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1、CLNS00/1660January2000hep-ph/0001334IntroductiontoBPhysicsMatthiasNeubertNewmanLaboratoryofNuclearStudies,CornellUniversityIthaca,NewYork14853,USAAbstract:Theselecturesprovideanintroductiontovarioustopicsinheavy-
avorphysics.Wereviewthetheoryandphenomenologyofheavy-quark
2、symmetry,exclusiveweakdecaysofBmesons,inclusivede-cayrates,andsomerareBdecays.arXiv:hep-ph/0001334v131Jan2000LecturespresentedattheTriesteSummerSchoolinParticlePhysics(PartII)Trieste,Italy,21June{9July,1999INTRODUCTIONTOBPHYSICSMATTHIASNEUBERTNewmanLaboratoryofNuclearStu
3、diesCornellUniversity,Ithaca,NY14853,USATheselecturesprovideanintroductiontovarioustopicsinheavy-
avorphysics.Wereviewthetheoryandphenomenologyofheavy-quarksymmetry,exclusiveweakdecaysofBmesons,inclusivedecayrates,andsomerareBdecays.1IntroductionTherichphenomenologyofwea
4、kdecayshasalwaysbeenasourceofinforma-tionaboutthenatureofelementaryparticleinteractions.Alongtimeago,-and-decayexperimentsrevealedthestructureoftheeective
avor-changinginteractionsatlowmomentumtransfer.Today,weakdecaysofhadronscon-tainingheavyquarksareemployedfortestso
5、ftheStandardModelandmea-surementsofitsparameters.Inparticular,theyoerthemostdirectwaytodeterminetheweakmixingangles,totesttheunitarityoftheCabibbo-Kobayashi-Maskawa(CKM)matrix,andtoexplorethephysicsofCPviolation.Hopefully,thiswillprovidesomehintsaboutNewPhysicsbeyondthe
6、Stan-dardModel.Ontheotherhand,hadronicweakdecaysalsoserveasaprobeofthatpartofstrong-interactionphenomenologywhichisleastunderstood:theconnementofquarksandgluonsinsidehadrons.ThestructureofweakinteractionsintheStandardModelisrathersimple.Flavor-changingdecaysaremediatedb
7、ythecouplingofthechargedcurrentJtotheW-bosoneld:CCgyLCC= pJCCW+h.c.,(1)2where0101eLdLJ=(;;)@A+(u;c;t)V@sA(2)CCeLLLLCKMLLbLcontainstheleft-handedleptonandquarkelds,and01VudVusVubVCKM=@VcdVcsVcbA(3)VtdVtsVtb1istheCKMmatrix.Atlowenergies,thecharged-curr
8、entinteractiongivesrisetolocalfour-fermioncouplingsoftheformpyLe= 22GFJCCJCC;;(4)whereg2p 2GF==1:166