The Calculation Of The Heavy To Light Semi-leptonic Decays Hadron Matrix In Light-cone QCD Sum Rules

The standard model of the particle physics has win great success,and it almost withstands all experiment test．At present,unresoved and unclear problems in standard model lies in Yukawa partsThis part is associated with flavour physics．The main problems ale the source and production mechanism of the CP violation．Therefore．accurate extraction of these parameters and testing CPviolation mechanism and finding new physics become hot topics in flavour physics research．The semi—leptonic decays B→πlv_l,has already been observed experimentally．Thisexclusive mode is considered to be very important to the determination of V_ab from transitionsb→u However,m．flyperfectresults Canonlybe expectedifthe calculationoftheformthctors canbe calculated accurately．In the calculation ofthe B mesons decay an^plimde,we inevitably will encounter all sorts ofhadron matrix．It is the fundmentaI and one ofthe most difficult problem in paticle physics．Becausetheir calculationinvolvesQCDpermrbative cffct．at present．itis difficulttO resolvethe problemfrom the first principles So we call use phcnomenological theory to study the decay ofthe ha&onsprocess．Current approaches include QCD factor,collinearity factor method,chiral perturbationtheory,heavy quark effectivetheory．quarkmodel,lattice calculations,pertubativeQCDmethod,QCD sum roles．and light-cone QCD sunl rolesIn this thesis,wemainlyfocus onthe application oflight—cone summlein studyingtheweakdecay ofB meson Because ofthe large uncertainty oftwist-3 light-cone distribution amplitudes,weadoptimproved correlationfunction byintroducing chiral currentto eliminatethe contributions ofthe twist一3 distribution ampfimdes．Then our sum mles will be more stable．we calcula[ed the B→πweak fonll faccorsf⁺．f^-.Their value is very important to investigate B meson decay process．and it is very important tO extract CKM matrix parameters．Because ofthe great uncertainty ofthe twist-3 distribution amplitude．the uncertainty of the fonn thctor is large．So we adopt chiral current to improve the correlation function,lhen WO remove the distribution ofthe twist一3 distribution amplitude．We have calculated the twist-2 terms and portnrbative corrections to the twist一2 terms with chiral current in the light-cone sum rule apprLoach．thenï¼›we,prcstnt tile results ofthe form factorsf+ f- apprLoach．then we present the results of the form factors f⁺,f^-...