Η ^{η ∞ η}

Since Fermilab found b quark in the year1977, B physics has always been a hot topic of particle physics.The main objective of the B physics is discovering the CP violation of B meson system, measuring the flavor parameters of the standard model (SM),and searching for the signal or evidence of the new physics beyond the SM.From1999to2010, both BaBar and Belle B factory experiments have made great achievements, such as the observation of the CP violation of B meson system, measurements of the branching ratios for hundreds of decay modes. With the running of LHCb in CERN, many B/Bs decays with a branching ratio at the level of10-6have been measured precisely. It offers a solid experimental base for theoretical researches. We therefore believe that this is the best time for the research in the field of heavy flavor physics. Based on the previous studies at the leading order (LO) level, we here will study some Bs→PP decays with the inclusion of the next-to-leading (NLO) contributions by employing the perturbative QCD (pQCD) factorization approach. In this paper, we first recalculate the seven Bs0→PP decays at LO level and then take the NLO contributions into account.In this thesis, we firstly give a short review about the outlines of the SM and the framework of the B meson physics:such as the CKM quark mixing matrix, low energy effective Hamiltonian, the evaluation of the hadronic matrix elements and the pQCD factorization approach. We will calculate the relevant Feynman diagrams of the seven considered decays in LO level and obtain the decay amplitudes. The next step is taking the NLO contributions from different sources into account. From the analytical and numerical results, we found the following points:· For Bs0→π0η、Bs0→π0η′、Bs0→π+π-、Bs0→π0π0decays,the NLO effects are generally small;For Bs0→η(′)η(′)decays,however,the NLO effect is large.· For Bs0→π0η and Bs0→π0η′decays, the NLO corrections have a large effect on their CP-violating asymmetries. · The value of the CP parameter Hf is basically unaffected by NLO correction obviously, its value is close to unit.In the last chapter, a short summary of this thesis and some remarks on future development of B physics are given.