Study Of The CP Violation For The Multi-body Decay Process Of B Meson In PQCD Approach

CP violation is an important area for testing the Standard Model and for finding new physical signals beyond the Standard Model,which has been explored theoretically and experimentally by scientists in recent years.Compared with numerous other mesons,the B meson provides an ideal platform for the study of the CP violation since it contains the b quarks which makes the perturbation approximation results better.And the study of the CP violation for the B meson has been extremely importance part in the research of particle physics over the past few years.In particular,the ratio of the tree-level amplitude to the penguin-level amplitude during the two-body decay of the B meson contributes the weak phase required for the CP violation.Besides,the scientists have given the relatively reliable theoretical predictions as well as experimental measurements after combining with the results of the factorization in theory.At present,the study of two-body decays of the B meson is well established and some results about it have also been given,including the CP violation and the branching ratios.In addition,the theoretical framework about the two-body decay process of the B meson with the final state mesons are PP,PV,VV has been developed,where P and V represent the scalar and vector mesons,respectively.At the same time,we find some resonance effects are associated with the new complex strong phase may also affect the CP violation during the decay process.Compared with the simple two-body decay process,the multi-body decay process contains more rich physical information.Hence,it is a great way for us to combine some resonance effect which will help us to better investigate the CP violation of the B meson.Therefore,we introduce the resonance effect of ρ0(ω,φ)and make a detailed analysis about it.We also derive the specific form of the mixing parameter under this mechanism.Then we take the method of the quasi-two-body decay process to explore the CP violation of the multi-body decay process,including the three-body and four-body decay process.We calculate the decay amplitude of the Bs→ρ0(ω,φ)η(’)→π+π-η(’)decay process after ignoring the high contribution under the resonance of ρ0(ω,φ).And then we make ta detailed analysis about the relationship between CP violation and the invariant mass.At last,we combine the data from the LHC experiment,which provides a new way to detect the CP violation under the resonance effect.In order to obtain an obvious CP violation which is easily detected on the experiment,we consider Bs→ρ0(ω,φ)ρ0(ω,φ)→π+π-π+π-four-body decay process.Since the decay process is a special pure annihilation decay process and the final state contains complex two vector mesons.Hence,we need to take the three polarization directions into account.Then we present the amplitude forms of Bs→ρ0ρ0→π+π-π+π-,Bs→ρ0ω→π+π-π+π-,Bs→ρ0φ→π+π-π+π-decay processes under the mixing mechanism and we can obtain the CP violation of these processes.Generally speaking,the degree CP violation of the pure annihilation decay process is tiny while we find the CP violation can enhance greatly when the invariant mass in the range of the ω and φ which even reach 78%.The study provides a excellent way to investigate the four-body decay of Bs meson and can be helpful clarifying the decay of vector mesons in the process of pure annihilation process.Finally,we also discuss the possibility of observing the CP violation of this decay process for BEPCII and the number of instances needed to observe our predicted CP violation for LHC.