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.

Study Pure Annihilation Decays Bs^0（B^-0 s）→D^±π^-＋ in PQCD Approach

The rare decays Bs^0（B^-0 s）→D^±π^-＋ can occur only via annihilation-type diagrams in the standard model. In this paper, we calculate branching ratios of these decays in perturbative QCD approach ignoring soft final state interaction. From our calculation, we find that their branching ratios are at O（10^-6） with large CP asymmetry, which may be measured in LHC-b experiment in the future.

Branching ratio and CP asymmetry of Bs→K0＊ （1430）η（＇） decays in the PQCD approach

In the two-quark model supposition for K0＊（1430）, which can be viewed as either the first excited state （ScenarioⅠ） or the lowest lying state （Scenario Ⅱ）, the branching ratios and the direct CP-violating asymmetries for decays s0 → K0＊0（1430）η （’） are studied by employing the perturbative QCD factorization approach. We find the following results： （a） The CP averaged branching ratios ofs0 → K0＊0 （1430）η ands0→ K0＊0（1430）η’ are small and both in the order of 10-7 . If one views K0＊ （1430） as the lowest lying state, B（s0→K0＊0（1430）η） ≈ 3.9×10-7 and B（s0→K0＊0（1430）η’） ≈ 7.8×10-7.（b） While the direct CP-violating asymmetries of these two decays are not small： if we still take the parameters of K0＊ （1430） in scenario , ACPdir（s0→K0＊0（1430）η） ≈ 56.2% and ACPdir（s0→ K0＊0（1430）η’） ≈ 42.4%. （c） The annihilation contributions will play an important role in accounting for future data, because both the branching ratios and the direct CP asymmetries of these two decays are sensitive to the annihilation type contributions.

B→f_0(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.

B→πη('),η(')η(') decays and NLO contributions in the pQCD approach

By employing the perturbative QCD （pQCD） factorization approach, we calculate the full leading and the partial next-to-leading order （NLO） contributions to the seven B →πη（′） and η（′）η（′） decays. For B^＋→ π＋η（′） decays, the pQCD predictions for their decay rates agree very well with the data after the inclusion of the small NLO contributions. For neutral decays, the pQCD predictions are also consistent with the experimental upper limits and can be tested by the LHC experiments. The measured value of dir .Acp^dir（π＋η）= 19±7% can also be accommodated by the pQCD approach.

Insights into the nature of X(3872)through B meson decays

We study the Bc,u,d→X(3872)P decays in the perturbative QCD(PQCD)approach,involving the puzzling resonance X(3872),where P represents a light pseudoscalar meson(K orπ).Assuming X(3872)to be a 1++charmonium state,we obtain the following results.(a)The branching ratios of the Bc+→X(3872)π+and Bc+→X(3872)K+decays are consistent with the results predicted by the covariant light-front approach within errors;however,they are larger than those given by the generalized factorization approach.(b)The branching ratio of the B+→X(3872)K+decay is predicted as(3.8-1.0+1.1)×10-4,which is smaller than the previous PQCD calculation result but still slightly larger than the upper limits set by Belle and BaBar.Hence,we suggest that the B0,+→X(3872)K0,+decays should be precisely measured by the LHCb and Belle II experiments to help probe the inner structure of X(3872).(c)Compared with the Bu,d→X(3872)K decays,the Bu,d→X(3872)πdecays have significantly smaller branching ratios,which drop to values as low as 10-6.(d)The direct CP violations of these considered decays are small(10-3~10-2)because the penguin contributions are loop suppressed compared to the tree contributions.The mixing-induced CP violation of the B→X(3872)K0S decay is highly consistent with the current world average value sin 2β=(69.9±1.7)%.Experimentally testing the results for the branching ratios and CP violations,including the implicit SU(3)and isospin symmetries of these decays,helps probe the nature of X(3872).

B→D_s^((*))η^(('))Decays in Perturbative QCD

In this paper,we calculate the branching ratios for B^+→D_s^+η,B^+→D_s^+η′,B^+→D_s^(*+)η and B^+→D_s^(*+)η′decays by employing the perturbative QCD (pQCD) factorization approach.Under the two kinds of η-η′ mixingschemes,the quark-flavor mixing scheme and the singlet-octet mixing scheme,we find that the calculated branchingratios agree well with the currently available experimental upper limits.We also consider the so called 'f_D_s puzzle',byusing two groups of parameters about the D_s^((*)) meson decay constants,that are f_D_s = 241 MeV,f_D_s~* = 272 MeV andf_D_s = 274 MeV,f_D_s~* = 312 MeV,to calculate the branching ratios for the considered decays.We find that the resultschange 30% by using these two different kinds of paramters.

The semileptonic decays of B/B_s meson in the perturbative QCD approach:a short review

In this short review,we present the current status about the theoretical and experimental studies for some important semileptonic decays of B=Bsmesons.We firstly gave a brief introduction for the experimental measurements for B=Bs!Peltl;l ml;m mT decays,the BaBar’s ReDT and ReD T anomaly,the P05deviation for B0!K 0ltl decay.We then made a careful discussion about the evaluations for the relevant form factors in the light-cone QCD sum rule,the heavy quark effective theory,and the perturbative QCD factorization approach.By using the form factors calculated in the perturbative(pQCD)approach,we then calculate and show the pQCD predictions for the decay rates of many semileptonic decays of B=Bsmesons.We also made careful phenomenological analysis for these pQCD predictions and found,in general,the following points:(a)For all the considered B=Bssemileptonic decays,the next-to-leading order pQCD predictions for their decay rates agree well with the data and those from other different theoretical methods;(b)For ReDT and ReD T,the pQCD predictions agree very well with the data,the BaBar’s anomaly of ReDe TT are therefore explained successfully in the standard model by employing the pQCD approach;and(c)We defined several new ratios Rl;s Dand Rl;s Ds,they may be more sensitive to the QCD dynamics which controls the B=Bs!eDe T;De T sT transitions than the old ratios,we therefore strongly suggest LHCb and the forthcoming Super-B experiments to measure these new ratios.

The two-body hadronic decays of B_c meson in the perturbative QCD approach:a short review

Along with the running of Large Hadron Collider(LHC)located at CERN in November 2009,a large number of data samples of Bc meson have been collected and some hadronic Bc decay modes have been measured by the LHC experiments.In view of the special and important roles of Bc meson decays playing in the heavy flavor sector,we here give a short review on the status of two body hadronic decays Bc!M1M2at both experimental and theoretical aspects.For the theoretical progresses,specifically,we will show lots of theoretical studies on two body hadronic Bcdecays involving pseudoscalar,vector,scalar,axial-vector,even tensor meson(s)in the final states by employing the perturbative QCD(pQCD)factorization approach.We will present a general analysis about the twobody hadronic decays of the heavy Bc meson and also provide some expectations for the future developments.

微扰QCD方法下的B→D_s^(*)ρ(ω)衰变(英文)

在微扰QCD因子化方法的框架下计算了B+→Ds(*)ρ0,B+→Ds(*)ω0和B+→Ds(*)+ρ-衰变道的分支比.通过计算发现衰变道B+→Ds(*)+ρ0,B+→D(s*)+ω0和B0→Ds(*)+ρ-的分支比在10-5量级,而B0D(s*)+ρ-衰变道的分支比最大,约为1.2×10-4.在这些衰变道中,对于末态包含两个矢量介子的衰变,径向激化的贡献是主要的,并且大于80%;而两个横向激化的贡献是被rDs(*)、rρ(ω)的幂次压低的.

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→a1（1260）K＊, bl （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→ФK＊, pK＊ also happen in B→a1K＊ decays, while they do not happen in B→blK＊ decays. Here the contributions from the annihilation diagrams play an important role in explaining the larger transverse polarizations in the B→alK＊ decays, while they are not sensitive to the polarizations for the B→blK＊ decays. （c） Our predictions for the direct CP-asymmetries agree well with the QCDF results within errors. The decays B-0→b＋K＊-, B-→b0/1K＊- have larger direct CP-asymmetries, which could be measured by the present LHCb experiment and the forthcoming Super-B experiment.

P-wave contributions to B(s)→ψKπ decays in perturbative QCD approach

We study the quasi-two-body decays B(s)ψ[K*(892)K*(1410)K*(1680)]ψKπby employing the perturbative QCD(PQCD)factorization approach,where the charmoniaψrepresents J/ψandψ(2S).The corresponding decay channels are studied by constructing the kaon-pion distribution amplitude(DA)ΦKπP,which comprises important final state interactions between the kaon and pion in the resonant region.Relativistic Breit-Wigner formulas are adopted to parameterize the time-like form factor FKπappearing in the kaon-pion DAs.The SU(3)flavor symmetry breaking effect resulting from the mass difference between the kaon and pion is taken into account,which makes significant contributions to the longitudinal polarizations.The observed branching ratios and the polarization fractions of B(s)ψK*(892)ψKπare accommodated by tuning hadronic parameters for the kaon-pion DAs.The PQCD predictions for B(s)ψ[K*(1410)K*(1680)]ψKπmodes from the same set of parameters can be tested by precise data obtained in the future from LHCb and BelleⅡexperiments.

Study of scalar meson a_0(980) from B→a_0(980)π decays

In this paper, we calculate the branching ratios and the direct CP-violating asymmetries for decays B^0 → a0^0（980）π^0, a0^＋ （980）π^-, a0^-（980）π^＋ and B^- → a0^0 （980）π^-, a0^- （980）π^0 by employing the perturbative QCD （pQCD） factorization approach at the leading order. We found that （a） the pQCD predictions for the branching ratios are around （0.4-2.8） × 10^-6, consistent with currently available experimental upper limits; （b） the CP asymmetries of B^0→ a0^0（980）π^0 and B^- → a0^- （980）π^0 decays can be large, about （70-80）% for α= 100°.

Semileptonic decays B_c →(η_c , J/Ψ)lν in the perturbative QCD approach

In this paper we study the semileptonic decays of Bc→（ηc, J/ψ）1-v1. We first evaluate the Bc→（ηc, J/ψ） transition form factors Fo（q2）, F＋（q2）, V（q2） and Ao,l,2（q2） by employing the pQCD factorization approach, and then we calculate the branching ratios for all considered semileptonic decays. Based on the numerical results and the phenomenological analysis, we find that： （a） the pQCD predictions for the values of the Bc→ηc, and Bc→J/ψ transition form factors agree well with those obtained by using other methods; （b） the pQCD predictions for the branching ratios of the considered decays are Br（B---qe-e（-））= （4.41_1.09）＋1＂22 10-3 Br（B----rl-） ---- （1.37_＋：337） x 10-3, Br（B：--J/kOe-e（li-,））=（iO.03＋：3）〉lO-3, and Br（B：--＊J/＇r-]T）----（2.92_0.34）10＋40 -3., and （c） we also define and calculate two ratios of the branching ratios Rn and Rj/v, which will be tested by LHCb and the forthcoming Super-B experiments.

Revisiting the Kπ puzzle in the pQCD factorization approach

In this paper,we calculated the branching ratios and direct CP violation of the four B→Kπ decays with the inclusion of all currently known next-to-leading order（NLO） contributions by employing the perturbative QCD（pQCD） factorization approach.We found that（a） Besides the 10%enhancement from the NLO vertex corrections,the quark-loops and magnetic penguins,the NLO contributions to the form factors can provide an additional^15%enhancement to the branching ratios,and lead to a very good agreement with the data;（b） The NLO pQCD predictions are A_（CP）^（dir）（B^0→K~＋π~0）=（-6.5±3.1）%and A_（CP）^（dir）（B~＋→K~＋π~0）=（2.2±2.0）%,become well consistent with the data due to the inclusion of the NLO contributions.

用微扰QCD方法研究B_(s)→φρ衰变(英文)

用微扰QCD对B_(s)→φρ衰变进行了研究,考虑了因子化和非因子化图的贡献,得出了B_(s)→φρ衰变的分支比以及纵向极化衰变、横向极化衰变之比,所得到的结果与现在的实验数据吻合．