B→K Transition Form Factor with Tensor Current within the kT Factorization Approach

We apply the kT factorization approach to deal with the B→K transition form factor with tensor current in the large recoil regions. Main uncertainties for the estimation are discussed and we obtain FT^B→K （0） = 0.25±0.01±0.02, where the first error is caused by the uncertainties from the pionic wavefunctions and the second is from that of the B-meson wavefunctions. This result is consistent with the light-cone sum rule results obtained in the literature.     

B_s → f_0 (980) Transition Form Factors Within the k_T Factorization Approach

In the paper, we apply the kT factorization approach to deal with the Bs → f0 (980) transition form factors in the large recoil regions, i.e. the small q 2 regions. For the purpose, we adopt the B-meson wave-functions ΨB , ΨB and δ that include the three-Fock states contributions to do our discussion. Although the scalar meson f0 (980) is widely perceived as the 4-quark bound state (scenario 2), but the distribution amplitudes of 4-quark states are still unknown to us, so we adopt 2-quark model (scenario 1) for scalar meson f0 (980) in our discussion. By varying the B-meson wave-function parameters within their reasonable regions, we obtain F0(0) = F+(0) = 0.20 ± 0.02, FT(0) = 0.24 ± 0.02. Our present results for these form factors are consistent with the light-cone sum rule results obtained in the literature.     

Bc（B）→DIv^- Form Factors in Light-Cone Sum Rules and the D-Meson Distribution Amplitude

We calculate the weak form factors of the decays Be（B） → Dlv^- by using the chiral current correlator within the framework of the QCD light-cone sum rules （LCSRs）. The expressions of the form factors only depend on the leading twist distribution amplitude （DA） of the D meson. Three models of the D-meson distribution amplitude are employed. Our prediction, by using the D-meson distribution amplitude with the exponential suppression at the end points, favours the three-points sum rule （3PSR） approach with the Coulomb corrections included, and is compatible with other approaches.     

Analysis of B → a_1(1260)(b_1(1235))K decays in the perturbative QCD approach

Within the framework of the perturbative quantum chromodynamics(PQCD) approach, we study the charmless two-body decays B → a_1(1260)K*, b_1(1235)K*. Using the decay constants and the light-cone distribution amplitudes for these mesons derived from the QCD sum rule method, we find the following results.(a) Our predictions for the branching ratios are consistent with the QCD factorization(QCDF) results within errors, but much larger than the naive factorization approach calculation values.(b) We predict that the anomalous polarizations occurring in the decays B→φK*, ρK*also happen in B→a_1 K*decays, while they do not happen in B→b_1 K*decays. Here the contributions from the annihilation diagrams play an important role in explaining the larger transverse polarizations in the B→a_1 K*decays, while they are not sensitive to the polarizations for the B→b_1 K*decays.(c) Our predictions for the direct C P-asymmetries agree well with the QCDF results within errors. The decaysˉB~0→b_1_+K*-, B-→b_1~0K*-have larger direct C P-asymmetries, which could be measured by the present LHCb experiment and the forthcoming Super-B experiment.     

Analysis of B → a1（1260）（b1（1235））K decays in the perturbative QCD approach

Within the framework of the perturbative quantum chromodynamics（PQCD） approach, we study the charmless two-body decays B → a₁（1260）K*, b₁（1235）K*. Using the decay constants and the light-cone distribution amplitudes for these mesons derived from the QCD sum rule method, we find the following results.（a） Our predictions for the branching ratios are consistent with the QCD factorization（QCDF） results within errors, but much larger than the naive factorization approach calculation values.（b） We predict that the anomalous polarizations occurring in the decays B→φK*, ρK*also happen in B→a₁ K*decays, while they do not happen in B→b₁ K*decays. Here the contributions from the annihilation diagrams play an important role in explaining the larger transverse polarizations in the B→a₁ K*decays, while they are not sensitive to the polarizations for the B→b₁ K*decays.（c） Our predictions for the direct C P-asymmetries agree well with the QCDF results within errors. The decaysˉB⁰→b₁₊K*-, B-→b₁⁰K*-have larger direct C P-asymmetries, which could be measured by the present LHCb experiment and the forthcoming Super-B experiment.     

Next-to-leading-order calculation in kT factorization

We explain the framework for calculating next-to-leading-order （NLO） corrections to exclusive processes in the kT factorization theorem, taking πγ^＊→γ as an example. Patrons off-shell by kT^2 are considered in both the quark diagrams from full QCD and the effective diagrams for the pion wave function. The gauge dependences in the above two sets of diagrams cancel, when deriving the kw-dependent hard kernel as their difference. The light-cone singularities in the kT-dependent pion wave function are regularized by rotating the Wilson lines away from the light cone. Both the large double logarithms In^2 kT and In^2x, x being a parton momentum fraction, arise from the loop correction to the virtual photon vertex, the former being absorbed into the pion wave function, and the latter into a jet function.     

New Physics Effects on Rare Decays Bu^＋ → π^＋e^＋e^-, ρ^＋e^＋e^- in a Top Quark Two-Higgs-Doublet Model

Using the form factors from light-cone sum rules, we study the branching ratios and forward-backward asymmetries （FBAs） of the exclusive decays Bu^＋→π^＋e^＋e^- and Bu^＋ →ρ^＋e^＋e^- （e= e,μ） in the standard model （SM） and the top quark two-Higgs-doublet model （T2HDM）. From the numerical results, we find that the new physics contributions cannot provide very large enhancement to the branching ratios and the theoretical predictions are in good agreement with the SM ones. The T2HDM effects on FBAs of these decays are small. Precision measurements of the dilepton invariant mass distributions, especially in the lower dilepton mass region, and the FBAs in the decays Bu^＋ → π^＋ （ρ^＋ ）e^＋ e^- will greatly help in discriminating among the SM and the new physics models.     

B→ηK and B→φKs Decays in the Two Higgs Doublet Model Ⅲ

Using the QCD factorization approach, we investigate the large branching ratios of B→ηK^＊ decays and the SCKs anomaly of B→φKs decay in the two Higgs doublet model Ⅲ. With the contributions of flavour-changing neutral current mediated by the neutral Higgs bosons H^0, h^0 and A^0 at the tree level, we provide a coherent resolution to these anomalies within the constrained parameter spaces, which are 120 〈｜λbs λss｜ 〈136. This will be really interesting in searching for the signs of new physics.     

Finite-Width Correction to Form Factors of γγ^＊→ π^0 Transition

Instead of the usual zero-width approximation for one resonance, we use the finite-width approximation for the two low resonances, i.e. the ρ- ω mesons, to investigate the light-cone local QCD sum rules for the form factor of the transition γγ^＊→ π^0 ,According to the method of the analytic continuation by duality, the weight function, the polynomial of a low order N, is added to the dispersion integral to annihilate the integrand in the region where both resonance saturation and the QCD asymptotic expression are least reliable. The resultant form factor in the cases for the zero- and finite-widths are almost the same, both agree well with the experimental measurements. A comparison with the result from the Laplacian transformed light-cone sum rules and a brief discussion are given.     

Non-factorizable contributions in D0→π+π- decay

We have analyzed the D^0→π^+π^- decay with α_s corrections in quantum chromodynamic (QCD) factorization and with the soft-gluon corrections in the light cone QCD sum rules. The soft-gluon effects are firstly calculated in the decay channel. The results show that once the factorization contributions, the α_s corrections, and the soft-gluon effects are all considered, we can satisfactorily explain the experimental data in the decay channel.     

Radiative Decays of （0^＋, 1^＋） Strange-Bottom Mesons

In this article, we assume that the （0^＋,1^＋） strange-bottom mesons are the conventional bs mesons, and calculate the electromagnetic coupling constants d, g1, g2, and g3 using the light-cone QGD sum rules. Then we study the radiative decays Bs0→Bs^＊γ, Bs1→Bsγ, Bs1→Bs^＊γ, and Bs1→Bs0γ, and observe that the widths are rather narrow. We can search for the （0^＋, 1^＋） strange-bottom mesons in the invariant Bsπ^0 and Bs^＊π^0 mass distributions in the strong decays or in the invariant Bs^＊γ, and Bsγ mass distributions in the radiative decays.     

Role of Electromagnetic Dipole Operator in the Electroweak Penguin Dominated Vector Meson Decays of B Meson

The pure annihilation type decays Dd^0→Фγand Bs→ργ receive only colour suppressed penguin contributions with a very small branching ratio in the standard model. When we include the previously neglected electromagnetic dipole operator, the branching ratios can be enhanced to R（^-Bd^0→Фγ）≈ 1×10^-11 and R（^-Bs→ργ）～（6 - 16） ×10^-10, which are one order magnitude larger than previous study using the QCD factorization approach. The new effect can also give a large contribution, of order 10^-9, to transverse polarization of B→Фρ and B →ωФ, which is comparable to the longitudinal part. These effects can be detected in the LHCb experiment and the super-B factories.     

Study of W-Exchange Mode D0 → ФK0

We calculate the branching ratio of rare decay D^0→ФK using the perturbative QCD factorization approach based on kT factorization. Our result shows this branching ratio is （8.7 ± 1.4） x 10^-3, which is consistent with experimental data. We hope that the CLEO-C and BES-Ⅲ can measure it more accurately, which will help us to understand QCD dynamics and D meson weak decays.     

B → ρ（ω, φ）η（＇） Decays and NLO Contributions in pQCD Approach

By employing the perturbative QCD （pQCD） factorization approach, we calculate some important next- to-leading-order （NLO） contributions to the two-body charmless hadronic decays B^＋ →ρ^＋η（＇） and B^0 → ρ^0（ω, φ）η（＇）, induced by the vertex QCD corrections, the quark-loops as well as the chromo-magnetic penguins. From the numerical results and phenomenological analysis we find that （a） for B^± → ρ^±η（＇） （B^0 → ρ^0（ω, φ）η（＇）decays, the partial NLO contributions to branching ratios are small （large） in magnitude; and （b） the pQCD predictions for ACP^dir（B^± → ρ^±η（＇）） are consistent with the data, while the predicted .ACP（B^0 → ρ^0（ω）η（＇）） are generally large in magnitude and could be tested by the forthcoming LHCb experiments.     

Improved Light-Cone QCD Sum Rule Analysis of Rare Decays Λ_b → Λ_γ and Λ_b → Λl~+ l~-

We present a systematic light-cone QCD sum rule study of the exclusive rare radiative decay Λ b →Λγ and rare semileptonic decay Λ b →Λl + l within the framework of the standard model. Although some light-cone sum rule (LCSR) studies on these rare processes can be found in different literatures, it is necessary to reanalyze them systematically for the reason that either the baryonic distribution amplitudes are improved or different interpolating currents for the Λ b baryon may lead to quite different results. In addition, the rare process Λ b →Λγ has not yet been analyzed by LCSR with the Ioffe-type current. Taking all these reasons into account, we perform LCSR calculations of both the processes with two types of interpolating currents. Our calculations show that the choice of the interpolating current for the Λ b baryon can affect the predictions significantly, especially for the rare radiative decay process.     

Analysis of the decay B^0→Xc1π^0 with light-cone QCD sum rules

In this article, we calculate the contribution from the nonfactorizable soft hadronic matrix element to the decay B^0→Xc1π^0 with the light-cone quantum chromo-dynamic （QCD） sum rules. The numerical results show that its contribution is rather large and should not be neglected. The total amplitudes lead to a branching fraction which is in agreement with the experimental data marginally.     

ρ meson decays of heavy hybrid mesons

We calculate the ρ meson couplings between the heavy hybrid doublets H~h/S~h/M~h/T~h and the ordinary qQˉ doublets in the framework of the light-cone QCD sum rule. The sum rules obtained rely mildly on the Borel parameters in their working regions. The resulting coupling constants are rather small in most cases.     

Off-Shell Photon Light-Cone Transverse Wavefunction at Leading Twist

The explicit expression of the transverse photon wavefunction φγ⊥（u, p2） at the leading twist with the on-shell and the off-shell momenta are calculated in the effective low-energy theory derived from the instanton vacuum of QCD, where both the space-like region as well as the time-like one of the momenta for the virtual photons are investigated. In addition, the problem about the consistency between the two different definitions of the transverse photon wavefunction with chiral-odd Dirac structure, σμν, has been considered, and proven to be true at the leading order by means of the sum rule method. A brief discussion of the dependence of the transverse light-cone photon wavefunction φγ⊥（u, p2） and its coupling, Fγ^⊥（u, P2） to the corresponding quark-antiquark current with respect to p^2, and that about the end-point behaviour of the transverse photon wavefunction is given.     

B→K0^＊（1430）η（＇） decays in the pQCD approach

Based on the assumption of two-quark structure of the scalar meson K0^＊（1430）, we calculate the CP-averaged branching ratios for B→K0^＊（1430）η（＇） decays in the framework of the perturbative QCD （pQCD） approach here. We perform the evaluations in two scenarios for the scalar meson spectrum. We find that： （a） the pQCD predictions for Br（B→K0^＊（1430）η（＇）） which are about 10^-5 10^-6, basically agree with the data within large theoretical uncertainty; （b） the agreement between the pQCD predictions and the data in Scenario Ⅰ is better than that in Scenario Ⅱ, which can be tested by the forthcoming LHC experiments; （c） the annihilation contributions play an important role for these considered decays.     

B→f0（980）（π,η^（＇）） decays in the PQCD approach

Based on the assumption of a two-quark structure of the scalar meson f0（980） ,we calculate the branching ratios and CP-violating asymmetries for the four B → f0（980） π and B → f0（980） η^（＇） decays by employing the perturbative QCD（pQCD） factorization approach. The leading order pQCD predictions for branching ratios are,Br（B^-→ f0（980） π^-） ～ 2.5×10^-6,Br（Bˉ^0 → f0（980） π^0） ～ 2.6×10^-7,Br（Bˉ^0 → f0（980） η） ～ 2.5×10^-7 and Br（Bˉ^0 → f0（980） η ） ～ 6.7×10^-7,which are consistent with both the QCD factorization predictions and the experimental upper limits.