Study Of B_c→DK Decay With Perturbative QCD Approach

Since 1980's,the B meson physics has achieved great success in both theoretical and experimental aspects.Along with the prosperous experimental evolvements in two B meson factories,B meson physics has become one of the most important and the most popular research field in the particle physics.The rare B meson decays provide a good opportunity for testing the Standard Model(SM),probing CP violation and searching for possible new physics beyond the SM.In CERN Large Hadron Collider beauty experiments(LHC-b),it is estimated that one could expect around 5×10¹⁰ B_c events per year.So the studies of B_c meson rare decays are necessary in a few years.Starting with the basic low energy effective theory,the author presents a brief review for the operator product expansion and the four-quark operator.In evaluation the hadronic matrix element,two different factorization approaches beyond the native factorization approach and general factorization approach have been proposed.They are QCD factorization approach and perturbative QCD(PQCD) factorization approach. Comparing the different factorization approaches,a detailed introduction for the basic idea and the key points of the PQCD factorization approach is given also.The approach discusses the problems such an introduction of the transverse momentum k_T,the Sudakov form factor,smearing the end-point divergence,etc.In this thesis,we calculated the branching ratios and CP-violation asymmetries of B_c→DK decay in this approach.The main theoretical predictions are as follows:(1)branching ratio is 6.6×10^-5;(2)direct CP violation is 7%whenγ=60°. Studying the non-leptonic decay of B meson is an important task in particle physics.Any small breakthrough in theory may take new blood to this field.The construction and application in studies of PQCD factorization approach is indeed a great progress in B physics,We expect that the B factory experiments and the upcoming LHC-b experiments can further test or even distinguish different approaches of factorization. We expect that experiments can intending test this theory in future.