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Theb-physicsresultsfromtheLEPdatasetsexceededallexpectationsinboththe range of topics covered and the precision of measurements that were eventually possible. Thesuccesswasduetoseveralfactorssuchastherapiddevelopmentof silicon-strip vertex detectors, advances in the theoretical description of b-hadrons and not least because of the inventiveness, skill and determination of the expe- mentersperformingthedataanalysis. Inordertoutilisefullytheprecisionofthe newvertexdetectors,carefulcommissioningandeventreconstructionwasneeded. Thistogetherwithnewmethodsandtechniquesofdataanalysis,particularlyinthe areaofinclusiveb-hadronreconstruction,werethekeytoawholehostofmeasu- mentsthatspannedtheentire?eldofb-physics. Theaimofthisbookisnottogiveanotherreviewofb-physicsresults. Instead the focus is on reviewing the main experimental methods that evolved (hardware andsoftware)andthelessonslearntfromsomebodywhowasinvolved?rst-handin theirdevelopmentanduse. Thehopeisthatthisworkwillbothstandasarecordof whatwasachievedwiththeLEPdata,andalsoasareferencesourceofb-physics analysisideasforexperimentersembarkingonprojectsinthefuturee. g. attheLHC oralinearcollider. ResultsfromallfouroftheLEPexperimentsarereportedbutsomebiastowards DELPHIisinevitable,especiallytoillustrategeneralpoints,sinceIamacolla- rationmemberandhaveeasieraccesstomaterial. Iwishtothankmyfriendsand colleaguesoftheDELPHIcollaborationformakingtheprojectsuchasuccess. InadditionIwishtogivespecialthanksto:Prof. Dr. MichaelFeindtwhowasthe instigatorofinclusiveanalysismethodsforb-physicswiththeLEPdata;Prof. Dr ThomasMullerforgivingmetheopportunityandencouragementtowritethisar- cle;Dr. RichardHawkings(OPAL)andDr. ChristianWeiser(DELPHI)forallowing meaccesstosomeunpublishedresultsandforusefuldiscussions. FinallyIwould liketothankthepeopleatSpringer,especiallyUteHeuserforherprofessionalh- dlingoftheprojectandpatiencewithmyregularfailuretomeetdeadlines. UniversityofWarwick,UK GaryJ. Barker September2009 vii Contents 1 b-physics at LEP …1 1. 1 Introduction …1 1. 2 TheLEPMachineandExperiments …3 1. 3 b-PhysicsOverview…4 1. 3. 1 b-QuarkProduction…7 b 1. 3. 2 Forward-BackwardAsymmetry A …7 FB 1. 3. 3 R …9 b 1. 3. 4 HeavyQuarkSymmetry…10 1. 3. 5 b-QuarkFragmentation…10 1. 3. 6 b-HadronSpectroscopy …12 1. 3. 7 b-HadronProductionFractions…13 1. 3. 8 Weakb-QuarkDecay…1 3 1. 4 Combiningb-PhysicsResults…18 1. 4. 1 AveragingofElectroweakHeavyFlavourQuantities…19 1. 4. 2 AveragingofNon-electroweakHeavyFlavourQuantities…20 References …20 2 Silicon Vertex Detectors and Particle Identi?cation …23 2. 1 Silicon-StripVertexDetectors …23 2. 2 ParticleIdenti?cation…29 2. 2. 1 Speci?cIonisationEnergyLoss,dE/dx …30 ? 2. 2. 2 CerenkovRingImaging …31 2. 2. 3 OverallDetectorPerformance …32 References …34 0 ~ 3 Experience in Reconstructing Z ? bb Events…37 3. 1 ImpactParameterandDecayLength …37 3. 1. 1 ClusterFinding …40 3. 1. 2 TrackFittingandPatternRecognition …41 3. 1. 3 VertexDetectorAlignment…43 3. 1. 4 SingleHitUncertainties…49 3. 1. 5 ResolutionTuning …
