Exclusive B?sl~+l~- Decays Within The Two Higgs Doublet Model

The standard model of particle physics describes the properties,motion,interaction and transformation of the smallest particles in nature.It mainly consists of two parts:strong interac-tion and electroweak interaction.At present,its prediction results withstand the test of almost all high-energy physics experiments.However,it is not perfect and graceful.The most direct reason is that it does not contain gravitational interactions in general relativity.In addition,It does not include dark matter,dark energy and neutrino mass.For these reasons,there have been a great deal of work in the search for new physics beyond the standard model,both theoretically and experimentally.This is must face the challenge of the further development of particle physics.For finding new physics in high energy scale region(higher than the electroweak scale?EW(?)246GeV),in addition to the direct detection of new heavy elementary particles from the experiment,it can also be found indirectly by means of low-energy processes in flavor physics.The physical processes that are strongly suppressed in the standard model have been proved to be effective in search for new physics,such as the flavour changing neutral current(FCNC)processes.In this paper,we first introduce some possible signs of the new physics in the rare decay processes b?sl+l-observed in recent experiments.These processes mainly include the so-called P5' anomaly in B?K*?+?-decay,the lepton flavor universality violation in B+?K+l+l-decay,and the branching fraction in Bs0???+?-decay,and so on.Then,we briefly introduce the QCD,the electroweak theory,and the Higgs mechanism in the standard model,the low-energy effective Hamiltonian method in dealing with the heavy flavor physics problems,and the new physics model-two Higgs doublet model.Then,the method of dealing with the continuous bound state problem is introduced,called Dyson-Schwinger equation.After that,the main part of this dissertation is divided into two parts:The Wilson coefficients of rare decay b?sl+l-within the new physics In the aligned two-Higgs-doublet model(A2HDM),we give a complete one-loop computation of the short-distance Wilson coefficients C7,9,10,(')which are the most relevant ones for b?sl+l-transitions.We find that when the model parameter |?u|is far less than |?d|,the charged-scalar contributes mainly to chirality-flipped operators(?)9,10' and the corresponding new physical Wil-son coefficient C9,10'H± is proportional to |?d|2.Using the inclusive radiative decay B?Xs? and the most recent model-independent global fit of b?sl+l-data,we restrict the Wilson coef-ficient C7,9,10,(')H± and then obtain the parameter space of the new physical model parameters.In the allowed parameter space,we find that the Wilson coefficient C7,9,10,(')H± can be divided into two categories,numerically,(A)C7,9,10,(')H± are sizable,but C7,9,10,(')H±(?)0;(B)C7H± and C9,10,'H± are sizable,but C9,10H±(?)0,corresponding to the(large |?u|,small |?d|)region and the(small |?u|,large |?d|)region,respectively.It shows that in the aligned two-Higgs-doublet model,the charged-scalar can not affect the left-and right-semileptonic operators on the same time.The effect of new physics on angular distribution of B?K*?+?-and Ab??(? p?-)?+?-The abnormal phenomena in mesonic b?sl+l-decay can be explained through the shift ?C9(?)-1,but the corresponding baryonic decay prefers a pos-itive shift to C9.This suggests that the b-hadron physics process cannot be explained solely by changing the C9.In B?K*?+?-decay,we find that there is only a small influence on P2 and P5',both in case A aligned two-Higgs-doublet model and the four natural flavour conservation two-Higgs-doublet model,and does not help to explain the anomalies.But case B can provide a larger P5' so that it is consistent with the experimental data.For the ?b???+/?-process,we calculate all the angular observables both in the standard model and the two-Higgs-doublet model.For the ?b?? transition form factors,we use the recently high-precision lattice QCD results.We find also in case B,the aligned two-Higgs-doublet model can evidently improve the differential branching ratio and the lepton-side forward-backward asymmetry in the bin ranges[15,20]GeV2,and compatible with the experimental data at 0.2 ? and 1.3?,respectively.There-fore,we argue that the aligned two-Higgs-doublet model in case B is a very likely explanation for the experimentally observed anomalies in the b-hadronic decay.In the future,the more accurate measurement of experiments,especially with a finer binning of q2,will help us to understand the process of b?sl+l-more clearly.Currently,some experi-mental results of the measurement of lepton flavor non-universality,such as RK,Q5,R(D)and R(D*)are also very interesting.Further research is needed in the future,both experimentally and theoretically.