Perturbative Qcd Factorization Method Under B ¡ú Pp Decay Process Amendments To The Two-higgs Model

The main objective of the elementary particle physics is to find the physical laws at short scale. On the past several decades, the standard model (SM) which describes the elementary particles and their interactions, has gain enormous success. However, there exists some problems which havn't been solved yet, it is believed that the SM is a effective theory at the fermi scale (v≈246GeV), at the higher scale there should exist more basic theory. In resent years, by the promotion of B factories and other B experiments, B physics are attracting more and more attentions, since they provide a good place for testing the SM, checking QCD. studying CP violation and searching new physics.In the framework of the SM and the two-Higgs-doublet model(2HDM), we made a systematic study for the charmless hadronic B meson decays to two pseudoscalar mesons and found some interesting results.In the first two chapters, we gave a brief review for the SM and the charmless hadronic B meson decays, presented the theoretical framework of B physics, which includes the effective Hamiltonian and the operator product expansion, the calculation of the hadronic matrix element, the idea and method of perturbative QCD (pQCD) and making a compar-ison with different factorization methods, discussing the problems such as introduction of the transverse momentum kT, the Sudakov form factor, the resummation of the threshold value, the wave functions of the mesons.In chapter 3, we introduced the general 2HDM's and the currently available experi-mental constraints, mainly focus on modelâ…¢.In chapter 4, based on the pQCD factorization approach with two pseudoscalar mesons, we studied the two-body charmless hadronic decays of B meson, and gave the analytical results. In the pQCD approach, we not only calculate the usual factorizable contributions, but also evaluate the non-factorizable and annihilation type contributions. Besides the current-current operators, the contributions from the magnetic-penguin op-erators are also taken into account. In chapter 5, we give the numerical results of the branching ratios and CP-violating asymmetries for the charmless hadronic decays of B meson to two pseudoscalar mesons, then we considered the contribution of the two-Higgs model (Modelâ…¢) of the new physics. Within the considered paramater space, we found the following:1. For all 21 decay modes, the SM predictions for the branching ratios and CP-violating asymmetries obtained here agree well with those presented in earlier papers.2. In modelâ…¢, there is a little contribution of the new physics to the leading order decay amplitude which calculated with the pQCD approach.3. However, when we consider the contributions of the magnetic-penguin operators, the new physics enhancements can be significant,δB～(20-200)%.4. In modelâ…¢, the new physics enhancements to ratios Br(Bâ†'Kη') are significant,～(45 - 200)%, give a simple new physics signal for the measured large Bâ†'Kη' decay rates.5. The theoretical predictions of Br(Bâ†'PP) in the 2HDM's are generally consistent with experimental measurements and upper limits.At last, we made a short summary of this paper and some remarks on future devel-opments of B physics in forthcoming years.