Hadronic weak decays of heavy mesons and nonfactorization

The parameters L_1,2, which measure nonfactorizable soft gluon contributions to hadronic weak decays of mesons, are updated by extracting them from the data of D,rBMPP,r VP decays (P: pseudoscalar meson, V: vector meson). It is found that L₂ ranges from т.36 to т.60 in the decays from DMK¥? to D⁺MJ?⁺,r DMK¥^*?, while it is of order 10% with a positive sign in BMNK,r D?,r D^*?,r DA decays. Therefore, the effective parameter a₂ is process dependent in charm decay, whereas it stays fairly stable in B decay. This is in accordance with the picture that nonfactorizable soft gluon effects become stronger when the relative momentum of the decay particles becomes smaller. As for D,r BMVV decays, the presence of nonfactorizable terms in general prevents a possible definition of effective a₁ and a₂. This is reinforced by the observation of a large longitudinal polarization fraction in BMNK^* decay, implying nonfactorizable effects contributing differently to S-, Pand D-wave amplitudes. We found that A^nf₁/A₁>0> A^nf₂/A₂,r V^nf/V (nf standing for nonfactorization) for BMNK^* decay and 0>A^nf₁/A₁>A^nf₂/A₂,r V^nf/V for DMK¥^*A decay. A measurement of longitudinally and transversely polarized decay rates &_L and &_T in colorsuppressed decay modes B¥⁰MD^*0A⁰, D^*0P and D⁺M JA⁺ is urged.     

Hadronic weak decays of heavy mesons and nonfactorization

The parametersχ _1,2, which measure nonfactorizable soft gluon contributions to hadronic weak decays of mesons, are updated by extracting them from the data ofD, B→PP, VP decays (P: pseudoscalar meson,V: vector meson). It is found thatχ ₂ ranges from −0.36 to −0.60 in the decays fromD→Kπ toD ⁺→φπ ⁺,D→K*π, while it is of order 10% with a positive sign inB→ψK, Dπ, D*π, Dρ decays. Therefore, the effective parametera ₂ is process dependent in charm decay, whereas it stays fairly stable inB decay. This is in accordance with the picture that nonfactorizable soft gluon effects become stronger when the relative momentum of the decay particles becomes smaller. As forD, B→VV decays, the presence of nonfactorizable terms in general prevents a possible definition of effectivea ₁ anda ₂. This is reinforced by the observation of a large longitudinal polarization fraction inB→ψK* decay, implying nonfactorizable effects contributing differently toS-, P- andD-wave amplitudes. We found thatA ₁ ^nf /A ₁>0>A ₂ ^nf /A ₂,V ^nf/V (nf standing for nonfactorization) forB→ψK* decay and 0>A ₁ ^nf /A ₁>A ₂ ^nf /A ₂,V ^nf/V forD→K*ρ decay. A measurement of longitudinally and transversely polarized decay rates Γ _L and Γ _T in color-suppressed decay modesB ⁰→D*⁰ ρ ⁰,D*⁰ ω andD ⁺→φρ ⁺ is urged.     

Estimating the production rates of D-wave charmed mesons via the semileptonic decays of bottom mesons

Using the covariant light-front approach with conventional vertex functions, we estimate the production rates of D-wave charmed/charmed-strange mesons via the B_((s)) semileptonic decays. As the calculated production rates are significant, it seems possible to experimentally search for D-wave charmed/charmed-strange mesons via semileptonic decays, which may provide an additional approach for exploring D-wave charmed/charmed-strange mesons.     

Asymmetries in heavy meson production from light quark fragmentation

We discuss the possibility of the asymmetry in production from beams, being a direct consequence of the properties of the light quark fragmentation function into heavy mesons. The main features of the asymmetry, as a function of , are easily described. An integrated sum rule for the multiplicity difference is presented. Predictions for the asymmetry in meson production are given. Received: 5 August 1999 / Published online: 17 March 2000     

Radiative decays of heavy mesons with heavy quark symmetry

The radiative decays of heavy mesons are considered in heavy quark symmetry formalism. Introducing the interpolating fields for the heavy mesons we obtain the transition matrix element and the corresponding decay widths in the heavy quark symmetry limits. The Isgur-Wise function present in the expression is determined by ISGW quark model. The results obtained agree reasonably well with other estimations.     

Ds1(2536)+ decays and the structure of P-wave charmed strange mesons

We calculate the D s 1 (2536) + decays into D*K channels,including the decay D s 1 (2536) + → D + π-K + through a virtual D*0 in a constituent quark model.Widths and S/D amplitudes ratio are in agreement with the recent Belle and BABAR data,being the results sensitive to 1 P 1 and 3 P 1 mixture.     

Decay constants of heavy quark mesons in a non-relativistic quark model

The weak decay constants of charm, bottom and top quark pseudoscalar mesons are calculated in a non-relativistic QCD potential model. The decay constants are obtained as ƒ_D > ƒ_B > ƒ_T. An opposite result, ƒ_D < ƒ_B < ƒ_T, is obtained by Mathur et al. using the QCD sum rules. A possible cause of this discrepancy and a comparison of our results with other calculations is presented also.     

Spin dependence of heavy quark fragmentation

We propose that the non-perturbative part of the fragmentation function describing the transition from a heavy quark to a heavy meson is proportional to the square of the produced meson wave function at the origin, taking into account hyperfine interactions. We analyze the effects of this proposal on the number of pseudoscalar mesons compared to the number of vector mesons produced and find a good agreement with experimental data. Finally, we discuss further experimental checks for our hypothesis.     

Radiative leptonic decays of heavy mesons in heavy quark limit

We study the radiative leptonic decays of heavy mesons within the covariant light-front model. Using this model, both the form factors F_V and F_A have the same form when the heavy quark limit is taken. In addition, the relation between the form factor F_V and the decay constant of a heavy meson F_H is obtained. The hadronic parameter β can be determined by the parameters appearing in the wave function of the heavy meson. We find that the value of β is not only quite smaller than the one in the non-relativistic case, but also insensitive to the value of the light quark mass m_q. These results mean that the relativistic effects are very important in this work. We also obtain that the branching ratio of B→lν_lγ is about (1.40–1.67)×10^-6, in agreement with the general estimates in the literature. PACS 12.39.Hg; 13.40.Gp