PhD-defense國外博士論文答辯課件

1IdentifiedParticleProductioninp+pandd+AuCollisions

atRHICEnergiesFelixMatathiasDoctoralDefenseAdviser:TomHemmickStateUniversityofNewYorkatStonyBrookDecember8,2004,NewYork標(biāo)題添加點擊此處輸入相關(guān)文本內(nèi)容點擊此處輸入相關(guān)文本內(nèi)容總體概述點擊此處輸入相關(guān)文本內(nèi)容標(biāo)題添加點擊此處輸入相關(guān)文本內(nèi)容3ComparativeNuclearPhysicsYesterdayitoccurredtomethatthecoreconceptofmythesisisnotsodifferentthanwhatmywifedoesforaliving.MywifeisaPh.D.studentinComparativeLiteratureatStonyBrook.Igaveheracalllastnightandaskedherforashortdefinitionofherfield.SherepeatedlyaskedmywhyIneededitandseemedconfused(andconcerned).ThegoalofComparativeLiteratureis:“…tocompareliteratureindifferentlanguagesandliteraturewithrelationtosomeotherfield…”Inthatvein,IdefinethegoalofComparativeNuclearPhysicstobe:“…comparepropertiesofparticleproductionindifferentnuclearenvironmentsandasafunctionofparticleflavor…”O(jiān)bviouslythisisanarrowdefinitionthatImadeuptodefinethegoalofmythesis.Itcouldeasilythoughbeextendedtoamoregeneraldefinition.ThemainpointthoughisthatmywifemaybecomeinterestedinwhatIdo.4ComparativeNuclearPhysicsIIInthisworkwewillbecomparingparticleproductionatCenterofMassEnergy:√s=200GeVDifferentnuclearenvironments:p+pcollisionsd+AucollisionsAu+AucollisionsParticlespecies:pions,Kaons,(anti)protonsThephysicalobservableswillbeDifferentialyieldperinelasticcollisioninthed+AuandAu+AucaseInvariantdifferentialcrosssectionsinthep+pcase5Themachine

RelativisticHeavyIonColliderBrookhavenNationalLab2counter-circulatingrings3.834kmcircumferenceSuperconductingmagnets(3.5T)192dipolesperring246quadrupolesperringTimebetweencollisions:0.213microsecondsCrossingangle:0Bunchlength:20cmBunchesperring:56Luminositylifetime:3-10hoursParticlesperbunch(units1010):Au+Au:0.1p+p:10Topenergies(eachbeam):100GeV/nucleonAu+Au.100GeV/nucleond+Au100GeVpolarizedp+p6ThedetectorMaximalSetofObservablesPhotons,Electrons,Muons,ID-hadronsHighlySelectiveTriggeringHighRateCapability.RareProcesses.Butrareprocessesalwayscomelateinthegameforcolliderexperimentsduetolimitedluminosity.ButIwantedathesisatsomepoint.ThereforeIutilizethecopiousproductionofhadrons,throughthestrongnuclearforce,albeitwitharelativelysmalldetector.7Doesnuclearsizematter?

(Yes,butinmysteriousways)Comparingparticleproductionindifferentnuclearenvironmentswouldn’tbethatinterestingifeverythingscaledaccordingtothesizeofthecollidingsystemDefinitionofpoint-likescaling:.Dowealreadyknowanythingaboutthescalingpropertiesofhardscattering?Answer:Yes,weknowthatscalingisstronglyviolated!8ColdNuclearMatterEffects:

the“InitialState”9CroninEffectInp+Acollisions:ParameterizationdonebyCroninetal.(Phys.Rev.D11,3105,1975)Alphafactorsare:pt-dependentspecies-dependentCronineffectEnhancementathigh-ptShadowingatlow-ptMechanism:InitialpartonmultiplescatteringAntreasyanet.al.Phys.Rev.D19(3)1979Straubet.alPhys.Rev.Lett.68(4)1992Questionsthatthisthesiswillanswer:WhatisthesizeoftheCronineffectatRHICenergies?Whatisthespecies-dependenceoftheCronineffectatRHICenergies?WhatistheenergydependenceoftheCronineffectatRHICenergiescomparedtoFermilabobservations?10PartonSaturationLinearevolution(DGLAP)leadstoviolationofunitarity.Atsomepoint,thepartondensityacquiresanegativeterm:11Theonsetofpartonsaturation“Packing”factorOnsetofsaturation:k~1Solutioninthex-Qplane.Saturationmoment:Thescaleatwhichnon-lineareffectsstarttobeimportantinthehadronwavefunction.ForQ>>Q_saturation(t)non-lineareffectsarenegligibleandlinearevolutioneffectsapply(BFKL,DGLAP)12Theneteffectofpartonsaturationisparticlesuppression.dASaturated

nuclear

wavefunctionNon-saturated

deuteron

wavefunction“Cronin”“Suppressed”Thisthesisanswersthequestion:enhancementorsuppresionforidentifiedparticles?Phys.Let.B561,93(2003)13HotandDenseNuclearMatterEffects:

theFinalState14AnewstateofmatterHypothesis:hadronicmatterundergoesaphasetransitionastemperaturereachesT~170MeVSupportedbythedecreaseofthestrongcouplingconstantasafunctionofenergy.Energydensityincreasesoveranorderofmagnitudeinanarrowrangeoftemperatures10-20MeVLatticeQCDprovidesthemostquantitavetheoreticalsupporttothisday.F.Karsch,Lect.Notes.Phys583,209(2002)Understandingthetransitionasachangeofthenumberofdegreesoffreedom:BelowTc:dilutegasof3statesofpionsAboveTc:for2flavorswehave2(flavors)x2(quark,antiquark)x2(spinstates)x3(colors)=24quarkd.o.f.8(colorsofgluons)x2(helicityd.o.f.)=16gluonicd.o.f.15AnewStateofMatterIIThequarkandgluondegreesoffreedomnormallyconfinedwithinhadronsaremostlyliberatedThetransitionoccurswhentheenergydensityofmatterisoftheorderofthatofmatterinsideaprotonEnergydensityaboutanorderofmagnitudelargerthantheenergydensityinsideatomicnuclei:1-10GeV/fm3Formationtimet0=0.3-1fm/c

i~5-15GeV/fm3Tc~250-350MeV

Wecandothis!Au+AucollisionsatRHICpushmatterattheseextremesroutinely.16Theobservableofthedayisagain…..Scenario1:RAA=1:Scalewith#ofbinarycollisions(Ncoll).Scenario2:RAA>1:Cronineffect(observedinISRandSPS).Scenario3:RAA<1:Suppression.<Nbinary>/sinelp+p

NuclearModificationFactorNNcrosssection17SuppressionofhighptparticlesCentralRAAsuppressedbyfactorof4.5qqhadronsleadingparticlejetproductioninquarkmatterMediuminducedenergylossinsidethemediumPredominantlyviagluonbrehmstrahlungemmisionOr,partonsaturation?Thisquestionisansweredinthisthesisforidentifiedparticles.18Butthereismoretoit…..Thesuppressionpatternseemstobestronglydependentonparticleflavor.Counterintuitive.Ifpartonsfromhardscatteringarelosingenergyinthemedium,shouldn’tthatreflecttoallparticlesproduced?Ncollscalingatallcentralitiesfortheprotons.Aquestionthatthisthesiswillanswer:CouldahigherCronineffectfortheprotonsexplainthiseffect?Notice:R_CPnotR_AA19Furthermore….Ananomalouslyhighprotontopionratiowasobserved.Aspectacularobservationthathadnotbeenpredicted.Lighterpionsarefavoredduetophasespacepopulation.Fragmentationfunctionsfromelementaryp+pande+ecollisionsseemtobechangedinsidethemedium.Whatistheextrasourceofprotons?Aquestionthatthisthesiswillanswer:Whatarethevaluesoftheseratiosinelementaryp+pandd+Aucollisionsatthesameenergy?20Bestof

PIDAnalysisinp+pandd+Aucollisions.

21ChargedHadronPIDAnalysisDetectorsforhadronPIDDCH+PC1+TOF+BBCDf=p/8,-0.35<h<0.35MomentumResolutionTOFresolutionsTOF~130ps.HadronPIDinm2vs.pspacewithasymmetricPIDcuts.0.2<p<3.0GeV/c,0.4<K<2.0GeV/c,0.6<p<3.7GeV/c.22PIDwithBBC+TOF+DCH:

TimingcalilbrationsTimingCalibrations:SlatbySlatRunbyRunGlobaltimingoffsets23PIDwithBBC+TOF+DCHClearseparationofparticlesuptohighpt.Stableperformanceinp+pandd+AucollisionsThep+pandd+AudataarebothfromRHICRUN03andthereforedetectoreffectsaresmallinmostratiosofp+pandd+Audata.24PIDcutsWidthofcuts3parametersimultaneousfittomasswidthsforallparticlesParameterizationofcutsinGaussianwidths,independentofmomentum25VerificationofPIDcutsparameterizations26DetectoracceptanceandefficiencycorrectionsDetectoracceptancesisstudiedindetailHolesareremovedbycutsIndependentstudiesfor:Positive/negativeparticlesDCHandTOFdetectorsNorthandSouthsidesDetectorareasofmaximumefficiencyarecomparedtoMonteCarlosimulationandefficiencycorrectionsfortheentiredetectoristhencalculated.27MatchingandfiducialcutsGoldenFiducialcutsResidualdistributionbetweenTOFhitandtrackmodelprojection.Distributionsarefittedasafunctionofmomentumforpositive/negativeparticles,forNorth/Southpartofthedetector28DetectorStability:ExcerptsAntiproton/protonvs.RunNumberPIDcutsvs.RunNumberNumberoftracksvs.RunNumberAcceptancevs.RunNumber29MonteCarloCorrectionsSincePhenixdoesnotcoverfullacceptanceinphiandzedweuseMonteCarloSimulationtocorrectforgeometricalacceptance.Alsoinflightdecaysarecorrectedfor.FinallyallcutsusedinrealanalysisarealsousedinMonteCarloanalysisandthereforetheefficiencyofthecutsarethuscalculated30SystematicerrorsSystematicerrorevaluationisdonebyvaryingcutconditionsintheanalysisby1s,2s,etc.Additionalsystematicvariationsare:Run-by-runvariations~5%Efficiencycorrections~3%Feed-downcorrections~10%InadditiontheBBCcrosssectionintroducesa10%systematicerroronp+pcrosssections.TYPE-B:Momentumcorrelated,allpointsmoveinthesamedirectionbutnotbythesamefactorTYPE-C:Momentumindependentp+pType-C:31Feed-downcorrectionsAsignificantfractionofprotonsandantiprotonsdetectedbytheTOForiginatefromweakdecaysof:HyperonsY(qqs)CascadesX(qss)OmegasW(sss)Sincetheweakdecaystakeplaceveryclosetothevertex,andsincetheheavierprotonstakemostofthedecaymomentum,thesetracksarevirtuallyindistinguishablefromtracksarisingfromthevertexofthecollision.TotalprotonsdetectedbyTOF:ParticlecompositionfromUA5in200GeVp+pbarcollisions32eeInputLSpectrainp+pandd+AufrompreliminarySTARresultsandUA5ConstructionofeffectiveLSpectrumwhichthenisdecayedinPHENIX33Feed-downcorrectionsCorrectionisoftheorderof30%forprotonsandantiprotons.UsingthepreliminaryAntilambda/Lambdaratio0.85+/-10%fromSTARweapplycorrespondingcorrectionstoprotonsandantiprotons.Largesystematicerroronthefeed-downprotonsarisesfromlargeUA5systematicsandpreliminaryStarresultsSystematicerror~24%34Centralitydeterminationind+AuCentralitydeterminationind+AuisdonewiththeSouthBBC(Au-side).Assumption:BBCsignalisproportionaltoparticipatingAunucleons.GlauberModelcalculationandBBCsimulationresponse,maptheBBCSsignaltoimpactparameterdistributions.CorrespondingNcolldistributionsind+Auarethenusedtodefinethenuclearmodificationfactors.35Results36I.Spectra37Pions38Kaons39Protons40d+AuMinBias41p+pinvariantcrosssections42II.Ratios43Antimatter/matterd+Au+Systematics44Antimatter/matter:p+p45Antimatter/matter:p+p,d+Au46Antimatter/matter:p+p,d+Au,Au+Auperipheral47Antimatter/matter:AllcollisionsystemsWithintheerrors,allratiosareflatandindependentofcollisionsystem!Astonishingresultsincethemicroscopicmechanismforparticleproductioninp+pandcentralAu+Aucollisionsisfundamentallydifferent.48Nocentralitydependencewithind+Au49p/pinallsystemsReturnoftheratiotonormalvalues.SmoothtransitionfromcentraltoperipheralAu+Aucollisions.d+AuissimilartothemostperipheralAu+Aubin.p+pislowerthand+Au,duetolargeCroninforprotons“Whoorderedthat?”“Certainlynotp+pnord+Au.”50p/pinp+pandd+AuModeratecentralitydependenceind+Au.p+pcollisionsarelower.51III.NuclearModificationFactors52RdAuMinimumBiasNosuppression.WeestablishthesizeofCronineffectatRHICenergies.SpeciesdependenceofCroninissignificant.Aswewillseeinthefollowing,CronineffectforprotonsisnotlargeenoughtojustifyAu+Aubehavior.Protons:~40%enhancementPions:~10%enhancement53RdAu00-20%Stillaround10-15%enhancement~60%enhancement54RdAu20-40%55RdAu40-60%56RdAu60-90%Binaryscalinginperipheralcollisions.57PionRCPfrom3differentdetectors:

CronineffectdissapearsathighptChargedpionsfromTOF.NeutralpionsfromEMCAL.ChargedpionsfromRICH+EMCAL.Niceagreement.Cronineffectforpionssaturatesatpt~8GeV/c58NuclearModificationfactorsinAu+Aucollisions.59RAuAuofidentifiedparticles:0-5%60RAuAu0-5%withneutralpions61RAuAu0-5%withneutralpionsSuppressedbyfactorof~5RAuAu~1.25Pionsuppressionbyafactorof~6relativetotheprotonsSpeciesdependenceofCronineffectind+Aunotmorethan35%62RAuAuofidentifiedparticles:60-92%

63RAuAu60-92%withneutralpions64Comparison:RAuAuvs.RdAu65EnergyDependenceUsingmodestassumptionswecancalculateRdAuatlowerenergies.Usethealpha-factorsmeasuredbyStraubetal.ComparewithRdAuatRHICenergies.LowEnergyDatafrom:Phys.Rev.Lett.68452,1992InclusiveChargedandNeutralPiondataprovethattheCronineffectfortheprotonsissignificantlyloweratRHICenergies.66OpposingTheoreticalModelsfortheCroninEffect67Accardi-Gyulassy

Phys.Lett.B586,244(2004)Glauber-Eikonalformalism.Calculationofseriesdirectlyvianumericalconvolutionofelementaryparton-nucleonprocesses.Parameters:p0=1.0GeV,infraredcutoff,establishedfromfittingp+pdataIntrinsic<kt>=0.52GeV2,establishedfromfittingp+pdataK=1Allrenormalizationscalessettomt/2Theoreticalerrorfromvaryingcut-offvalue.Noadditionalshadowingisaddedbyhand.Ifthismechanismisbelowtheexperimentaldatathenpartonsaturationscenariosmaybeneededtoexplainthedata.68RdAu00-20%Reasonableagreementwiththedata.Noneedforadditionalsaturationscenarios.Centralitydependenceisreproduced.ColorGlasspredictionfromKharzeev,LevinandMcLerranisalsoshown.Theoreticalcalculationbecomesunreliablebelowthecut-offvalue.Phys.Let.B561,93(2003)69RdAu20-40%70RdAu40-60%71RdAu60-90%72CroninEffectasaFinalStateInteractionEffect.

RecombinationbyHwa&Yang

73TheHwa-Yangprogram

(OregonGroup)Clusteringandhadronizationofquarks:Atreatmentofthelow-ptproblemPhys.Rev.DVolume22,p.1593,1980PartonDistributionsintheValonModelhep-ph/0202140RecombinationModelforFragmentationhep-ph/0312271RecombinationofshowerpartonsathighptinHeavyIoncollisionsnucl-th/0401001FinalStateInteractionastheoriginofCronineffectnucl-th/040300174RecombinationmodelforFragmentationAhardpartonwithhighvirtualityinitiatesapartonshowerthroughgluonradiationandpaircreation.Nonperturbativeprocess.Thefragmentationfunction(FF)canbewrittenintermsoftheshowerpartondistributions(SPD)andtherecombinationfunction(RF).UsethemeasuredFFs.SolvetheequationfortheSPDs.UsetheSPDsindifferentenvironments(d+Au,Au+Au).75RecombinationofShowerPartonsinHeavyIonCollisions:

ThermalandShowercomponentsFirstapplicationofSPDoutsidetherealmofpartonfragmentation.Startwiththemesonproduction.Fixalltheparameters.Calculatetheprotonproduction.Deriveprotontopionratio.ThermalThermal+ShowerFragmentation(onejet)Differentjets.low-ptmoderate-pthigh-ptNegligible76ResultforpionsandprotonsinAu+Au.Theprotonspectrumisreallyapredictionofthemodel.77Thenextstep:d+Au

FinalStateInteractionastheOriginofCroninEffect.Nobroadeningbysuccessivekicks.Noenergyloss.Thermal-Showerrecombinationisresponsiblefortheenhancementatintermediatept.Interactionbetweensoftandshowerpartons.Softcomponentisnotthepredictablepartofthemodel,requiresfittingtogetCandT.ThemagnitudeoftheTStermistheprediction.78RCPforpionsandhigherCroninforprotonsind+Au.SpectraandRcpforpions.Protontermwillhave:TTT+TTS+TSS+SSS+…FirstshotatexplainingthehigherCroninforbaryons.

79FirstExplanationofCroninEffectforprotonsind+Au.Goodagreementwiththed+Audata.Thisradicalinterpretationofthedataintroducesareinterpretationofparticleproductionwithfarreachingconsequences.Separationofpartonsintotwonon-interactingcomponents,softandhard,isanoversimplification.PROTONPRODUCTIONIND+AUCOLLISIONSANDTHECRONINEFFECT.

ByR.C.Hwa(OregonU.)andC.B.Yang(OregonU.andHua-ZhongNormalU.)Apr2004.4pp.

PublishedinPhys.Rev.C70:037901,2004

e-PrintArchive:nucl-th/040406680ConclusionsandPerspectiveWehaveestablishedtheinitialconditionsofidentifiedparticleproductionatRHICenergiesthroughadetailedstudyofp+pandd+Aucollisions.ThroughthesemeasurementsweconcludeontheoriginofsomeoftheanomalousresultsdiscoveredincentralAu+Aucollisions.InanutshellweprovedthatallthesespectaculareffectsareFINALSTATEEFFECTSandhavenothingtodowithinitialstateconditions.Wealsoperformedadetailedstudyofthecoldnuclearmattereffectsarisingfromd+Aucollisions.Furtherstudiesofjetpropertiesofidentifiedparticleswillshedmorelightintherealmicroscopicmechanismresponsibleforparticleproductioninhotanddensenuclearmatter.81TheFutureThed+Audatapresentedtodayaregoingtobepublishedintheupcomingweek.ApaperonComparativeNuclearPhysi