SomeSome IssuesIssues inin CharmoniumCharmonium ExclusiveExclusive ProductionProduction andand DecaysDecays
CongCong--FengFeng QiaoQiao GraduateGraduate UniversityUniversity ChineseChinese AcademyAcademy ofof SciencesSciences
MayMay 1919，，20102010
QWG7 Fermilab, 2010 CONG-FENG QIAO 1 ContentsContents
•• PolarizedPolarized J/J/ΨΨ PairPair ProductionProduction atat thethe LHCLHC
•• ηb ExclusiveExclusive DecaysDecays toto J/J/ΨΨ PairPair
•• ηc ExclusiveExclusive DecaysDecays toto VectorVector MesonMeson PairPair
•• BriefBrief SummarySummary
QWG7 Fermilab, 2010 CONG-FENG QIAO 2 I.I. PolarizedPolarized J/J/ΨΨ PairPair ProductionProduction atat thethe LHCLHC zz ColorColor--singletsinglet modelmodel mademade aa successfulsuccessful descriptiondescription ofof heavyheavy quarkoniumquarkonium productionproduction andand decaysdecays [Wise, 1980; Chang, 1980; Berger & Jones, 1981; …] zz However,However, itsits leadingleading orderorder resultresult isis challengedchallenged byby somesome experimentalexperimental datadata zz InIn phenomenology,phenomenology, nonnon--relativisticrelativistic QCDQCD basedbased ColorColor--octetoctet mechanismmechanism improvesimproves thethe theoreticaltheoretical resultsresults greatlygreatly inin severalseveral casescases
QWG7 Fermilab, 2010 CONG-FENG QIAO 3 z Recently, the NLO QCD calculations in CSM significantly enhance the color-singlet yield in lots of charmonium production processes, and hence diminish the estimated color-octet contributions [Chao et aal.,l., 2006, 2007, 2010; Wang et al., 2007 2008, 2010; Artoisenet, et al., 2007; …] z In some cases, the higher order calculations in CSM can even explain the data
z The application of COM to charmonium physics keeps on being a debatable issue
QWG7 Fermilab, 2010 CONG-FENG QIAO 4 zzInIn all,all, toto whatwhat degreedegree thethe colorcolor--octetoctet mechanismmechanism playsplays thethe rolerole inin quarkoniumquarkonium productionproduction isis stillstill anan unsettled,unsettled, urgenturgent andand interestinginteresting questionquestion
QWG7 Fermilab, 2010 CONG-FENG QIAO 5 3 zzTheThe J/J/ΨΨ fromfrom colorcolor--octetoctet statestate SS1 atat thethe leadingleading orderorder ofof strongstrong couplingcoupling constant,constant, areare mostlymostly transverselytransversely polarizedpolarized
QWG7 Fermilab, 2010 CONG-FENG QIAO 6 zzHigherHigher orderorder correctionscorrections toto colorcolor--octetoctet statestate 3 8 SS1 productionproduction andand thethe effecteffect ofof colorcolor--octetoctet 1 8 3 8 statesstates SS0 andand PPJ maymay yieldyield somesome longitudinallylongitudinally polarizedpolarized charmoniumcharmonium [Beneke and Rothstein 1996; Braaten, Kniehl and lee, 2000] zzPredictingPredicting thethe J/J/ΨΨ polarizationpolarization inin inclusiveinclusive productionproduction isis impairedimpaired inin certaincertain degreedegree byby thethe largelarge higherhigher orderorder correctionscorrections
QWG7 Fermilab, 2010 CONG-FENG QIAO 7 QWG7 Fermilab, 2010 CONG-FENG QIAO 8 zzInIn exclusiveexclusive processprocess thethe higherhigher orderorder contributionscontributions areare relativelyrelatively suppressedsuppressed
zzTherefore,Therefore, toto measuremeasure thethe J/J/ΨΨ pairpair productionproduction atat thethe LHCLHC isis possiblypossibly aa feasiblefeasible wayway toto detectdetect thethe charmoniumcharmonium productionproduction mechanismmechanism
QWG7 Fermilab, 2010 CONG-FENG QIAO 9 AsAs thethe LHCLHC withwith zzTheThe luminosityluminosity :: 101032 __ 101032 cmcm-2/s/s zzCenterCenter massmass ofof energy:energy: 77 __ 1010 __ 1414 TeVTeV zzTheThe pseudorapiditypseudorapidity :: ηη << 2.22.2
QWG7 Fermilab, 2010 CONG-FENG QIAO 10 zzTheThe polarizedpolarized J/J/ΨΨ pairpair hadroproductionhadroproduction isis estimatedestimated [Barger et al. 1996; CFQ 2002; Li, Zhang and Chao 2009; Sun, Sun and QCF 2010] zzBothBoth thethe colorcolor--singletsinglet andand colorcolor--octetoctet effectseffects areare considered,considered, atat thethe leadingleading orderorder ofof strongstrong couplingcoupling constantconstant
QWG7 Fermilab, 2010 CONG-FENG QIAO 11 Fock State Configuration of the J/Ψ pair
QWG7 Fermilab, 2010 CONG-FENG QIAO 12 TheThe typicaltypical FeynmanFeynman diagramsdiagrams inin colorcolor singletsinglet casecase
QWG7 Fermilab, 2010 CONG-FENG QIAO 13 InIn colorcolor octetoctet casecase
QWG7 Fermilab, 2010 CONG-FENG QIAO 14 WithWith InputInput parametersparameters
QWG7 Fermilab, 2010 CONG-FENG QIAO 15 TheThe integratedintegrated crosscross sectionssections ofof J/J/ΨΨ pairpair productionproduction inin colorcolor--singletsinglet modelmodel
QWG7 Fermilab, 2010 CONG-FENG QIAO 16 TheThe integratedintegrated crosscross sectionssections ofof J/J/ΨΨ pairpair productionproduction inin colorcolor--octetoctet modelmodel
QWG7 Fermilab, 2010 CONG-FENG QIAO 17 TheThe differentialdifferential crosscross--sectionsection ofof J/J/ΨΨpairpair productionproduction versusversus ppT atat thethe LHCLHC inin CSMCSM
a , b , c represent ^^ , || || , || ^, respectively
QWG7 Fermilab, 2010 CONG-FENG QIAO 18 TheThe differentialdifferential crosscross--sectionsection ofof J/J/ΨΨpairpair productionproduction versusversus ppT atat thethe LHCLHC inin COMCOM
a , b , c represent ^^ , || || , || ^, respectively
QWG7 Fermilab, 2010 CONG-FENG QIAO 19 TheThe resultsresults show:show: •• ForFor thethe casecase ofof collidingcolliding energyenergy upup toto 1010 TeVTeV andand luminosityluminosity 1fb^1fb^--11 ,, thethe datadata withwith atat leastleast oneone J/J/ΨΨ inin aa pairpair beingbeing longitudinallylongitudinally polarizedpolarized areare aboutabout fiftyfifty percentpercent ofof thethe totaltotal yieldyield withwith thethe lowerlower transversetransverse momentummomentum boundbound ofof 55 GeVGeV •• InIn thethe pairpair production,production, bothboth colorcolor--singletsinglet andand -- octetoctet schemesschemes exhibitexhibit thatthat thethe J/J/ΨΨ shouldshould bebe dominateddominated byby thethe transverselytransversely polarizedpolarized yieldyield inin largelarge transversetransverse momentummomentum regionregion
QWG7 Fermilab, 2010 CONG-FENG QIAO 20 II.II. η b ExclusiveExclusive DecaysDecays toto J/J/ΨΨ PairPair
zz TheThe lowestlowest energyenergy statestate inin ΥΥ family,family, thethe η b ,, isis veryvery elusiveelusive zz AboutAbout thirtythirty yearyear afterafter itit spinspin triplettriplet partnerpartner beingbeing found,found, recentlyrecently itit waswas observedobserved forfor thethe firstfirst timetime
byby BabarBabar throughthrough ΥΥ (3s)(3s) ---->> η b γγ
[Aubert, et al., Babar Collaboration, 2008]
QWG7 Fermilab, 2010 CONG-FENG QIAO 21 TheThe bottomoniumbottomonium energyenergy levellevel spectrumspectrum (CLEO Collaboration July 19, 2002) TheThe experimentalexperimental searchsearch forfor ηb
TheThe existenceexistence ofof thethe η b isis aa solidsolid predictionprediction ofof thethe quarkquark modelmodel
InIn recentrecent years,years, thethe searchsearch forfor η b hashas beenbeen conductedconducted atat CLEO,CLEO, LEP,LEP, andand CDF,CDF, BB--factories,factories, usingusing bothboth inclusiveinclusive andand exclusiveexclusive methodsmethods SearchSearch η b atat CDFCDF [Tseng, CDF, 2002] zz ηb ÆÆJ/J/ψψ J/J/ψψ zz AA smallsmall clustercluster ofof 77 eventsevents cancan bebe seen,seen, wherewhere 1.81.8 eventsevents areare expectedexpected fromfrom backgroundbackground zz IfIf thisthis clustercluster isis duedue toto η b decay,decay, thenthen thethe productproduct ofof itsits productionproduction crosscross--sectionsection andand decaydecay branchingbranching fractionsfractions areare nearnear thethe lowerlower limitlimit ofof expectationexpectation fromfrom BraatenBraaten etet al.al. zz AccordingAccording BraatenBraaten,, FlemingFleming andand LeibocichLeibocich (hep(hep--ph/0008091)ph/0008091) ,, thoughthough helicityhelicity suppressed,suppressed,
−35− B r[ηψψb →+ J / J / ] =×× 7 10 ~7 10 zz WhichWhich seemsseems toto bebe overestimated,overestimated, sincesince
−5 Br[ηb →+++ CCCC]~10
[Maltoni and Polosa,hep-ph/0405082] zz AA recentrecent analysisanalysis shows:shows: [Y.Jia, hep-ph/0611130]
−9 Br [ηφφb →+ ] ≈ ( 0.9 − 1.4 ) × 10
+4.2− 8 Br [ηψψb1→+ J / J / ] = 2.4− .9 × 10 zz IfIf so,so, suchsuch aa rarerare decaydecay modemode perhapsperhaps willwill notnot bebe observedobserved inin thethe foreseeableforeseeable futurefuture inin experimentexperiment zz MoreMore recently,recently, thethe η b ÆÆJ/J/ψψ J/J/ψψ processprocess waswas calculatedcalculated atat thethe nextnext--toto--leadingleading orderorder accuracyaccuracy andand findfind thethe NLONLO correctioncorrection manymany enhanceenhance thethe branchingbranching fractionfraction toto thethe samesame levellevel ofof relativisticrelativistic correctioncorrection zz However,However, therethere existsexists aa disagreementdisagreement inin thisthis resultresult [Braguta & Kartvelishvili, arXiv:0907.2772] zz TheThe radiativeradiative correctioncorrection toto η b ÆÆJ/J/ψψ J/J/ψψ processprocess isis recalculatedrecalculated byby aa thirdthird party.party. PreliminaryPreliminary resultresult showsshows therethere isis nono agreementagreement withwith eithereither initialinitial calculationcalculation oror withwith thethe criticismcriticism zz Nevertheless,Nevertheless, numericalnumerical resultsresults areare allall inin aa similarsimilar orderorder [Sun, Hao, QCF, 2010] III. η c Exclusive Decays to Vector Meson Pair
zz Theoretically,Theoretically, thethe descriptiondescription ofof η c ÆÆVV VV processprocess isis aa longlong--standingstanding unsolvedunsolved problemproblem zzPerturbativelyPerturbatively,, thisthis processprocess isis helicityhelicity suppressedsuppressed zz ExperimentExperiment measurementmeasurement onon η c ÆÆVV VV processesprocesses
QWG7 Fermilab, 2010 CONG-FENG QIAO 31 zz ThereThere werewere lotslots ofof theoreticaltheoretical investigationsinvestigations onon thisthis issueissue inin thethe literature,literature, e.g.e.g. z In light-cone distribution formalism we calculate this process, up to the next-to-leading order in twist expansion, and find
z It in disagreement with the experiment measurements
[Sun, Hao, QCF, 2010] IV.IV. BriefBrief SummarySummary zz TheThe earlyearly runningrunning ofof thethe LHCLHC willwill supplysupply numerousnumerous eventevent numbersnumbers ofof J/J/ΨΨ pairpair productionproduction zz AtAt thethe LHC,LHC, wewe expectexpect thethe experimentexperiment measurementmeasurement onon doubledouble J/J/ΨΨ productionproduction maymay telltell usus moremore aboutabout thethe charmoniumcharmonium productionproduction mechanismmechanism
QWG7 Fermilab, 2010 CONG-FENG QIAO 34 z The η b ÆÆ J/J/ψψ J/J/ψψ process may still have problem in the NLO QCD calculation
z In the framework of quark model and perturbative QCD calculation, the η c ÆÆVV VV puzzle still exists
QWG7 Fermilab, 2010 CONG-FENG QIAO 35 ThankThank youyou forfor youryour attentionattention
QWG7 Fermilab, 2010 CONG-FENG QIAO 36