| The establishment of the Standard Model(SM)provides strong theoretical support for people to study particle physics.The B meson(include Bu,d,Bsand Bcin general)physics has made a great contribution to the precision test of the SM.In recent years,a series of important achievements have been made in the experimental detections and theoretical researches of the two-body hadronic B meson decays.With the ongoing running of the LHCb and Belle-II experiments,more and more events of the three-body hadronic B meson decays have been collected,the branching ratios,the CP violating asymmetries and other physical observables have been measured.However,the corresponding theoretical framework of three-body hadronic B meson decays has not yet been established maturely.Currently,the framework of the quasi-two-body decays of B mesons is widely used to make theoretical explanations and predictions for the three-body hadronic B meson decays.Based on the framework of the perturbative QCD(PQCD)factorization approach,we study the quasi-two-body hadronic B(s)meson decays,and evaluate the possible contributions from the resonant states.In Chapter 2,the author will make a brief introduction to the basic theoretical knowledge of the SM,the CKM mixing matrix and the low-energy effective Hamiltonian involved in B meson physics.The PQCD factorization approach will also be introduced in detail in this chapter.In Chapter 3,the author focuses on the basic kinematics of the three-body hadronic B meson decays,including the introduction of the Dalitz diagram,the explanation and analysis of the concept of the relevant resonant states,and finally expounds the calculation and analysis of the quasi-two-body hadronic B meson decays in the PQCD factorization approach.In Chapter 4,by employing the PQCD factorization approach,,the author makes a systematic study for some quasi-two-body hadronic decays: B(s)?(D,(?))[R ?]KK.The emphasis is to find the proper way to absorb the final resonant state contribution into the two meson distribution amplitude of KK pair.The correlative parameters of the two meson wavelet functions are determined according to the existing experimental data and we calculate the branching ratios and other physical observables.The main points are the following:(1)The PQCD predictions for the branching ratios of the considered quasi-two-body decays B ? D[R ?]KK are in the range of 10-9?10-7,while the branching ratios of B ?(?)[R ?]KK decays are more larger than them,between 10-7to 10-5in magnitude.The PQCD predictions for most considered decay channels agree well with currently available experimental measurements.(2)Under the narrow width approximation,we can extract the decay branch ratio of B0s?(?)0(f2(1270)?)K+K-),but we found large difference between our PQCD predictions with the extracted results.There are many possible reasons for such large deviation,which still need to be studied in the future.We also hope that the experimental groups make measurements for such decay processes.(3)The author calculated the decay channels of the S-wave,P-wave and D-wave resonant states in the three-body hadronic B/Bsdecays.Through the line graph of the ratio of the differential decay branch ratios to the constant mass,it can be obtained by comparison that the ?(1020)resonance state provides the largest contribution,while the f2(1270)state contributes the least.For those still unmeasured decay channels,we present our PQCD predictions and wish them to be measured in the near future.At present,the studies on the B meson three body(quasi-two-body)decay processes are still in their early stage,which is one of the hot topics in the field of heavy flavor physics.Theorists are constantly trying to improve the existing theoretical framework,and any theoretical breakthrough will receive widespread attention.LHCb and Belle-II experiments will also provide more and more experimental measurements for these decays in the forthcoming years,which will promote the development of the heavy flavor physics. |
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