A Study Of New Physics Effects In Bu,dâ†'ππ,Ï€K,KK Decays

The Standard Model is basic theory, developed in the1960s,which describes weak, elec-tric and strong interaction. For decades, the Standard Model has achieved great success, but some problems still exist. It is believed that the standard model is an effective theory at the Fermi scale,there should exist more basic physics at the higher scale. The Two Higgs Doublet Model(2HDM) is a one of the possible theory, it is the simplest extension of the Standard Model. At the same times, the hadronic decay of B meson involves three quark-antiquark bound states, therefore it is regarded that the starting point should be six-quark operator effective Hamiltonian instead of four-quark operator effective Hamiltonian.Starting from the six-quark operator effective Hamiltonian, we systematically study the ten Bâ†'> ππ, Ï€K, KK decay modes under the framework of the standard model and2HD-M, and evalute the branching ratios and direct CP-violation analytically and numerically, Through comparing and analyzing the data,we found the following points:· the new physics mainly modifies the Wilson coefficient function C8g。· The new physics corrections always increase the numerical results of branching ratio in the standard model, and gradually close to the experimental data.· Bâ†'ππ decays mediated by tree and penguin diagrams. For color-allowed tree dom-inated decay modes B0â†'Ï€+Ï€-, B+â†'Ï€+Ï€0, the corrections from new physics can be ignored, while for color-suppressed tree dominated decay mode B0â†'Ï€0Ï€0, new physics effects can not be ignored, but the puzzles do exist.· for Bâ†'KK decay modes. The decay B+â†'K+K0, B0â†'K0K0are bâ†'d penguin dominated modes, the new physics corrections can not be ignored, up to50%; decay Bâ†'K+K-is pure W-exchange mode, the branching ratio is small and the correction of new physics is not small, up to20%because of the contribution from QCD annihilation diagram. · for Bâ†'Ï€ K decays. There are two kind of modes, one is the pure penguin process, e.g B+â†'Ï€+K0, the new physics correction can not be ignored, up to50%, the other is the processes via tree and penguin, e.g. B+â†'Ï€0K+, B0â†'Ï€-K+, B0â†'Ï€0K0, the tree contribution is suppressed and that of bâ†'s penguin is enhanced by CKM factor, the modifications of new physics are large,up to50%.· the corrections of new physics have a strong dependence on MH+, decoupling effect is obvious, i.e, With the increase of MH+, the decreases of correcrtions.· the effects on direct CP violation is small.