Strong decays of QQ¯ mesons

Progress of Theoretical Physics Supplement, 2010

We study the decay properties of a heavy-light meson. We reformulate the decay amplitudes for the heavy-light systems and find a new way to calculate decay rates. Applying this formulation, we find a new sum rule for the radiative decays of one heavy-light meson into another, H 1 → H 2 + γ with various combinations of H

Nuclear Physics A, 2010

Here we present the two-photon and two-gluon decay widths of the S-wave (η Q∈c,b) and P-wave (χ Q∈c,bJ) charmonium and bottonium states and the radiative transition decay widths of cc, bb and cb systems based on Coulomb plus power form of the inter-quark potential (CP P ν) with exponent ν. The Schrödinger equation is solved numerically for different choices of the exponent ν. We employ the masses of different states and their radial wave functions obtained from the study to compute the two-photon and two-gluon decay widths and the E1 and M1 radiative transitions. It is found that the quarkonia mass spectra and the E1 transition can be described by the same interquark model potential of the CP P ν with ν = 1.0 for cc and ν = 0.7 for bb systems, while the M1 transition (at which the spin of the system changes) and the decay rates in the annihilation channel of quarkonia are better estimated by a shallow potential with ν < 1.0.

Physical review D: Particles and fields, 1995

We analyse the Lorentz structures of weak decay matrix elements between meson states of arbitrary spin. Simplifications arise in the transition amplitudes for a heavy meson decaying into the light one via a Bethe-Salpeter approach which incorporates heavy quark symmetry. Phenomenological consequences of our results on several semileptonic, nonleptonic and flavour changing neutral current-induced decays of heavy flavoured mesons are derived and discussed.

Physical Review D, 2010

We study in this work the two-body hadronic charmed meson decays, including both the P P and V P modes. The latest experimental data are first analyzed in the diagrammatic approach. The magnitudes and strong phases of the flavor amplitudes are extracted from the Cabibbo-favored (CF) decay modes using χ 2 minimization. The best-fitted values are then used to predict the branching fractions of the singly-Cabibbo-suppressed (SCS) and doubly-Cabibbo-suppressed decay modes in the flavor SU(3) symmetry limit. We observe significant SU(3) breaking effects in some of SCS channels. In the case of V P modes, we point out that the A P and A V amplitudes cannot be completely determined based on currently available data. We conjecture that the quoted experimental results for both D + s →K 0 K * + and D + s → ρ + η ′ are overestimated. We compare the sizes of color-allowed and color-suppressed tree amplitudes extracted from the diagrammatical approach with the effective parameters a 1 and a 2 defined in the factorization approach. The ratio |a 2 /a 1 | is more or less universal among the D →Kπ,K * π andKρ modes. This feature allows us to discriminate between different solutions of topological amplitudes. For the long-standing puzzle about the ratio Γ(D 0 → K + K −)/Γ(D 0 → π + π −), we argue that, in addition to the SU(3) breaking effect in the spectator amplitudes, the long-distance resonant contribution through the nearby resonance f 0 (1710) can naturally explain why D 0 decays more copiously to K + K − than π + π − through the W-exchange topology. This has to do with the dominance of the scalar glueball content of f 0 (1710) and the chiral-suppression effect in the decay of a scalar glueball into two pseudoscalar mesons. The same FSI also explains the occurrence of D 0 → K 0K 0 and its vanishing amplitude when SU(3) flavor symmetry is exact. Owing to the G-parity selection rule, D + s → π + ω does not receive contributions from the short-distance W-annihilation and resonant FSIs, but it can proceed through the weak decays D + s → ρ + η (′) followed by the final-state rescattering of ρ + η (′) into π + ω through quark exchange.

Physical Review D, 2017

We study the phenomenology of two nonets of excited vector mesons, {ρ(1450), K * (1410), ω(1420), φ(1680)} and {ρ(1700), K * (1680), ω(1650), φ(???)}, which (roughly) correspond to radially excited 2 3 S1 and to orbitally excited 1 3 D1 vector mesons. We evaluate the strong and radiative decays of these mesons into pseudoscalar and ground-state vector mesons by using an effective relativistic QFT model based on flavour symmetry. We compare decay widths and branching ratios with various experimental results listed in the PDG. An overall agreement of theory with experiment reinforces the standard quark-antiquark assignment of the resonances mentioned above. Predictions for not yet measured quantities are also made. In particular, we shall also make predictions for the not-yet discovered ss state of the 1 3 D1 nonet, denoted as φ(???). Its mass can be estimated to be about 1930 MeV, hence we shall call this putative state φ(1930). Its main decays are into KK * (892) (about 200 MeV) and KK (about 100 MeV). Since this state couples also to γη, it can be searched in the near future in the photoproduction-based experiments GlueX and CLAS12 at Jefferson Lab.

Nuclear Physics B - Proceedings Supplements, 2000

We present preliminary results for heavy to light transitions of pseudoscalar mesons, induced by the vector and tensor operators. This lattice study is performed in quenched approximation, by using the nonperturbatively improved Wilson action and operators. We also update the values of the heavy-light meson decay constants.

Assuming Coulomb-like as well as confining scalar potential, we have solved Shrödinger equation perturbatively in 1/m Q with a heavy quark mass m Q . The lowest order equation is examined carefully. Mass levels are fitted with experimental data for D/B mesons at each level of perturbation. Meson wave functions obtained thereby can be used to calculate ordinary form factors as well as Isgur-Wise functions for semileptonic weak decays and other physical quantities. All the above calculations are expanded in 1/m Q order by order to determine parameters as well as to compare with results of Heavy Quark Effective Theory.

Physical Review D, 2015

Inspired by the present experimental status of charmed-strange mesons, we perform a systematic study of the charmed-strange meson family, in which we calculate the mass spectra of the charmed-strange meson family by taking a screening effect into account in the Godfrey-Isgur model and investigate the corresponding strong decays via the quark pair creation model. These phenomenological analyses of charmed-strange mesons not only shed light on the features of the observed charmed-strange states, but also provide important information on future experimental search for the missing higher radial and orbital excitations in the charmed-strange meson family, which will be valuable task in LHCb, forthcoming BelleII and PANDA.

Physical Review D, 1999

Two-body charmless nonleptonic decays of B u and B d mesons are studied within the framework of generalized factorization in which the effective Wilson coefficients c eff i are renormalization-scale and-scheme independent while factorization is applied to the tree-level hadronic matrix elements. Contrary to previous studies, our c eff i do not suffer from gauge and infrared problems. Nonfactorizable effects are parametrized in terms of N eff c (LL) and N eff c (LR), the effective numbers of colors arising from (V − A)(V − A) and (V − A)(V + A) four-quark operators, respectively. Tree and penguin transitions are classified into six different classes. The data of B − → ρ 0 π − and B − → φK − clearly indicate that N eff c (LR) = N eff c (LL): The first measurement of the b → u mode B − → ρ 0 π − and the experimental information on the tree-dominated mode B − → ωπ − all imply that N eff c (LL) is less than 3, whereas the CLEO measurement of B − → φK − shows N eff c (LR) > 3. For given input parameters, the prediction of B(B → η K) is largely improved by setting N eff c (LL) ∼ 2 and N eff c (LR) > N eff c (LL); in particular, the charm content of the η contributes in the right direction. The decay rate of B → φK * is very sensitive to the form-factor ratio A 2 /A 1 ; the absence of B → φK events does not necessarily invalidate the factorization approach. If the branching ratio of B − → ωK − is experimentally found to be significantly larger than that of B − → ρ 0 K − , we argue that inelastic final-state rescattering may account for the disparity between ωK − and ρ 0 K −. By contrast, if B(B − → ρ 0 K −) ∼ B(B − → ωK −) is observed, then W-annihilation and/or spacelike penguins could play a prominent role. The decay modes B 0 d → φπ 0 , φη, φη , φρ 0 , φω, B − → φπ − , φρ − involving a vector meson φ are dominated by electroweak penguins. We show that a unitarity angle γ larger than 90 • is helpful for explaining the π + π − , πK and η K data. The relative magnitudes of tree, QCD penguin and electroweak penguin amplitudes are tabulated for all charmless B → P P, V P, V V decays. Our favored predictions for branching ratios are those for N eff c (LL) ≈ 2 and N eff c (LR) ∼ 5.

Physical Review D, 1999

Two-body charmless nonleptonic decays of the B s meson are studied within the framework of generalized factorization in which factorization is applied to the tree level matrix elements while the effective Wilson coefficients are µ and renormalization scheme independent, and nonfactorizable effects are parametrized in terms of N eff c (LL) and N eff c (LR), the effective numbers of colors arising from (V − A)(V − A) and (V − A)(V + A) four-quark operators, respectively. Branching ratios of B s → P P, P V, V V decays (P : pseudoscalar meson, V : vector meson) are calculated as a function of N eff c (LR) with two different considerations for N eff c (LL): (a) N eff c (LL) being fixed at the value of 2, and (b) N eff c (LL) = N eff c (LR). Tree and penguin transitions are classified into six different classes. We find that (i) the electroweak penguin contributions account for about 85% (for N eff c (LL) = 2) of the decay rates of B s → ηπ, η π, ηρ, η ρ, φπ, φρ, which receive contributions only from tree and electroweak penguin diagrams; a measurement of them will provide a clean determination of the electroweak penguin coefficient a 9 , (ii) electroweak penguin corrections to B s → ωη () , φη, ωφ, K (*) φ, φφ are in general as significant as QCD penguin effects and even play a dominant role; their decay rates depend strongly on N eff c (LR), (iii) the branching ratio of B s → ηη , the analogue of B d → η K, is of order 2 × 10 −5 , which is only slightly larger than that of η η , K * + ρ − , K + K − , K 0 K 0 decay modes, (iv) the contribution from the η charm content is important for B s → η η , but less significant for B s → ηη , and (v) the decay rates for the final states K +(*) K −(*) follow the pattern: