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.

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).

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°.

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.

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.

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.