| As a good place for testing the standard model and searching for possible new physics beyond the SM, B meson decays are getting more and more interesting and attracting more and more attentions. Up to now, the B fatories at KEK and SLAC have collected about 1000 million events of B - (B|-) pair production. In the forthcoming LHC-b experiments, together with 1012 Bu,d events, a large number of heavier Bs,Bc meson pairs will be produced.In evaluating the hadronic matrix element, three different factorization approaches beyond the naive factorization approach and general factorization approach have been proposed. They are QCD factorization approach, perturbative QCD (pQCD) factorization approach and the Soft Collinear Effective Theory (SCET).In the first two chapters, the author introduces the basic knowledge about the B meson physics and the pQCD factorization approach. Starting with the effective theory, the author introduces the operator product expansion, four-quark operators, and makes a comparison with the mentioned factorization approaches. In introducing the idea of pQCD approach , the author discusses the problems such as introduction of the transverse momentum kT, the Sudakov form factor, smearing the end-point divergence,etc.In the second two chapters, the author calculates and analyzes the branching ratios and the CP violation of the seven B→η'η' and B→ω(φ)η' decay channels in the pQCD factorization approach in detail. Primary results are as following: (1)The pQCD predictionsfor the form factors of B→η' and B→ωtransitions are:F0B→η'≈0.27,A0B→ω≈0.35,which are agree well with those obtained in other approaches; (2)The CP-averaged branchingratios for the seven considered decays: Br(B0→ηη) = (0.67-0.25+0.32)×10-7, Br(B0→ηη') = (0.18±0.11)×10-7, Br(B0→η'η') = (0.11-0.09+0.12)×10-7, Br( B0→ωη) =(2.7-1.0+1.1)×10-7, Br( B0→ωη') = (0.75-0.33+0.37)×10-7, Br( B0→φη) = (6.3-1.9=0.33)×10-9,Br( B0→φη') = (7.3-2.6+3.5)×10-9; those results are agree with the latest experimental datum;(3)The direct,mixed and total CP-violating asymmetries of B→η'η' and B→ωη'decays are also calculated in pQCD approach, which have not been measured well yet.These results can be tested in future experiments; (4)According to the phenomenological analysis and calculations, the author therefore believes that the gluonic admixture ofη' should be small, and most possibly not as important as expected before.In the last chapter, a short summary of this paper and some remarks on future developments of B physics in forthcoming years is given. |
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