare this prediction to that of the ACCMM model. This latter work was done in collaboration with Csaba Csaki.     

CP violation and the absence of second class currents in charmless B decays

The absence of second class currents together with the assumption of the factorization for non-leptonic B decays provide new constraints on CP observables in the decay . The kinematics of this decay does not allow for interference between the oppositely charged resonances in the Dalitz plot as in . Nonetheless, under the assumption of factorization, the two-body time-dependent isospin analysis leads to a more robust extraction of the angle than in the isospin-pentagon analysis. The absence of second class currents might lead to enhanced direct CP violation and/or allows for a test of some assumptions made in the analysis in other decays like , and . The effects from non-factorizable contributions on the determination of are estimated by means of a numerical study. Received: 3 July 2001 / Revised version: 19 September 2001 Published online: 21 November 2001     

Measurement of charge asymmetries in charmless hadronic B meson decays

We search for CP-violating charge asymmetries (alpha(CP)) in the B meson decays to K(+/-)pi(-/+), K(+/-)pi(0), K(0)(S)pi(+/-), K(+/-)eta('), and omega pi(+/-). Using 9.66 million upsilon(4S) decays collected with the CLEO detector, the statistical precision on alpha(CP) is in the range of +/-0.12 to +/-0.25 depending on decay mode. While CP-violating asymmetries of up to +/-0.5 are possible within the standard model, the measured asymmetries are consistent with zero in all five decay modes studied.