Study Of B Meson Two-body Decay

In recent 50 years,with the rapid development of particle physics,B meson physics has become a hot research field in high energy physics,it is an important place to test the standard model and explore new physics.One of the core problems in B meson physics is the calculation of hadronic matrix elements for B meson decay.The first two chapters of this paper introduce the basic knowledge of meson physics briefly,Two main methods to calculate hadronic matrix elements are introduced in this paper in detail.The third and fourth chapters of this paper are the working part.The relevant results are as follows:Through analyzing theB_s charmed decaysB⁰????₀f₀?980?andB_s????₀ f₀?980?within the framework of the perturbative QCD factorization approach and comparing with the current data,we find that there are two pos???ible regions for thef₀?980?-f₀?500?mixing angle ?:one is centered at 34°–38°and the other falls into 142°–154°.The former can overlap mostly with one of the allowed angle regions extracted from the decayB°????₀ f₀?500?.The branching fractions ofB_s decay modes are less sensitive to the mixing angle compared with those of B decay modes.Especially,for the decayB_s????₀ f₀?980?,its branching fraction changes only slightly between?1.2-1.8?×10^-7when the mixing angle?runs from 0°to180°.All of our results support the picture that thef₀?980?is dominated by the two-quark component in the B decay dynamic mechanism.Furthermore,the s???component is more important than the q???=?u???+d????/2^1/2 component.This point is different fromf₀?500?/?.Last but not least,our picture is not in conflict with the popular four-quark explanation.We study the B meson decaysB?J/?K₁?1270,1400?in the PQCD approach beyond the leading order.With the vertex corrections and the NLO Wilson coefficients included,the branching ratios of the considered decays are predicted as following,when mixing angle?_K1=33⁰,Br?B⁺?J/?K₁?1270?⁺?=1.76_-0.69^+0.65×10^-3,Br?B⁺?J/?K₁?1400?⁺?=6.47_-2.34^2.50×10^-4,andBr?B⁰?J/?K₁?1270?⁺?=1.63_-0.64^+0.60×10^-3which can agree well with the data or the present experiment upper limit within errors.So we support the opinion that?_k1³3⁰ is much more favored than 58⁰.Futhermore,we also give the predictions of the polarization fractions,the direct CP violations,the relative phase angles for the considered decays with the mixing angle?_K1=33⁰and58⁰,respectively.The directly CP violations of the two charged decaysB⁺?J/?K₁?1270?⁺,B⁺?J/?K₁?1400?⁺are very small(10^-410^-5),because the weak phase is very tiny.In order to check the dependence of the results on the nonperturbative input parameters,we also calculate them by using the harmonic-oscillator type wave functions for the J/?meson.These results can be tested at the running LHCb and forthcoming Super-B experiments.In chapter 5,we summarize the whole paper and look forward to the future of b-meson physics experiment and theoretical research.