Study Of B_c~+�'B_sπ~+ Decay With Perturbative QCD Approach

In recent years, the study of B physics has received much concern in the particle physics. As a particular B meson, B c meson consists of two heavy valence quarks (b quark and c quark). It has various decay channels, which can not only provide us a lot of information for carefully testing the standard model (SM) and determining the model parameters, but also build a platform for researching and developing the new physics beyond SM. With the running of the LHC, we believe that the study of B c meson will push forward the development of the B physics .Some theoretical modes have been introduced into the study of B c meson decays, such as QCD factorization, perturbative QCD approach, QCD sum rules, and soft-collinear effective theory. Each of them has achieved some excellent results. In this thesis, we make a detailed study on the B_c~+�'B_sπ~+ decay with the perturbative QCD approach based on k T factorization. Firstly, we introduce the basic theory for the study of B meson decays—the low energy effective theory, some methods for the hadronic matrix elements, and the perturbative QCD approach. In the research section, we calculate the form factor B_c�'B_swith the perturbative QCD approach. It is found that the form factor is dominated by hard gluon exchange. So the perturbative QCD approach is applicable to this process. At last, we analyse the form factor and branching ratio of B_c~+�'B_sπ~+decay with three kinds of B_s wave functions, and discuss the influences of input parameters on them. The result shows that with reasonable parameters, the form factor of B_c~+�'B_sπ~+is very large, about 10?2 , which is measurable at the running LHC.