Study of semileptonic decays B_s →D_(s1)(2536)l and B_s →D_(s2)(2573)l in the CQM model

Based on the assumption that Ds1(2536) and Ds2(2573) belong to T doublet (1 ,2 ), we calculate the semileptonic decays of Bs to Ds1(2536) and Ds2(2573) in terms of the Constituent Quark Meson (CQM) model. For Bs → Ds1(2536) l, and Bs → Ds2(2573) l, the order of magnitude of the obtained branching ratios is 10-3. Our numerical results of the semileptonic decays of Bs to Ds1(2536) and Ds2(2573) are large, which implies that two semileptonic decays should be seen in future experiments.     

Pure annihilation type decays B0→Ds- K2+ and Bs→Da2 in perturbative QCD approach

We calculate the branching ratios of pure annihilation type decays B⁰→D_s^- K₂^*+ and B_s→Da₂ using the perturbative QCD approach based on k_T factorization. The branching ratios are predicted to be (60.6_{-16.5-10.4-2.1}^{+17.3+4.3+3.2} )× 10^-6 for B⁰→D_s^- K₂^*+, (1.1_-0.4-0.2-0.1^+0.4+0.1+0.1)×10^-6 for B_s→D⁰a₂⁰ and (2.3_-0.8-0.4-0.1^+0.8+0.2+0.1)×10^-6 for B_s→D^-a₂⁺. They are large enough to be measured in the ongoing experiment. Due to the shortage of contributions from penguin operators, there are no direct CP asymmetries for these decays in the Standard Model. We also derive simple relations among these decay channels to reduce theoretical uncertainties for the experiments to test the accuracy of theory and search of new physics signal.     

Study of ψ(4415) in the QPC model

Some authors consider the ψ(4415) to be the 4S or 5S excited tate of a cc pair. Starting from this assumption, we study he decays of the ψ(4415) to DD, D^*D^*, D_SD_S, D_S^*D_S^*, and get the corresponding branching ratios in terms of the Quark-Pair-Creation (QPC) model. Compared with the experimental data, we find that the results of 4S state agree much better than those of the 5S state. Therefore, it is more reasonable to assume the ψ(4415) to be a 4S state.     

Semileptonic decays Bc→(ηc,J/Ψ)lv in the perturbative QCD approach

In this paper we study the semileptonic decays of B_c^-→(η_c,J/Ψ)l^-v_l. We first evaluate the B_c→(η_c,J/Ψ) transition form factors F₀(q²), F₊(q²), V(q²) and A_0,1,2(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 B_c→η_c and B_c→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_c^-→η_c e^-v_e(μ^-v_μ)=(4.41_-1.09^+1.22)×10^-3, Br(B_c^-→η_cτ^-v_τ) =(1.37_-0.34^+0.37)×10^-3, Br(B_c^-→J/Ψ e^-v_e(μ^-v_μ)) =(10.03_-1.18^+1.33)×10^-3, and Br(B_c^-→J/Ψτ^-v_τ) =(2.92_-0.34^+0.40)×10^-3; and (c) we also define and calculate two ratios of the branching ratios R_ηc and R_J/Ψ, which will be tested by LHCb and the forthcoming Super-B experiments.     

Uncertainty study of DS-(D-)→γlν (l=e,μ) decays determined by wave function

Wave function is important for determining decay constants f_DS^- and f_D^-. Using the 5 types of D meson wave functions in the heavy quark limit, we studied the uncertainties of radiative pure-leptonic decays of D_S^-(D^-) mesons. The branching ratios are (1.025390—1.706812) × 10^-5 and (0.953498—1.576725) × 10^-6 for D_S^- and D^- decays, respectively, which are sensitive to the type of wave function.     

Study of the η’→Ve~+e~- decay with hidden local symmetry model

Within the hidden local symmetry framework, the Dalitz decay η→Ve+e-is studied with the vector meson dominance model. It is found that the partial width Γ(η→ωe+e-)≈40 e V and branching ratio B(η→ωe+e-)≈2×10-4, and Γ(η→ρe+e-)≈10Γ(η→ωe+e-) and B(η→ρe+e-)≈10B(η→ωe+e-). The maximum position of the dilepton distribution is m e+e-≈1.33 Me V. These decays are measurable with the advent of high statistic ηexperiments.     

Pure annihilation type decays B0→Ds- （K2*）+ and Bs →a2 in the perturbative QCD approach

We calculate the branching ratios of pure annihilation type decays B 0 →D_s^- （K₂^*）⁺ and Bs → a₂ using the perturbative QCD approach based on k T factorization. The branching ratios are predicted to be （60.6 +17.3+4.3+3.2 16.5 10.4 2.1 ）× 10^-6 for B⁰ →D_s^- （K₂^*）⁺ , （1.1 +0.4+0.1+0.1-0.4-0.2-0.1 ）×10-6 for Bs → ⁰a₂⁰ and （2.3 +0.8+0.2+0.1-0.8-0.4-0.1 ）×10-6 for Bs→D^-a₂⁺ . They are large enough to be measured in the ongoing experiment. Due to the shortage of contributions from penguin operators, there are no direct CP asymmetries for these decays in the Standard Model. We also derive simple relations among these decay channels to reduce theoretical uncertainties for the experiments, to test the accuracy of theory, and to search for a signal of new physics.     

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 ofs0 → K0*0 (1430)η ands0→ 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 Λb→pK- and pπ- decays in a flavor changing Z' mode

In this paper, we calculate the branching ratios of Λ_b→pK^- and pπ^- decays in the avor changing Z' model. We nd that the branching ratios for these two decay modes are sensitive to the contributions of the Z' boson. For Λ_b→pK^- decay, if the left-handed couplings are equal to the right-handed couplings, the branching ratio of this decay could match up to the currently experimental data for ξ_s=0.01 and -52°<φ_s^L<132°, or ξ_s=0.004 and 0°<φ_s^L<84°; if only the left-handed couplings are considered, it could match up to the experimental data for ξ_s=0.01 and -10°φ_s^L<138°. And for Λ_b→pK^- decay, if the left-handed and right-handed couplings are equal, the branching ratio of Λ_b→pK^- decay may be consistent with the currently experimental data with ξ_d=0.05 and -135°φ_d^L<43°, if only the left-handed couplings are considered, it may be consistent with ξ_d=0.05 and -114°φ_d^L<8°.     

Semileptonic decays B_c■(η_c,J/ψ)l■_l in the “PQCD+Lattice” approach

We study the semileptonic decaysBc-→(ηc,J/ψ)l-■lusing the PQCD factorization approach with the newly defined distribution amplitudes of the B c meson and a new kind of parametrization for extrapolating the form factors which takes into account the recent lattice QCD results.We find the following main results:(a)the PQCD predictions of the branching ratios of theBc→(ηc,J/ψ)l■decays are smaller by about 5%-16%when the lattice results are taken into account in the extrapolation of the relevant form factors;(b)the PQCD predictions of the ratio Rηc,RJ/ψand of the longitudinal polarization PτareRηc=0.34±0.01,RJ/ψ=0.28±0.01,Pτ(ηc)=0.37±0.01and Pτ(J/ψ)=-0.55±0.01;and(c)after including the lattice results,the theoretical predictions slightly change:Rηc=0.31±0.01,RJ/ψ=0.27±0.01,Pτ(ηc)=0.36±0.01andPτ(J/ψ)=-0.53±0.01.The theoretical predictions of RJ/ψagree with the measurements within the errors.The other predictions could be tested by the LHCb experiment in the near future.     

Study of Radiative Decays Ds1(2536) → Ds(1968)+γ andDs1(2536) → Ds*(2112)+γ in CQM Model

There are some uncertain characteristics of the D_s1(2536), which deserves further discussion. Based on the assumption that the meson is constituted by c\bar{s}, and belongs to T doublet (1⁺,2⁺), radiative decays D_s1(2536)→D_s(1968)+γ and D_s1(2536)→ D_s*(2112)+γ are studied in the CQM model. The large branching ratios of them from our calculations not only indicate the process may be detected in the future experiments, but also can give a deep comprehension of the structure of it.     

Analysis of Bs→φμ+μ- decay within supersymmetry

Motivated by the rst measurement on B(B_s→φμ⁺μ^-) by the CDF Collaboration, we study the supersymmetric e ects in semi-leptonic B_s→φμ⁺μ^- decay. In our evaluations, we analyze the dependences of the dimuon invariant mass spectrum and the forward-backward asymmetry on relevant supersymmetric couplings in the MSSM with and without R-parity. The analyses show that the new experimental upper limits of B(B_s→φμ⁺μ^-)from the LHCb Collaboration could further improve the bounds on sneutrino exchange couplings and (δ_LL^u)₂₃ as well as (δ_LL,RR^u)₂₃ mass insertion couplings. In addition, within the allowed ranges of relevant couplings under the constraints from B(B_s→φμ⁺μ^-), B(B→K^(*)μ⁺μ^-) and (B_s→φμ⁺μ^-), the dimuon forward-backward asymmetry and the di erential dimuon forward-backward asymmetry of B_s→φμ⁺μ^-are highly sensitive to the squark exchange contribution and the (δ_LL^u)₂₃ mass insertion contribution. The results obtained in this work will be very useful in searching for supersymmetric signals at the LHC.     

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.     

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 (Scenario Ⅰ) or the lowest lying state (Scenario Ⅱ), the branching ratios and the direct CP-violating asymmetries for decays B_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 of B_s⁰→K₀^*0(1430)η and B_s⁰→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 (B_s⁰→K₀^*0(1430)η)≈3.9×10^-7 and B (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 Ⅱ, A_CP^dir (B_s⁰→K₀^*0(1430)η)≈56.2% and A_CP^dir (B_s⁰→K₀^*0(1430)η')≈2.4%. (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.     

Pure annihilation type decays B0→Ds- K2*+ and Bs→Da2 in perturbative QCD approach

We calculate the branching ratios of pure annihilation type decays B⁰→D_s^- K₂^*+ and B_s→Da₂ using the perturbative QCD approach based on k_T factorization. The branching ratios are predicted to be (60.6_{-16.5-10.4-2.1}^{+17.3+4.3+3.2} )× 10^-6 for B⁰→D_s^- K₂^*+, (1.1_-0.4-0.2-0.1^+0.4+0.1+0.1)×10^-6 for B_s→D⁰a₂⁰ and (2.3_-0.8-0.4-0.1^+0.8+0.2+0.1)×10^-6 for B_s→D^-a₂⁺. They are large enough to be measured in the ongoing experiment. Due to the shortage of contributions from penguin operators, there are no direct CP asymmetries for these decays in the Standard Model. We also derive simple relations among these decay channels to reduce theoretical uncertainties for the experiments to test the accuracy of theory and search of new physics signal.     

The study of B→K()l+l- decays in family non-universal Z' models

In a combined investigation of B→K^(*)l⁺l^- decays, constraints on the related couplings in family non-universal Z' models are derived. We find that within the allowed parameter space, the recently observed forward-backward asymmetry in the B→K^(*)l⁺l^- decay can be explained by flipping the signs of the Wilson coefficients C₉^eff and C₁₀. With the obtained constraints, we also calculate the branching ratio of the B_s→μ⁺μ^- decay. The upper bound of our prediction is nearly an order of magnitude smaller than the upper bound given by the CDF Collaboration recently.     

Study of Ds±→μ±νμ at Belle

We present a preliminary measurement of the B(D_s→μν_μ) with the Belle     

The study of B→K*l+l- decays in family non-universal Z′ models

In a combined investigation of B → K ( * ) l + l - decays, constraints on the related couplings in family non-universal Z′ models are derived. We find that within the allowed parameter space, the recently observed forward-backward asymmetry in the B → K * l + l - decay can be explained by flipping the signs of the Wilson coefficients C eff 9 and C 10 . With the obtained constraints, we also calculate the branching ratio of the B s →μ + μ - decay. The upper bound of our prediction is nearly an order of magnitude smaller than the upper bound given by the CDF Collaboration recently.     

Production of the new gauge boson BH via e－ collision in the littlest Higgs model

The lightest new gauge boson B_H with mass of hundreds GeV is predicted in the littlest Higgs model. B_H should be accessible in the planned ILC and the observation of such particle can strongly support the littlest Higgs model. The realization of γγ and e^－γ collisions would open a wider window to probe B_H. In this paper, we study the new gauge boson B_H production processes e－γ→e－γ