| B meson physics has been one of the hot topics of the high energy particle physics. It is necessary for us to provide the theoretical predictions for the physical observables about the B meson decays and compare these theoretical results with those measured values, in order to test the standard model (SM) and to find the signal of new physics beyond the SM. The QCD dynamics involved in the B meson decays is complex in nature. In order to calculate the hadronic matrix elements of B meson decays reliably, several factorization approaches have been constructed in recent years:the perturbative QCD (pQCD) factorization approach is one of such approaches. By employing the effective Hamiltonian method and the pQCD factorization approach, one can deal with the hadronic two-body B meson decays B?M2M3 reliably.As is well-know, the main difficulty lies in B meson physics is the calculation of hadron matrix elements. Although the effective Hamiltonian has been improved greatly, the evalua-tions for the B meson transition form factors do have large theoretical uncertainties, due to the existence of the non-perturbative QCD contributions in such processes. During the past decades, many two-body hadronic B ?M2M3 decays have been studied by employing the pQCD factorization approach at the leading order (LO) level or the partial next-to-leading (NLO) order.In this paper, we present our studies on the hadronic B??+?-,?+?0 and ?0?0 decays by using the pQCD approach. We firstly give a brief review about the decays and the CP vio-lation of the B meson system, and present a short introduction about the basics of the pQCD factorization approach; We then calculate the polarization fractions, the branching ratios and the CP-violating asymmetries of the three considered decay modes:B? (?+?-.?+?0,?0?0) in the pQCD approach at the full leading order and with the inclusion of currently known NLO contributions; Based on the numerical results and the phenomenological analysis, we found that ? For branching ratio B0??+?-, there exist a clear difference between the LO pQCD prediction and the measured value from the BaBar and Belle experiments. But the pQCD results become consistent with the data after the inclusion of the NLO contri-butions. For other two decays, the agreement between the theory and the data also improved to some extent by the inclusion of the NLO pieces.? For the longitudinal polarization fractions of B0??+?- and B+ ??+?0 decays, the pQCD predictions are 95?98%, agree well with those measured values. That means that there is no polarization anomaly for these two decays.? For B0??0?0 decay, the longitudinal polarization fraction is around 50%, while the "normal" and "transverse" fraction share the remaining part.? We show the pQCD predictions for the CP vilating asymmetries of the considered three decay modes, but can not compare them with the data because the relevant measurements still have large uncertainties.A short summary of this thesis and some remarks on future development of B physics are given in the last chapter.Studying the non-leptonic decays of B meson is an important work in the particle physics. During the past years, many good researches have been done in this area. The pQCD fac-torization approach itself are also improved rapidly. We expect that the future experiments can provide a great help to test the pQCD approach. |
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