The transition form factors of the semileptonic $B \rightarrow D_2^*(2460)\ell\barν\,\,\,\,(\ell=τ,μ,e)$ decay channel are calculated within the framework of the three-point QCD sum rules. The fit functions of the form factors are then used to estimate the total decay width and branching ratio of this transition. The order of branching ratio shows that this channel can be detected at LHCb.
The BaBar Collaboration has recently reported branching fractions for semileptonic decays of the $B$ meson into final states with charged and neutral $D_{1}(2420)$ and $D_{2}^{\ast}(2460)$, two narrow orbitally excited charmed mesons. We evaluate these branching fractions within the framework of a constituent quark model in two steps, one which involves a semileptonic decay and the other one mediated by a strong process. Our results are in agreement with the experimental data.
Exclusive semileptonic B meson decays to orbitally excited D mesons are investigated in the infinitely heavy quark limit in the framework of the relativistic quark model based on the quasipotential approach. The B\to D^{**}eνIsgur-Wise functions τ_{3/2}(w) and τ_{1/2}(w) are determined. It is found that the relativistic transformation of the meson wave functions (Wigner rotation of the light quark spin) contribute already at the leading order of the heavy quark expansion.
In this work, using the covariant light front approach with conventional vertex functions, we estimate the production rates of $D$-wave charmed/charmed-strange mesons via $B_{(s)}$ semileptonic decays. Due to these calculated considerable production rates, it is possible to experimentally search for $D$-wave charmed/charmed-strange mesons via the semileptonic decays, which may provide extra approach to explore $D$-wave charmed/charmed-strange mesons.
In this paper we compute, within in the context of a relativistic quark model, the Isgur-Wise functions for exclusive semileptonic $\bar B \to X_c$ decays, where $X_c$ is any charmed mesons with total spin $J=0,1,2$ or one of their first excited states. The relevant matrix elements are computed by a direct numerical integration, in coordinate space, of the convolution of the wave function of the $B$ meson at rest and the wave function of the $X_c$ meson, boosted according with its recoil factor. Our results are compared with other predictions found in the existing literature.
Exclusive semileptonic $B$ decays into excited charmed mesons are studied with QCD sum rules in the leading order of heavy quark effective theory. Two universal Isgur-Wise functions τand ζfor semileptonic B decays into four lowest lying excited $D$ mesons ($D_1$, $D_2^*$, $D'_0$, and $D'_1$) are determined. The decay rates and branching ratios for these processes are calculated.
We derive a Bjorken sum rule for semileptonic $Ω_b$ decays to ground and low-lying negative-parity excited charmed baryon states, in the heavy quark limit. We discuss the restriction from this sum rule on form factors and compare it with some models.
By using a constituent quark model we compute the form factors relevant to semileptonic transitions of B mesons into low-lying p-wave charmed mesons. We evaluate the q^2 dependence of these form factors and compare them with other model calculations. The Isgur-Wise functions tau(1/2) and tau(3/2) are also obtained in the heavy quark limit of our results.
We have obtained the differential decay rate and calculated the branching ratios of the exclusive semileptonic decays $B(D) \to Xlν$, where $X$ is a p-wave meson, using the nonrelativistic ISGW quark model. Our results are compared with the predictions of the ISGW2 model. We have computed some branching ratios that were not reported or were reported with 0.00 in this model. For example, we find that $Br(B_c^- \to \bar{B_{s2}^{*0}}l^-\barν) = 4.03 \times 10^{-5}$, $Br(B_c^- \to \bar{B_2^{*0}}l^- \barν) =3.65 \times 10^{-6}$ and $Br(D_s^+ \to f_2l^+ν) = 2.7 \times 10^{-5}$, which seems to be at …
The BaBar Collaboration has recently reported products of branching fractions that include $B$ meson semileptonic decays into final states with charged and neutral $D_{1}(2420)$ and $D_{2}^{\ast}(2460)$, two narrow orbitally excited charmed mesons. We evaluate these branching fractions, together with those concerning $D_{0}^{\ast}(2400)$ and $D_{1}'(2430)$ mesons, within the framework of a constituent quark model. The calculation is performed in two steps, one of which involves a semileptonic decay and the other is mediated by a strong process. Our results are in agreement with the experimenta…
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.
It is shown that the absolute rate of the semileptonic decays of the $Ξ_c$ baryons can be as much as two times higher than the semileptonic decay rate of $Λ_c$ due to the Pauli interference of the strange quark. This interference effect is still larger in the semileptonic decay rate of $Ω_c$. An experimental measurement of the difference of these rates would thus provide an important piece of information on the spectator effects in decays of hadrons containing a heavy quark.
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…
Semileptonic $B$ meson decays into the four lightest excited charmed meson states ($D_0^*$, $D_1^*$, $D_1$, and $D_2^*$) and their counterparts with $s$ quarks are investigated, including the full lepton mass dependence. We derive the standard model predictions for the differential branching fractions, as well as predictions for the ratios of the semi-tauonic and light lepton semileptonic branching fractions. These can be systematically improved using future measurements of the total or differential semileptonic rates to $e$ and $μ$, as well as the two-body hadronic branching fractions with a …
We study the heavy quark effective theory prediction for semileptonic $B$ decays into an orbital excited $F$-wave charmed doublet, the ($2^{+}$, $3^{+}$) states ($D^{*'}_{2}$, $D_{3}$), at the leading order of heavy quark expansion. The corresponding universal form factor is estimated by using the QCD sum rule method. The decay rates we predict are $Γ_{B\to D^{*'}_{2}\ell\overlineν}=1.85\times10^{-19} {GeV}$ and $Γ_{B\to D_{3}\ell\overlineν}=1.78\times10^{-19} {GeV}$. The branching ratios are $\mathcal {B}(B\to D_{2}^{*'}\ell\overlineν)=4.6\times10^{-7}$ and $\mathcal {B}(B\to D_{3}\ell\overli…
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…
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…
Stimulated by recent progress made by the LHCb Collaboration in discoveries of new bottom baryons, e.g., the $Ξ_{b}(6227)^{-}$ and the $Σ_{b}(6097)^{\pm}$, we re-examine the orbitally excited spectrum of the charmed and bottom baryons using Regge approach in the heavy quark-diquark picture. The results indicate that the spin-averaged mass spectrum of the orbitally-excited charmed and bottom baryons can be described by a linear Regge relation, which is derived from the rotating QCD string model. By giving further mass-splitting analysis of spin-dependent interactions, we explain the baryons $Ξ_…
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.
Within the framework of covariant confined quark model, we compute the transition form factors of $D$ and $D_s$ mesons decaying to light scalar mesons $f_0(980)$ and $a_0(980)$. The transition form factors are then utilized to compute the semileptonic branching fractions. We study the channels namely, $D_{(s)}^+ \to f_0(980) \ell^+ ν_\ell$ and $D \to a_0(980) \ell^+ ν_\ell$ for $\ell = e$ and $μ$. For computation of semileptonic branching fractions, we consider the $a_0(980)$ meson to be the conventional quark-antiquark structure and the $f_0(980)$ meson as the admixture of $s\bar{s}$ and ligh…
We have quantitatively reanalyzed the inclusive charmed-baryon decays. New ingredients are the Voloshin preasymptotic effects in semileptonic decays and the Cabibbo-subleading contributions to both semileptonic and nonleptonic decays. It has been found that the Cabbibo-subleading Voloshin contribution essentially improves the theoretical semileptonic branching ratio of $Λ_c^{+}$, in agreement with experiment. The semileptonic branching ratios for $Ξ_c^{+}$ and $Ω_c^{0}$ are found to be large, i.e., of the order of 20%. The lifetimes hierarchy is in a good qualitative and even quantitative agre…
$b \to c$ semileptonic sum rule: orbitally excited hadrons
KEK Theory Center, IPNS, KEK（高能加速器研究机构理论中心）；Graduate Institute for Advanced Studies, SOKENDAI（日本综合研究大学院大学高等研究院）；Institute for Advanced Research (IAR), Nagoya University（名古屋大学先进研究院）；Kobayashi-Maskawa Institute (KMI) for the Origin of Particles and the Universe, Nagoya University（名古屋大学小林-益川粒子与宇宙起源研究所）；Department of Liberal Arts, Saitama Medical University（埼玉医科大学通识教育部）
研究$b\to c τ\overline{ν}$过渡中涉及轨道激发的重子的半轻子求和规则，探讨偏离小速度极限的现象，指出激发强子导致偏差增大，但相关形式因子尚不充分约束。
We analyze charm meson semileptonic decays using the measured ratios $Γ_L/Γ_T$ and $Γ_{+}/Γ_{-}$ from $D\to {\bar K}^{*}$ and the branching ratios for $D \to {\bar K}^{*}$ and $D \to {\bar K}$. First we introduce the light vector mesons in a model which combines the heavy quark effective Lagrangian and the chiral perturbation approach. We propose a method which predicts the behavior of the form factors. Using the available experimental data we determine the values of some model parameters and reproduce the observed branching ratios for $D_{s} \to Φ$, $D_{s} \to (η+ η^{\prime})$ and $D \to π$. …
Exclusive semileptonic B decays into excited charmed mesons ($D_1$, $D^*_2$) are studied up to the order of $1/m_Q$ in the framework of the heavy quark effective field theory (HQEFT), which contains the contributions of both particles and antiparticles. Two wave functions $η^b_0$ and $η^c_0$, which characterize the contributions from the kinematic operator at the order of $1/m_Q$, are calculated by using QCD sum rule approach in HQEFT. Zero recoil values of other two wave functions $κ'_1$ and $κ'_2$ are extracted from the excited charmed-meson masses. Possible effects from the spin-dependent t…
We use QCD sum rules to estimate the leading-order universal form factors describing the semileptonic B decay into orbital excited $D$-wave charmed doublets, including the ($1^{-}$, $2^{-}$) states ($D_{1}^{*}$, $D'_{2}$) and the ($2^{-}$, $3^{-}$) states ($D_{2}$, $D_{3}^{*}$). The decay rates we predict are $Γ_{B\to D^{*}_{1}\ell\overlineν}=Γ_{B\to D'_{2}\ell\overlineν}=2.4\times10^{-18} {GeV}$, $Γ_{B\to D_{2}\ell\overlineν}=6.2\times10^{-17} {GeV}$, and $Γ_{B\to D_{3}^{*}\ell\overlineν}=8.6\times10^{-17} {GeV}$. The branching ratios are $\mathcal {B}(B\to D^{*}_{1}\ell\overlineν)=\mathcal {…
Once chosen the dynamics in one frame, the rest frame in this paper, the Bakamjian and Thomas method allows to define relativistic quark models in any frame. These models have been shown to provide, in the infinite quark mass limit, fully covariant current form factors as matrix elements of the quark current operator. In this paper we use the rest frame dynamics fitted from the meson spectrum by various authors, already shown to provide a reasonable value for $ρ^2$. From the general formulae for the scaling invariant form factors $ξ^{(n)}(w)$, $τ_{1/2}^{(n)}(w)$ and $τ_{3/2}^{(n)}(w)$, we pred…
Form factors parameterizing the semileptonic decay $B_{c}\rightarrow D_{s}^{\ast}l^{+}l^{-}$ ($l=μ,τ$) are calculated using the frame work of Ward Identities. These form factors are then used to calculate the physical observables like branching ratio and helicity fractions of final state $D_{s}^{\ast}$ meson in these decay modes. The analysis is then extended to the the universal extra dimension (UED) model where the dependence of above mentioned physical variables to the compactification radius R, the only unknown parameter in UED model, is studied. It is shown that the helicity fractions of …
Exclusive semileptonic B decays into excited charmed mesons are investigated at order $Λ_{QCD}/m_Q$ in the heavy quark effective theory. Differential decay rates for each helicity state of the four lightest excited $D$ mesons ($D_1$, $D_2^*$, $D_0^*$, and $D_1^*$) are examined. At zero recoil, $Λ_{QCD}/m_Q$ corrections to the matrix elements of the weak currents can be written in terms of the leading Isgur-Wise functions for the corresponding transition and meson mass splittings. A model independent prediction is found for the slope parameter of the decay rate into helicity zero $D_1$ at zero …
We evaluate exclusive semileptonic decays of ground-state spin-1/2 doubly heavy charmed baryons driven by a $c\to s,d$ transition at the quark level. Our results for the form factors are consistent with heavy quark spin symmetry constraints which are valid in the limit of an infinitely massive charm quark and near zero recoil. Only a few exclusive semileptonic decay channels have been theoretically analyzed before. For those cases we find that our results are in a reasonable agreement with previous calculations.
We evaluate exclusive semileptonic decays of ground-state spin-1/2 doubly heavy charmed baryons. The decays are driven by a $c\to s,d$ transition at the quark level. Our form factors are consistent with Heavy Quark Symmetry constraints. The latter are valid in the limit of infinitely heavy quark mass at zero recoil.
Exclusive semileptonic decays of B mesons to orbitally excited D mesons are considered beyond the infinitely heavy quark limit in the framework of the relativistic quark model based on the quasipotential approach. This model agrees with the structure of heavy quark mass corrections predicted by the heavy quark effective theory and allows the determination of corresponding leading and subleading Isgur-Wise functions. It is found that both relativistic and 1/m_Q contributions significantly influence the decay rates. Thus, relativistic transformations of the meson wave functions (Wigner rotation …
We extend the analysis of weak decays of heavy hadrons to the case of doubly charmed baryons, Ξ_{cc}^{++}, Ξ_{cc}^{+} and Ω_{cc}^{+}. Doubly charmed baryons are modeled as a heavy-light system containing a heavy cc-diquark and a light quark. Such a model leads to preasymptotic effects in semileptonic and nonleptonic decays which are essentially proportional to the meson wave function. Very clear predictions for semileptonic branching ratios and lifetimes of doubly charmed baryons are obtained.
Within the framework of phenomenological Lagrangians we construct the effective action of QCD relevant for the study of semileptonic decays of charmed mesons. Hence we evaluate the form factors of D -> P(0^-) l^+ nu_l at leading order in the 1/N_C expansion and, by demanding their QCD-ruled asymptotic behaviour, we constrain the couplings of the Lagrangian. The features of the model-independent parameterization of form factors provided and their relevance for the analysis of experimental data are pointed out.
We perform an analysis of angular distributions in semileptonic decays of charmed baryons $B_1^{(\prime)}\to B_2^{(\prime)}(\to B_3^{(\prime)}B_4^{(\prime)})\ell^+ν_{\ell}$, where the $B_1=(Λ_c^+,Ξ_c^{(0,+)})$ are the SU(3)-antitriplet baryons and $B_1'=Ω_c^-$ is an SU(3) sextet. We will firstly derive analytic expressions for angular distributions using helicity amplitude technique. Based on the lattice QCD results for $Λ_c^+\toΛ$ and $Ξ_c^0\toΞ^-$ form factors and model calculation of the $Ω_c^0\toΩ^-$ transition, we predict branching fractions: $\mathcal{B}(Λ_{c}^{+} \rightarrow p π^{-} e^{…
The Belle Collaboration has recently reported a study of the decays $B \to D_{s1}(2536)^{+}\bar{D}^{(\ast)}$ and has given also estimates of relevant ratios between branching fractions of decays $B \to D^{(\ast)}D_{sJ}^{(\ast)}$ providing important information to check the structure of the $D_{s0}^{\ast}(2317)$, $D_{s1}(2460)$ and $D_{s1}(2536)$ mesons. The disagreement between experimental data and Heavy Quark Symmetry has been used as an indication that $D_{s0}^{\ast}(2317)$ and $D_{s1}(2460)$ mesons could have a more complex structure than the canonical $c\bar{s}$ one. We analyze these rati…
We obtain tree-level estimates of various differential branching ratios of heavy baryon decays with massive sterile neutrinos $ν_{x}$ in the final state. Heavy sterile neutrinos can be searched for in heavy baryon decays with missing mass as a signature as well as in fixed target experiments, where heavy baryon decays contribute to sterile neutrino production, with sterile neutrino decays as a signature. Generally, charmed baryons are found to be less promising than charmed mesons, in contrast to b-hadrons. In the latter case, branching ratios of beauty mesons and baryons into sterile neutrino…
I review the QCD sum rules calculations of the form factors governing the semileptonic decays of charmed and beauty mesons. In particular, I discuss the predicted dependence of the various form factors on $q^2$ and how it can be obtained for the form factors of vector and axial currents. In some cases the $q^2$ dependence, computed by QCD sum rules, is different from the outcome of lattice QCD. A Tau-Charm factory could be an efficient tool to study this aspect of the charmed meson transitions.
Electroweak Transitions of Hyperons and Charmed Baryons: Opportunities and Prospects
Uppsala University（乌普萨拉大学）；National Centre for Nuclear Research（国家核研究中心）；University of Cyprus（塞浦路斯大学）；The Cyprus Institute（塞浦路斯研究所）；Institute of High Energy Physics（高能物理研究所）；Lund University（隆德大学）；École Polytechnique Fédérale de Lausanne（洛桑联邦理工学院）；University of Graz（格拉茨大学）
In the framework of the heavy quark effective theory, the leading order Isgur-Wise functions relevant to semileptonic decays of the orbitally $P$-wave excited $B_{s}$ meson states $B^{**}_{s}$, including the newly found narrow $B_{s1}(5830)$ and $B^{*}_{s2}(5840)$ states, into the ($D_{s1}(2536)$, $D^{*}_{s2}(2573)$) doublet are calculated from QCD sum rules. With these universal form factors, the decay rates and branching ratios are also estimated.
Exclusive semileptonic B decays to orbitally and radially excited charmed mesons are investigated in the first order of the heavy quark expansion. The emerging leading and subleading Isgur-Wise functions are calculated in the framework of the relativistic quark model. It is found that both relativistic and the 1/m_Q corrections play an important role and substantially modify results. An interesting interplay between different corrections is observed.
Determining for the first time the Darwin operator contribution for the non-leptonic charm-quark decays and using new non-perturbative results for the matrix elements of $ΔC=0$ four-quark operators, including eye-contractions, we present a comprehensive study of the lifetimes of charmed mesons and inclusive semileptonic decay rates as well as the ratios, within the framework of the Heavy Quark Expansion (HQE). We find good agreement with experiment for the ratio $τ(D^+)/τ(D^0)$, for the total $D_s^+$-meson decay rate, for the semileptonic rates of all three mesons $D^0$, $D^+$ and $D_s^+$, and…
Motivated by recent results on charmed baryons from CLEO and FOCUS, we reexamine the couplings of the orbitally excited charmed baryons. Due to its proximity to the [Sigma_c pi] threshold, the strong decays of the Lambda_c(2593) are sensitive to finite width effects. This distorts the shape of the invariant mass spectrum in Lambda_{c1}-> Lambda_c pi^+pi^- from a simple Breit-Wigner resonance, which has implications for the experimental extraction of the Lambda_c(2593) mass and couplings. We perform a fit to unpublished CLEO data which gives M(Lambda_c(2593)) - M(Lambda_c) = 305.6 +- 0.3 MeV an…
Exclusive and inclusive, semileptonic and non-leptonic, charmed decays of the B-meson are investigated in the context of a phenomenological quark model. Bound-state effects are taken care of by adopting a single (model-dependent) non-perturbative wave function, describing the motion of the light spectator quark in the B-meson. A nice reproduction of both exclusive and inclusive semileptonic data is obtained. Our predictions for the electron spectrum are presented and compared with those of the Isgur-Scora-Grinstein-Wise quark model. Finally, our approach is applied to the calculation of inclus…
Recent measurements of the branching fraction for D_s -> l nu disagree with the Standard Model expectation, which relies on calculations of $f_{D_s}$ from lattice QCD. This paper uses recent preliminary measurements from CLEO and a new preliminary lattice-QCD result from this conference to update the significance of the discrepancy. The "f_{D_s} puzzle" stands now at 3.5sigma, with sigma predominantly from the statistical uncertainty of the experiments. New physics scenarios that could solve the puzzle would also lead to non-Standard amplitudes mediating the semileptonic decays D -> K l nu. Th…
We discuss production of charmed mesons as well as electrons/muons from semileptonic decays of charm and bottom mesons in proton-proton collisions at the LHC. The cross section for inclusive production of $c \bar c$ and $b \bar b$ pairs is calculated in the framework of the $k_{\perp}$-factorization approach. Here, the KMR and Jung CCFM unintegrated gluon distribution functions are used. Theoretical uncertainties of the model related to the choice of renormalization and factorization scales as well as due to the quark mass are also discussed. The hadronization of charm and bottom quarks is inc…
It has been recently argued that some longstanding problems in semileptonic B decays can be solved provided the branching ratio for the $B\to D^{\prime(\ast)}$ semileptonic decays are large enough. We have studied these decays in a constituent quark model which has been successful in describing semileptonic and non-leptonic B decays into orbitally excited charmed mesons. Our results do not confirm the hypothesis of large branching ratios for the $B\to D^{\prime(\ast)}$ semileptonic decays. In addition, we calculate the non-leptonic $B\to D'π$ decays which can provide an independent test of the…
We derive mass formulas for the $P$-wave orbitally excited $D^*_{0(s)}$, $D^\prime_{1(s)}$, $D_{1(s)}$, and $D^*_{2(s)}$ heavy charmed mesons including all effects from one-loop corrections that contribute at leading order in chiral expansion. In our formalism, the effects to first order in $m_q$, where $m_q$ is the light quark mass, and to first order in $m^{-1}_c$, where $m_c$ is the charm quark mass, and $m_q/m_c$ terms are considered. The experimental and lattice QCD results on the charmed meson spectra are employed to fix the large number of counterterms appearing in the effective chiral …
A relativistic quark model is extended to incorporate chiral and gauge symmetries. We obtain the DD*pi and DD*gamma couplings and find that the ratio Gamma(D*0->D0pi0)/Gamma(D*0->D0gamma) constrains the charm-quark mass close to 1.45 GeV. Large 1/mc corrections appear in the heavy-quark contribution to the DD*gamma coupling. The model is extended further to describe seven excited D meson states. We find that semileptonic B decays into the ground and excited D meson states do not account for the total semileptonic decay width of the B0. The nonresonant contributions to the processes B0->D(*)pi+…
We use QCD sum rules to estimate the universal form factors describing the semileptonic B decays into excited charmed resonances, such as the $1^-$ and $2^-$ states $D_1^{*}$ and $D_2^{*}$ belonging to the $s_\ell^P={3/2}^-$ heavy quark doublet, and the $2^-$ and $3^-$ states $D_2^{*\prime}$ and $D_3$ belonging to the $s_\ell^P={5\2}^-$ doublet.
Relativistic properties of qqbar potentail, mass spectra of orbitally and radially excited B and D mesons as well as semileptonic decays of B mesons to orbitally excited D mesons are discussed in the framework of the relativistic quark model based on the quasipotential approach.
Exclusive semileptonic B decays are discussed. The emphasis is on using semileptonic decays to determine |V_{ub}| and |V_{cb}|. Recent progress in our understanding of B semileptonic decays to excited charmed mesons is also reviewed.
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…
We present an analysis of semileptonic decays of orbitally, $P$-wave excited $B_{s}$ meson states $B^{**}_{s}$, including the newly found narrow $B_{s1}(5830)$ and $B^{*}_{s2}(5840)$ states, into low lying $D_{s}$ mesons ($D_{s}(1968)$, $D^{*}_{s}(2112)$, $D_{sJ}(2317)$, $D_{sJ}(2460)$) within the framework of heavy quark effective theory. The relevant universal form factors are estimated using QCD sum rules at the leading-order of the heavy quark expansion. The decay widths are predicted and the branching ratios are estimated.
We present the results of a calculation of the perturbative QCD corrections for the semileptonic inclusive width of a heavy flavored meson. Within the Heavy Quark Expansion we analytically compute the QCD correction to the coefficient of power suppressed contribution of the chromo-magnetic operator in the limit of vanishing mass of the final state quark. The important phenomenological applications are decays of bottom mesons, and to the less extend, charmed mesons.
We re-investigate the effects of the $1/m_c$ corrections on the spectrum of the lowest orbitally excited $D$-meson states. We argue that one should expect the $1/m_c$ corrections to induce a significant mixing between the two lowest lying $1^+$ states. We discuss the implications of this mixing and compute its effect on the semileptonic decays $B \to D^{**} \ell \barν$ and the strong $D^{**}$ decays.
We study the semileptonic branching fraction of $B$-meson into higher resonance of charmed meson $D^{**}$ by using the Bjorken sum rule and the heavy quark effective theory(HQET). This sum rule and the current experiment of $B$-meson semileptonic decay into $D$ and $D^*$ predict that the branching ratio into $D^{**}lν_l$ is about 1.7\%. This predicted value is larger than the value obtained by the various theoretical hadron models based on the HQET.
