We analyze the semileptonic $D_{q}\to K_1 \ellν$ transition with $q=u, d, s$, in the framework of the three--point QCD sum rules and the nonleptonic $D\to K_1 π$ decay within the QCD factorization approach. We study $D_{q}$ to $K_1(1270)$ and $K_1(1400)$ transition form factors by separating the mixture of the $K_1(1270)$ and $K_1(1400)$ states. Using the transition form factors of the $D\to K_1 $, we analyze the nonleptonic $D\to K_1 π$ decay. We also present the decay amplitude and decay width of these decays in terms of the transition form factors. The branching ratios of these channel modes are also calculated at different values of the mixing angle $θ_{K_1}$ and compared with the existing experimental data for the nonleptonic case.
Using our relativistic constituent quark model we present results on the exclusive nonleptonic and semileptonic decays of the Bc-meson. The nonleptonic decays are studied in the framework of the factorization approximation. We calculate the branching ratios for a large set of exclusive nonleptonic and semileptonic decays of the Bc-meson and compare our results with the results of other models.
We investigate the semileptonic and nonleptonic decays of $B_s$ mesons. We work within the context of nonrelativistic constituent quark models. We calculate the different form factors that parameterize the hadron matrix elements.
We analyze charm meson semileptonic $D \to V l ν_l$ and $D\to P l ν_l$ and nonleptonic $D \to P V$, $D \to PP$ and $D \to VV$ decays within a model which combines the heavy quark effective Lagrangian and chiral perturbation theory.
We present a brief discussion about expressions of decay widths of exclusive nonleptonic and semileptonic B decays at tree level including $l=0$ and $l=1$ mesons in final state. Our analysis is carried out assuming factorization hypothesis and using parametrizations of hadronic matrix elements given in WSB and ISGW quark models. Special interest is focused on dynamics of these processes and several important ratios between decay widths to determine form factors and decay constants are given.
We study exclusive nonleptonic and semileptonic decays of the Bc-meson within a relativistic constituent quark model previously developed by us. For the nonleptonic decays we use the factorizing approximation. We update our model parameters by using new experimental data for the mass and the lifetime of the Bc meson and the leptonic decay constants of the D-meson. We calculate the branching ratios for a large set of exclusive nonleptonic and semileptonic decays of the $B_c$ meson and compare our results with the results of other studies. As a guide for further experimental exploration we provi…
We evaluate semileptonic and two--meson nonleptonic decays of the $B_c^-$ meson in the framework of a nonrelativistic quark model. The former are done in spectator approximation using one--body current operators at the quark level. Our model reproduces the constraints of heavy quark spin symmetry obtained in the limit of infinite heavy quark mass. For the two--meson nonleptonic decays we work in factorization approximation. We compare our results to the ones obtained in different relativistic approaches.
We calculate the radiative corrections to the nonleptonic inclusive B decay mode $b\to c ud$ taking into account the charm quark mass. The corrections increase the decay rate by (4--8)\%, depending on the renormalization point. Using these results, we obtain an improved theoretical prediction for the semileptonic branching ratio of B mesons. This talk relies on work done in collaboration with E. Bagan, V.M.\ Braun and P. Gosdzinsky.
Form factors of $D$ decays into $J^{PC}=2^{++}$ tensor mesons are calculated in the light-cone sum rules approach up to twist-4 distribution amplitudes of the tensor meson. The masses of the tensor mesons are comparable to that of the charm quark mass $m_c$; therefore all terms including powers of $m_T/m_c$ are kept out in the expansion of the two-particle distribution amplitude $\langle T|\bar q_{1α}(x) \, q_{2δ}(0)|0\rangle$. Branching ratios of the semileptonic $D \to T\,μ\,\barν_μ$ decays and nonleptonic $D\to T~ P ~(P=K, π)$ decays are taken into consideration. A comparison is also made b…
We calculate the semileptonic and a subclass of sixteen nonleptonic two-body decays of the double charm baryon ground states $Ξ_{cc}^{++},\,Ξ_{cc}^{+}$ and $Ω_{cc}^+$ where we concentrate on the nonleptonic decay modes. We identify those nonleptonic decay channels in which the decay proceeds solely via the factorizing contribution precluding a contamination from $W$-exchange. We use the covariant confined quark model previously developed by us to calculate the various helicity amplitudes which describe the dynamics of the $1/2^+ \to 1/2^+$ and $1/2^+ \to 3/2^+$ transitions induced by the Cabib…
We evaluate the form factors describing the semileptonic decays $\bar{B^0}\to J/ψ(η_c) D^+ \ell^- \bar ν_\ell$, within the framework of a QCD relativistic potential model. This decay is complementary to $\bar{B^0}\to J/ψ(η_c) D^+ π^-$ in a phase space region where a pion factors out.We estimate the branching ratio for these semileptonic and nonleptonic channels, finding $\mathcal{BR}(\bar{B^0} \to J/ψ(η_c) D^+ \ell ν_\ell) \simeq 10^{-13}$, $\mathcal{BR}(\bar{B^0} \to J/ψD^+ π^-) = 3.1 \times 10^{-8}$ and $\mathcal{BR}(\bar{B^0} \to η_c D^+ π^-) = 3.5 \times 10^{-8}$.
We analyze $D \to P V$, $D \to PP$ and $D \to VV$ decays within a model developed to describe the semileptonic decays $D \to V l ν_l$ and $D\to P l ν_l$. This model combines the heavy quark effective Lagrangian and chiral perturbation theory. We determine amplitudes for decays in which the direct weak annihilation of the initial $D$ meson is absent or negligible, and in which the final state interactions are small. This analysis reduces the arbitrariness in the choice of model parameters. The calculated decay widths are in good agreement with the experimental results.
We compute important ratios between decay widths of some exclusive two-body nonleptonic and semileptonic B decays, which could be test of factorization hy- pothesis. We also present a summary of the expressions of the decay widths and differential decay rates of these decays, at tree level, including l = 0 (ground state), l = 1 (orbitally excited) and n = 2 (radially excited) mesons in the fi- nal state. From a general point of view, we consider eight transitions, namely H \rightarrow P, V, S, A, A, T, P (2S), V (2S). Our analysis is carried out assuming factorization hypothesis and using the …
In this contribution we compute some nonleptonic and semileptonic decay widths of $B_s$ mesons, working in the context of constituent quark models \cite{Albertus:2014gba, Albertus:2014bfa}. For the case of semileptonic decays we consider reactions leading to kaons or different $J^π$ $D_s$ mesons. The study of nonleptonic decays has been done in the factorisation approximation and includes the final states enclosed in Table 2.
In this work, the transition form factors are calculated for the semileptonic $D_{(s)} \to A \ell^+ ν$ where $A=a_{1}, b_{1}, K_{1}(1270,1400)$, i.e., $D^{+} \to a^{0}_{1} (b^{0}_{1}, K^{0}_{1}) \ell^+ ν$, $D^{0} \to a^{-}_{1} (b^{-}_{1}) \ell^+ ν$, and $D^{+}_{s}\to K^{0}_{1} \ell^+ ν$ in the frame work of the light-cone QCD sum rules (LCSR) approach up to the twist-3 distribution amplitudes (DAs). Since the masses of these axial vector mesons are comparable to the charm quark mass, we keep out in our calculations all terms including ${m_{A}}/{m_c}$ in expansion of two--parton DAs. Branching …
We provide new values for the model parameters of the covariant constituent quark model (with built--in infrared confinement) in the meson sector by a fit to the leptonic decay constants and a number of electromagnetic decays. We then evaluate, in a parameter free way, the form factors of the $B(B_s)\to P(V)$-transitions in the full kinematical region of momentum transfer. As an application of our results we calculate the widths of the nonleptonic $B_s$-decays into $D_s^- D_s^+,$ $D_s^{\ast\,-} D_s^{+}+D_s^- D_s^{\ast\,+}$ and $D_s^{\ast\,-} D_s^{\ast\,+}$. These modes give the largest contrib…
I review some of the recent developments in the theoretical description of weak inclusive decays of heavy mesons. The topics cover the value of $|V_{cb}|$ as extracted from semileptonic inclusive decays and a short discussion of the theoretical errors. I also present the results of a recent calculation of next--to--leading order corrections to nonleptonic inclusive B decays which allows an improved prediction of the semileptonic branching ratio of B mesons.
We propose a number of tests of factorization for the color-suppressed nonleptonic decay channels: $B \to K^{(*)} \; η_c$ and $B \to K^{(*)} \; η^\prime_c$. The relevant leptonic constants and form factors are calculated within the QCD sum rules approach.
We calculate the two-body nonleptonic B decays using the factorization method. The recent measured decays by CLEO Collaboration can be explained in the factorization approach. We propose a number of ratios of branching ratios to determine the effective coefficients and the form factors.
I consider nonleptonic decays of B mesons into two light mesons using the light-cone wave functions for the mesons. In the heavy quark limit, nonfactorizable contributions are calculable from first principles in some decay modes. I review the idea of the QCD-improved factorization method and discuss the implications in phenomenology.
We compare the factorization approach, the perturbative QCD approach and the Beneke-Buchalla-Neubert-Sachrajda approach to nonleptonic charmless $B$ meson decays. We discuss their treatments of factorizable, nonfactorizable, and annihilation contributions, infrared-cutoff and scale dependences, and strong phases. It is proposed that measurement of CP asymmetries in two-body $B$ meson decays provides an appropriate test of the these approaches.
The form factors of weak decays of the B meson to orbitally excited scalar, axial vector and tensor light mesons are calculated in the framework of the QCD-motivated relativistic quark model based on the quasipotential approach. Relativistic effects are systematically taken into account. The form factors are expressed trough the overlap integrals of the meson wave functions and their dependence on the momentum transfer is selfconsistently determined in the whole kinematical range. On this basis semileptonic and two-body nonleptonic B decay rates to orbitally excited light mesons are calculated…
Exclusive semileptonic and nonleptonic $J/ψ$ decays
Federal Research Center “Computer Science and Control” Russian Academy of Sciences（俄罗斯科学院计算机科学与控制中心）；Faculty of Physics, Lomonosov Moscow State University（莫斯科国立大学物理系）
The form factors of weak decays of the B_c meson to orbitally excited charmonium, D, B_s and B mesons are calculated in the framework of the QCD-motivated relativistic quark model based on the quasipotential approach. Relativistic effects are systematically taken into account. The form factor dependence on the momentum transfer is reliably determined in the whole kinematical range. The form factors are expressed trough the overlap integrals of the meson wave functions which are known from the previous mass spectra calculations within the same model. On this basis semileptonic and nonleptonic B…
We suggest that, similar to the many applications of chiral effective Lagrangian made recently to semileptonic decays of heavy hadrons involving Goldstone bosons, chiral symmetry can also be applied to many-body nonleptonic decays of heavy hadrons. As examples we establish the chiral effective Hamiltonian for some typical many-body nonleptonic decays of bottom hadrons. We discuss the lowest-order contributions coming from such a Hamiltonian. We emphasize that wide applications of this method are possible.
We present results for different observables measured in semileptonic and non-leptonic decays of the $B_c^-$ meson. The calculations have been done within the framework of a nonrelativistic constituent quark model. In order to check the sensitivity of all our results against the inter-quark interaction we use five different quark--quark potentials. We obtain form factors, decay widths and asymmetry parameters for semileptonic $B_c^-\to c\bar c$ and $B_c^-\to \bar B$ decays. In the limit of infinite heavy quark mass our model reproduces the constraints of heavy quark spin symmetry. For the actu…
We reconsider the conflict between recent calculations of the semileptonic branching ratio of the $B$ meson and the experimentally measured rate. Such calculations depend crucially on the application of ``local duality'' in nonleptonic decays, and we discuss the relation of this assumption to the weaker assumptions required to compute the semileptonic decay rate. We suggest that the discrepancy between theory and experiment might be due to the channel with two charm quarks in the final state, either because of a small value for $m_c$ or because of a failure of local duality. We examine the exp…
The nonleptonic heavy meson decays $B\to D^{(*)}π(ρ), J/ψK^{(*)}$ and $D\to K^{(*)}π$ are studied based on the three-scale perturbative QCD factorization theorem developed recently. In this formalism the Bauer-Stech-Wirbel parameters a_1 and a_2 are treated as the Wilson coefficients, whose evolution from the W boson mass down to the characteristic scale of the decay processes is determined by effective field theory. The evolution from the characteristic scale to a lower hadronic scale is formulated by the Sudakov resummation. The scale-setting ambiguity, which exists in the conventional appro…
We explore the semileptonic and nonleptonic decays of doubly heavy baryons $(Ω_{cc}^ {(*) +}, Ω_{bb}^ {(*)0}, Ω_{bc}^ {(*) -}, Ω_{bc}^ {\prime 0}) $ induced by the $s\to u$ transition. Hadronic form factors are parametrized by transition matrix elements and are calculated in the light front quark model. With the form factors, we make use of helicity amplitudes and analyze semileptonic and nonleptonic decay modes of doubly heavy baryons. Benchmark results for partial decay widths, branching fractions, forward-backward asymmetries and other phenomenological observables are derived. We find that …
The semileptonic decays and two-body nonleptonic decays of light baryon octet ($T_8$) and decuplet ($T_{10}$) consisting of light $u,d,s$ quarks are studied with the SU(3) flavor symmetry in this work. We obtain the amplitude relations between different decay modes by the SU(3) irreducible representation approach, and then predict relevant branching ratios by present experimental data within $1 σ$ error. We find that the predictions for all branching ratios except $\mathcal{B}(Ξ\rightarrow Λ^0π)$ and $\mathcal{B}(Ξ^*\rightarrow Ξπ)$ are in good agreement with present experimental data, that im…
The semileptonic decays $B_c^+\rightarrow P(V) +\ell^++\barν_\ell$ and the nonleptonic decays $B_c^+\rightarrow P(V)+L$, where $P(V)$ denotes a pseudoscalar (vector) charmonium or ($\bar{b}s$)-meson, and $L$ denotes a light meson, are studied in the framework of improved instantaneous Bethe-Salpeter (BS) equation and the Mandelstam formula. The numerical results (width and branching ratio of the decays) are presented in tables, and in order to compare conveniently, those obtained by other approaches are also put in the relevant tables. Based on the fact that the ratio $\frac{\mathcal{BR}(B_c^+…
We show in a model independent way the equality of the branching fractions and strong phases for B-> D_1M and B-> D_2^*M at leading order in Lambda _{QCD}/Q and alpha_s(Q) where Q={m_b,m_c,E_M} and M is a light meson. These results apply in the color allowed and color suppressed channels and follow from a factorization theorem in SCET combined with heavy quark symmetry. The expected heavy quark symmetry suppression of leading order contributions in the color allowed sector based on analysis of semileptonic decays, is shown to disappear at maximum recoil. Subleading corrections are suppressed b…
The analysis of singly charmed hadrons has been extended to the case of doubly charmed baryons, $Ξ_{cc}^{++}$, $Ξ_{cc}^{+}$ and $Ω_{cc}^{+}$. Doubly charmed baryons are described as a system containing a heavy $cc$-diquark and a light quark, similarly as in a heavy-light meson. This leads to preasymptotic effects in semileptonic and nonleptonic decays which are essentially proportional to the meson wave function. Interplay between preasymptotic effects in semileptonic and/or nonleptonic decay rates leads to very clear predictions for semileptonic branching ratios and lifetimes of doubly charme…
Assuming so called global duality we argue that it is very likely that local duality needed to obtain results for the hadronic width of heavy meson decays within the $1/m_Q$ expansion holds. Hence, if the discrepancy between experiment and the theory concerning charm counting, the semileptonic branching fraction and the lifetimes of $b$ hadrons persist, it may be taken as a hint at some qualitatively new effect in (nonperturbative) QCD or even as a new physics.
The semileptonic and nonleptonic decays of the double-beauty axial-vector tetraquark $T_{bb;\overline{u} \overline{d}}^{-}$ to a state $\widetilde{T}_{bc; \overline{u}\overline{d}}^{0}$ (hereafter $T_{bb}^{-}$ and $\widetilde{T} _{bc}^{0}$, respectively) are investigated in the context of the QCD sum rule method. The final-state tetraquark $\widetilde{T}_{bc}^{0}$ is treated as an axial-vector particle built of a heavy axial-vector diquark $ b^{T}γ_{μ}Cc$ and light scalar antidiquark $\overline{u}Cγ_{5} \overline{d}^{T}$. Its spectroscopic parameters are calculated using the two-points sum rul…
I discuss the recent controversy over the semileptonic branching ratio of the $B$ meson, pointing out that it is only the combination of this quantity with the reported charm multiplicity in $B$ decays which is in serious conflict with theoretical calculations. I consider possible solutions to the problem. (Invited talk presented at the Eighteenth Johns Hopkins Workshop on Current Problems in Particle Theory, Florence, Italy, August 31--September 2, 1994.)
We calculate the radiative corrections to the nonleptonic inclusive B decay mode $b\rightarrow c\bar u d$ taking into account the charm quark mass. Compared to the massless case, corrections resulting from a nonvanishing c quark mass increase the nonleptonic rate by (4--8)\%, depending on the renormalization point. As a by--product of our calculation, we obtain an analytic expression for the radiative correction to the semileptonic decay $b\rightarrow uτ\barν$ taking into account the $τ$ lepton mass, and estimate the c quark mass effects on the nonleptonic decay mode $b\rightarrow c\bar c s$.
In the large $N_c$ limit, the nonleptonic width of the B meson is determined by the lepton mass spectrum in semileptonic B decay and the hadron mass spectrum in $τ$ decay. This result can be compared with the nonleptonic width computed using the operator product expansion and local duality, to estimate the violation of local duality in B decay. In the absence of the required data, we use experimental Monte Carlo predictions and find that the difference is small, at the few percent level. We estimate the theoretical uncertainty in our results from higher order corrections (including $1/N_c$ eff…
We investigate the double logarithmic corrections $α_s\ln^2 x$, x being a parton momentum fraction, in two-body nonleptonic B meson decays in collinear factorization theorem of perturbative QCD (PQCD). It is found that these corrections are universal for factorizable amplitudes, {\it i.e.}, at the leading power, and that their threshold resummation smears the end-point singularities from $x\to 0$. The double logarithmic corrections, depending on the topologies of nonfactorizable amplitudes at the subleading power, are negligible due to the color-transparency argument and to the overlap of thre…
We review selected topics in the field of nonleptonic and rare B meson decays. We concentrate in particular on exclusive channels, discussing recent developments based on the concepts of factorization in QCD and the heavy-quark limit.
We study in a quark model the contradiction between factorization and duality found in nonleptonic decays at next to leading order in $1/N_c$, concentrating on quark exchange mechanism. The contradiction originates in the fact that the standard factorization assumption approximates the asymptotic final states by a non-orthogonal set of states, thus leading to an overcounting of the decay probability. We consider a system with two heavy quarks treated as classical color sources with constant velocity, and two mass-degenerate antiquarks. Exploiting permutation symmetry in an adiabatic approximat…
A selfconsistent treatment of nonperturbative effects in inclusive nonleptonic and semileptonic decays of beauty and charm hadrons is presented. It is illustrated by calculating semileptonic branching ratios, lifetime ratios, radiative decay rates and the lepton spectra in semileptonic decays.
We investigate the nonleptonic decay of charmed meson into two pseudoscalar mesons using the vector--dominance model, and compare the results with those obtained from the factorization model. In particular, we discuss the role of the annihilation diagrams in the two models.
In this paper, with the framework of (p)NRQCD and SCET, the processes $B_c\to M_1 M_2$ are investigated. Here $M_{1(2)}$ denotes the light charmless meson, such as $π$, $ρ$, $K$ or $K^*$. Based on the SCET power counting rules, the leading transition amplitudes are picked out, which include $A_{wA}^2$, $A_{wB}^2$, $A_{wC}^2$, $A_{wD}^2$ and $A_{c}^0$. From SCET, their factorization formulae are proven. Based on the obtained factorization formulae, in particular, the numerical calculation on $A_{wB}^2$ is performed.
We consider possibilities to determine the handedness of $b \ra c$ current transitions using semileptonic baryonic $Λ_{b} \rightarrow Λ_{c}$ transitions. We propose to analyze the longitudinal polarization of the daughter baryon $Λ_c$ by using momentum-spin correlation measurements in the form of forward-backward (FB) asymmetry measures involving its nonleptonic decay products. We use an explicit form factor model to determine the longitudinal polarization of the $Λ_c$ in the semileptonic decay $Λ_b \ra Λ_c + l^- + \bar ν_l$. The mean longitudinal polarization of the $Λ_c$ is negative (positiv…
This talk consists of two parts. We first present a light-cone QCD sum rule computation of the $B_s\to f_0(980)$ form factors which are necessary inputs in semileptonic and nonleptonic $B_s$ decays into $f_0(980)$. Then we analyze nonleptonic $B_s$ decays into a charmonium state and a light meson, which are potentially useful to access the $B_s$-${\bar B}_s$ mixing phase $β_s$. We explore the experimental feasibility of measuring these various channels, paying attention to different determinations of $β_s$ in view of the hints of new physics recently emerged in the $B_s$ sector.
The energetic exclusive two-body nonleptonic decays of B mesons are investigated in the framework of the relativistic quark model within the factorization approximation. The heavy quark expansion is used for the calculation of form factors. The obtained results are in agrement with available experimental data.
The generating functional for Green functions of quark currents is given in closed form to next-to-leading order in the low-energy expansion for chiral SU(3), including one-loop amplitudes with up to three meson propagators. Matrix elements and form factors for strong and nonleptonic weak processes with at most six external states can be extracted from this functional by performing three-dimensional flavour traces. To implement this procedure, a Mathematica program is provided that evaluates amplitudes with at most six external mesons, photons (real or virtual) and virtual W (semileptonic form…
A brief survey of applications of chiral perturbation theory to both semileptonic and nonleptonic kaon decays is presented. Special emphasis is given to recent theoretical advances related to semileptonic decays, in particular pion pion scattering and Ke4 decays. The systematic approach for including isospin violation and electromagnetic corrections in semileptonic decays is discussed for Kl3 decays.
Correlated PQCD Analysis of the Semileptonic Decays $\overline{B}^0 \to D^{(*)+}\ell^-\barν_\ell$ and the Nonleptonic Decays $ \overline{B}^0 \to D^{(*)+}π^-$
We discuss the validity of factorization for exclusive two-body B to charmonium transitions. In particular, we consider the role of non factorizable corrections in selected two-body modes.
The two-body nonleptonic weak decays of Λ_b \to Λ_c P(V) (P and V represent pseudoscalar and vector mesons respectively) are analyzed in two models, one is the Bethe-Salpeter (B-S) model and the other is the hadronic wave function model. The calculations are carried out in the factorization approach. The obtained results are compared with other model calculations.
We discuss various tests of the factorization hypothesis making use of the close relationship between semi-leptonic and factorized nonleptonic decay amplitudes. It is pointed out that factorization leads to truely model-independent predictions for the ratio of nonleptonic to semi-leptonic decay rates, if in the nonleptonic decay a spin one meson of arbitrary mass or a pion take the place of the lepton pair. Where the decay constants of those mesons are known, these predictions represent ideal tests of the factorization hypothesis. In other cases they may be used to extract the decay constants.…
The nonleptonic two body $B_{u,d,s,c}$ decays involving a light tensor meson in final states are studied in the perturbative QCD approach based on $k_T$ factorization. The decay modes with a tensor meson emitted, are prohibited in naive factorization, since the emission diagram with a tensor meson produced from vacuum is vanished. While contributions from the so-called hard scattering emission diagrams and annihilation type diagrams are important and calculable in the perturbative QCD approach. The branching rations of most decays are in the range of $10^{-4}$ to $10^{-8}$, which are bigger by…
For the first time, a solution to the $a_2/a_1$ sign problem in heavy meson decay based on PQCD factorization theorems. The point is to include QCD evolution effort characteristic scales involved in decay processes.
