Nonfactorizable contributions to hadronic decays of charm mesons in the Cabibbo-suppressed modes

We investigate nonfactorizable contributions to charm meson decays into D → ππ/K K?/K K?*/K? K*/D → K*K?* modes. Obtaining the contributions from spectatorquark diagrams for N _c = 3, we determine the nonfactorizable isospin amplitudes required to explain the data for these modes. For these decays, we observe that ππ, πρ, decay modes favor a nonfactorizable-isospin-amplitudes ratio A ₀ ^nf /A ₂ ^nf equal to (1.123±0.158) and for K K?, K K?*, K? K* and K*K?* modes, the ratio of nonfactorizable amplitudes A ₀ ^nf and A ₁ ^nf turns out to be unity.     

Production of P-wave charm and charm-strange mesons in hadronic Z0 decays

Results are presented on the production of excited charm and excited charm-strange mesons in hadronic Z⁰ decays. The results are obtained from approximately 4.3 million hadronic Z⁰ decays, collected on or near the Z⁰ resonance using the OPAL detector at LEP. The D⁰ ₁(2420) and D^*0 ₂ (2460) mesons are reconstructed in the D^*+π^-. final state and their separate production rates in charm fragmentation and in weak decays of b-hadrons are determined. Assuming that the decay widths of these mesons are saturated by the allowed D*π and Dπ final states, the charm hadronization fractions and the inclusive branching ratios of b-hadrons to these neutral P-wave charm mesons are determined to be     

Charmless hadronic decays of B mesons to a pseudoscalar and a tensor meson

We study two-body charmless hadronic decays of B mesons to a pseudoscalar meson (P) and a tensor meson (T) in the frameworks of both flavor SU(3) symmetry and generalized factorization. Certain ways to test the validity of the generalized factorization are proposed, based on the flavor SU(3) analysis. We present a set of relations between a flavor SU(3) amplitude and the corresponding amplitude in the generalized factorization which bridge both approaches in decays. The branching ratios and CP asymmetries are calculated using the full effective Hamiltonian including all the penguin operators and the form factors obtained in the non-relativistic quark model of Isgur, Scora, Grinstein and Wise. We identify the decay modes in which the branching ratios and CP asymmetries are expected to be relatively large. Received: 6 July 2001 / Revised version: 8 October 2001 / Published online: 30 November 2001     

CP violation in two-body hadronic decays of B_c mesons

Using the next-to-leading-order low-energy effective Hamiltonian, the CP asymmetries for -meson decays into meson pairs are calculated in the spectator approximation. We do not compute the hadronic matrix elements directly; instead, we use the amplitude ratios to estimate the CP asymmetries. This is quite different from previous treatments in the literature. The values of the momentum squared carried by the virtual particles in timelike penguin diagrams are also carefully discussed. From our calculated results, the best decay modes to observe CP violation in decays would be , , , , and , each of them needs about of events in experiment. Received: 17 December 1998 / Published online: 30 June 1999     

Inclusive production of neutral vector mesons in hadronic Z decays

A data sample of about 3.0 million hadronicZ decays collected by the ALEPH experiment at LEP in the years 1991 through 1994 is used to make an inclusive selection of B hadron events. In this event sample 4227±140±252B* mesons in the decayB*→Bγ and 1944±108±161B** _u,d mesons decaying into a B meson and a charged pion are reconstructed. Here and in the followingB** _u,d denotes the eightL=1(bū) and (bd) states and their charge conjugate. For the well establishedB* meson the following quantities are obtained:ΔM=M _B*−M_B=(45.30±0.35±0.87) MeV/c² andN _B*/(N _B+N _B*)=(77.1±2.6±7.0)%. The angular distribution of the photons in theB* rest frame is used to measure the relative contribution of longitudinalB* polarization states to beσ _L/(σ _L+σ _T)=(33±6±5)%.     

Pole contributions in semileptonic decays of D mesons

The contributions of the axial-vector and vector resonance states to D → P(V)l $\bar \nu$ _l decays are investigated on the basis of phenomenological chiral Lagrangians. It is shown that inclusion of such intermediate states improves agreement with experimental data.     

Towards a quantitative description of hadronic weak decays: Evolution equations for heavy flavour mesons

We develop a formalism for describing hadronic weak annihilation decays in analogy to the treatment of deep inelastic lepton-nucleon scattering: we write down evolution equations for colour singlet and octet $\text{(}\text{Q}\text{q}\text{)}$ systems inside mesons of increasing mass. Using D decays as input we can predict weak annihilation decay rates of heavier mesons in a semiquantitative fashion despite our ignorance on bound-state dynamics.     

Spin effects in two-body hadronic decays of the B c mesons

Spin effects in the weak two-body hadronic decays of the B _c and B _c ^* mesons into J/ψ and ρ(π) mesons are considered within the model of hard one-gluon exchange between quarks at high momentum transfers. It is shown that the polarization of the J/ψ meson in the decays of the B _c ^* meson differs substantially from that in the decays of the B _c ^* meson. The decay widths of the B _c ^* meson differ significantly from the widths of the B _c ^* meson.     

Searches for B0 decays to combinations of two charmless isoscalar mesons

We search for B meson decays into two-body combinations of eta, eta', omega, and phi mesons from 89 x 10(6) BB pairs collected with the BABAR detector at the PEP-II asymmetric-energy e+e- collider at SLAC. We find the branching fraction B(B0-->etaomega)=(4.0(+1.3)(-1.2)+/-0.4)x10(-6) with a significance of 4.3 sigma. For the other decay modes we set the following 90% confidence level upper limits on the branching fractions, in units of 10(-6): B(B0-->etaeta)<2.8, B(B0-->etaeta')<4.6, B(B0-->eta'eta')<10, B(B0-->eta'omega)<2.8, B(B0-->etaphi)<1.0, B(B0-->eta'phi)<4.5, and B(B0-->phiphi)<1.5.     

Measurement of inclusive π0 production in hadronic Z 0 decays

An analysis is presented of inclusive π⁰ production in Z ⁰ decays measured with the DELPHI detector. At low energies, π⁰ decays are reconstructed by using pairs of converted photons and combinations of converted photons and photons reconstructed in the barrel electromagnetic calorimeter (HPC). At high energies (up to $x_p={2cdot p?/{sqrt s}=0.75}$) the excellent granularity of the HPC is exploited to search for two-photon substructures in single showers. The inclusive differential cross section is measured as a function of energy for qq? and bb? events. The number of π⁰’s per hadronic Z ⁰ event is $N(?^0)/Z_{had} ^0=9.2pm 0.2({? stat})pm 1.0 ({? syst})$ and for bb? events the number of π⁰’s is ${? N}(?^0)/{? b?r b}=10.1pm 0.4({? stat})pm 1.1 ({? syst})$. The ratio of the number of π⁰’s in bb? events to hadronic Z ⁰ events is less affected by the systematic errors and is found to be 1.09 ±0.05 ±0.01. The measured π⁰ cross sections are compared with the predictions of different parton shower models. For hadronic events, the peak position in the $xi_{? p}={? ln}(1/{? x_p})$ distribution is $xi_p^{?ar}=3.90_{-0.14}^{+0.24}.$ The average number of π⁰’s from the decay of primary B hadrons is found to be N(B → π⁰ X)/B hadron = 2.78 ± 0.15(stat) ± 0.60(syst).     

Measurement of B0-B-0 flavor oscillations in hadronic B0 decays

Flavor oscillations of neutral B mesons have been studied in e+e- annihilation data collected with the BABAR detector at center-of-mass energies near the upsilon(4S) resonance. The data sample used for this purpose consists of events in which one B0 meson is reconstructed in a hadronic decay mode, while the flavor of the recoiling B0 is determined with a tagging algorithm that exploits the correlation between the flavor of the heavy quark and the charges of its decay products. From the time development of the observed mixed and unmixed final states, we determine the B0-B-0 oscillation frequency deltamd to be 0.516+/-0.016(stat)+/-0.010(syst) ps-1.