The New Physics Corrections B → PV Decays And The Fourth Generation Of Quarks

As is well known, for both experimental measurements and theoretical studies, the three major objectives of B meson physics are:searching for CP violation in the B meson system; testing the standard model (SM) and measuring the parameters of flavor sector of the SM, and searching for the signals or the evidence of new physics beyond the SM. On experimental side, two B factories, LHCb and other relevant experiments have been collected a lot of data for the pair production and decays of B mesons. The decay processes with a branching ratio at the level of10-6can be measured precisely. The improvement of experimental precision provide new opportunities and challenges to theoretical calculations. In this thesis, we study the two-body charmless hadronic B meson decays in the framework of the SM and the SM with the fourth generation of quarks (i.e SM4). We studied24B→PV (here P and V denote the pseudo-scalar and vector light mesons) decays by employing the perturbative QCD (pQCD) factorization approach.In the review part of this thesis, we firstly give a short introduction of the SM. the PQCD factorization approach and CP violation etc. we focus on the introduction for the pQCD factorization approach. In third chapter, we make a brief review about the SM4model. We calculated the new physics loop contributions to the Wilson coefficients induced by new particles appeared in the SM4model.In chapter four, we calculated the branching ratios and CP violations of the twenty four B→PV PV decay models in both the SM and the SM4model by employing the PQCD factorization approach. By phenomenological analysis, we found the following points:●For those tree-dominated decays, the new physics contributions are very small and can be neglected safely.●For B→π0K*0,B0→π0ρ0,B0→π(ω,φ),and B0→φη’decays, the new physical contributions in the SM4model can provide significant enhancements to the branching ratios, from22%to388%in magnitude. ●For B+→ρ+η(’) and B0→ωη(’) decays, the new physics contributions are very small and can be neglected safely.●For B→(ρ,ω)π,(ρ,ω)η(’) decays, the pQCD predictions for the branching ratios have e weak dependence on the variations of mt’ and φt’, but the pQCD predictions for the direct CP-violations are sensitive to the variations of φt’.●For the CP-violating parameters C, S, ΔC and ΔS, a strong enhancement up to186%can be obtained when the new physics contributions in the SM4are taken into account.In the last chapter, a short summary of this thesis and some remarks on future devel-opment of B physics in forthcoming years are given.