Two-body nonleptonic decays of the heavy mesons in the factorization approach

In the framework of the factorization approach we calculate the branching fractions of 100 two-body nonleptonic decay channels in total,including 44 channels of the charm meson decays and 56 channels of the bottom meson decays.For charm meson decays,we test and confirm the previous observation that taking the limit for the number of colors N→∞significantly improves theoretical predictions.For bottom meson decays,the penguin contributions are included in addition.As an essential input,we employ the weak decay form factors obtained in the framework of the relativistic quark model based on the quasi-potential approach.These form factors have well been tested by calculating observables in the semileptonic D and B meson decays and confronting obtained results with experimental data.In general,the predictions for the nonleptonic decay branching fractions are acceptable.However,for a quantitative calculation it is necessary to account for a more subtle effects of the final-state interaction.

B_(c)→J/ψhelicity form factors and the B_(c)^(+)→J/ψ+(P,V,ℓ^(+)ν_(ℓ))decays

In this paper,we calculate the B_(c)→J/ψhelicity form factors(HFFs)up to twist-4 accuracy by using the light-cone sum rules(LCSR)approach.After extrapolating those HFFs to the physically allowable q^(2)region,we investigate the B_(c)^(+)-meson two-body decays and semi-leptonic decays B_(c)^(+)→J/ψ+(P,V,ℓ^(+)ν_(ℓ)),where P/V stand for light pseudoscalar and vector mesons,respectively.The branching fractions can be derived using the CKM matrix element and the B_(c)lifetime from the Particle Data Group,and we obtain B(B^(+)_(c)→J/ψπ^(+))=(0.136+0.002−0.002)%,B(B^(+)_(c)→J/ψK^(+))=(0.010+0.000−0.000)%,B(B^(+)_(c)→J/ψρ+)=(0.768+0.029−0.033)%,B(B^(+)_(c)→J/ψK^(∗+))=(0.043+0.001−0.001)%,B(B^(+)_(c)→J/ψ_(μ)+ν_(μ))=(2.802+0.526−0.675)%and B(B^(+)_(c)→J/ψτ^(+)ν_(τ))=(0.559+0.131−0.170)%.We then obtain R_(π^(+)/μ+ν_(μ))=0.048+0.009−0.012 and R_(K^(+)/π^(+))=0.075+0.005−0.005,which agree with the LHCb measured value within 1σ-error.We also obtain R_(J/ψ)=0.199+0.060−0.077,which like other theoretical predictions,is consistent with the LHCb measured value within 2σ-error.These imply that the HFFs under the LCSR approach are also applicable to the B+c meson two-body decays and semi-leptonic decays B+c→J/ψ+(P,V,ℓ^(+)ν_(ℓ)),and the HFFs obtained using LCSR in a new way implies that there may be new physics in the B_(c)→J/ψℓ^(+)ν_(ℓ)semi-leptonic decays.

Study of ■ decay parameter in J/ψ→Λ■ decay

The helicity amplitudes for Jψ→ ∧∧ and the relevant background decays are presented for measuring the ∧ decay parameter α ＋（∧ → pπ^＋） in J/ψ→ ∧∧. The Monte Carlo （MC） simulations based on the helicity amplitudes information are carried out. The likelihood fit method to determine the .∧ decay parameter is presented. Based on the MC generated sample, the sensitivity of the measurement for α＋ has been estimated, which shows that the J/ψ→ ∧∧ channel can be used to measure the .∧ decay parameter α＋（∧ → pπ^＋） well.