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J/ ψ Production in A+A Collisions At STAR

J/ ψ Production in A+A Collisions At STAR. Ota Kukral for the STAR Collaboration Czech Technical University in Prague. RHIC & AGS Annual Users ’ Meeting 17 June 2014. Outline. J/ ψ reconstruction Au+Au results J/ ψ in U+U Future prospects : MTD and HFT

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J/ ψ Production in A+A Collisions At STAR

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  1. J/ψ Production in A+A CollisionsAt STAR Ota Kukral forthe STAR Collaboration CzechTechnical University in Prague RHIC & AGS Annual Users’ Meeting 17 June 2014

  2. Outline • J/ψreconstruction • Au+Au results • J/ψ in U+U • Future prospects: MTD and HFT • Summaryandoutlook Ota Kukral RHIC AGS Annual Users' Meeting 2014

  3. Electron ID • J/ψ → e+e- (B.R. 5.9%) • TPC: • nσ – distance fromtheexpectedmeanvalueofdE/dxexpressed as numberof standard deviations • Often-1.5 < nσelectron < 2.0 TPC only |1/β - 1| < 0.03 Ota Kukral RHIC AGS Annual Users' Meeting 2014

  4. Electron ID • J/ψ → e+e- (B.R. 5.9%) • TPC: • nσ – distance fromtheexpectedmeanvalueofdE/dxexpressed as numberof standard deviations • Often-1.5 < nσelectron < 2.0 • TOF: • Usedmainlyforp < ~1.4GeV/c • 0.97 < 1/β < 1.03 (as βelectron ≈ 1) TPC only |1/β - 1| < 0.03 TPC + TOF Ota Kukral RHIC AGS Annual Users' Meeting 2014

  5. Electron ID • J/ψ → e+e- (B.R. 5.9%) • TPC: • nσ – distance fromtheexpectedmeanvalueofdE/dxexpressed as numberof standard deviations • Often-1.5 < nσelectron < 2.0 • TOF: • Usedmainlyforp < ~1.4GeV/c • 0.97 < 1/β < 1.03 (as βelectron ≈ 1) • BEMC: • Usedforp > ~ 1.4GeV/c • Electrons deposit most oftheirenergy:E/p shouldbearound 1 TPC only |1/β - 1| < 0.03 TPC + TOF Ota Kukral RHIC AGS Annual Users' Meeting 2014

  6. J/ψ → e+e-signals • Combinatorial background estimated by like-sign and mixed events techniques • Clear signals for both low and high pTAu+Au collisions STARlow-pT :arXiv:1310.3563 high-pT: Phys.Lett. B722, 55(2013) Ota Kukral RHIC AGS Annual Users' Meeting 2014

  7. J/ψspectra in Au+Au at 200 GeV • Large pT range • Covers 0-10 GeV/c • J/ψ spectra softer at low pT than the TsallisBlast-Wave model prediction with the same freeze-out parameters as for light hadrons • Recombination at low pT? • Small radial flow? STARlow-pT :arXiv:1310.3563 high-pT: Phys.Lett. B722, 55(2013) Tsallis Blast-Wave model: Z.Tang et al., Chin.Phys.Lett. 30, 031201(2013) Ota Kukral RHIC AGS Annual Users' Meeting 2014

  8. J/ψspectra in Au+Au at 200 GeV • Viscous hydrodynamics • J/ψ decoupling temperature of 120 and 165 MeV fails to describe thelowpT data • Y. Liu et al. • model includesJ/y suppression due to color screening and the statistical regeneration • describes the data well • peripheral: initial production dominates. central: regeneration becoming more significant at low pT. Y. Liu et al., Phys. Lett. B 678,72 (2009) U. W. Heinz and C. Shen (2011), privatecommunication. Ota Kukral RHIC AGS Annual Users' Meeting 2014

  9. J/ψcoldnuclearmattereffects • Nuclearmodificationfactor • RdAu ≈ 1 forhighpT • Coldnucleareffects are smallathighpT • HighpTresults in A+A collisionsprovide a cleanerprobeofthe J/ψinteractionwiththehotnuclearmatter PHENIX STAR Preliminary PHENIX data: Phys. Rev. C 87, 034904 (2013) Model: E.Eskola, H.PaukkuneneaandC.Salgo, Nucl. Phys. A 830, 599 (2009) Ota Kukral RHIC AGS Annual Users' Meeting 2014

  10. J/ψ suppression in Au+Au at 200 GeV • Nuclear modification factor • Increase from low pT to high pT • Consistent with unity at high pT peripheral collisions • More suppression in central than in peripheral collisions even at high pT STARlow-pT : arXiv:1310.3563 high-pT: Phys.Lett. B722, 55(2013) Liu et al., PLB 678, 72 (2009) Zhao and Rapp, PRC 82,064905(2010) PLB 664, 253 (2008) Ota Kukral RHIC AGS Annual Users' Meeting 2014

  11. J/ψsuppression in Au+Au at 200 GeV • Systemsize (Npart) dependence • RAAdecreaseswiththesizeofthesystem • Modelsincludinginitialproductionandrecombinationreasonablydescribethe J/ψ in ourmeasuredpT region • J/ψ in central collisions suppressed even at high pT • HighpT data lesssuppressedthanlowpT STARlow-pT : arXiv:1310.3563 high-pT: Phys.Lett. B722, 55(2013) Liu et al., PLB 678, 72 (2009) Zhao and Rapp, PRC 82,064905(2010) PLB 664, 253 (2008) PHENIX Phys. Rev. Lett. 98, 232301 (2007) Ota Kukral RHIC AGS Annual Users' Meeting 2014

  12. J/ψsuppression in Au+Au at 200 GeV • System size (Npart) dependence • RAA decreases with the size of the system • Models including initial production and recombination reasonably describe the J/ψ in our measured pT region • J/ψ in central collisions suppressed even at high pT • High pT data less suppressed thanlowpT • HighpTJ/ψat LHC (prompt) is more suppressedthanat RHIC (inclusive) STAR: Phys.Lett. B722, 55(2013) CMS: JHEP 05 (2012) 063

  13. J/ψatBeamEnergyScan (BES) • Similar suppression at RHIC and SPS • RHIC BES program: unique tool to study theinterplayof CNM, screeningandregenerationeffects • Quarkoniasequentialmelting: thermometerof QGP STARlow-pT : arXiv:1310.3563 high-pT: Phys.Lett. B722, 55(2013) SPS: Scomparin, QM2006 Ota Kukral RHIC AGS Annual Users' Meeting 2014

  14. J/ψatBeamEnergyScan (BES) • J/ψobservedat 200, 62.4 and 39 GeV • Data from Run 10 • Signalup to pT 4 GeV/c for 39 and 62.4 GeV 39 GeV 62.4 GeV 200 GeV Ota Kukral RHIC AGS Annual Users' Meeting 2014

  15. J/ψsuppressionat RHIC BES • RAA for J/ψ in Au+Au at 200, 62.4 and 39 GeV • Similar suppression for measured energies • pp reference isbased on CEM calculations • Large theoretical uncertainty • Consistent with theoretical calculations STAR Preliminary p+p references for39 and 62 GeV: Nelson, Vogt et al., PRC87, 014908 (2013) Theoretical curves: Zhao, RappPRC82, 064905 (2010) Ota Kukral RHIC AGS Annual Users' Meeting 2014

  16. J/ψsuppressionat RHIC BES • Central vs. peripheral collisions: • Significant suppression at 62.4 GeV, similar to 200 GeV STAR Preliminary Ota Kukral RHIC AGS Annual Users' Meeting 2014

  17. J/ψellipticflow v2 • Consistentwithzero(pT > 2 GeV/c) • Theonly hadron so far thatdoes not flow. • DisfavorscoalescencefromthermalizedcharmquarksathighpT Phys. Rev. Lett. 111 (2013) 52301 [29] L. Yan, P. Zhuang, N. Xu, PRL 97 (2006), 232301. [30] V. Greco, C.M. Ko, R. Rapp, PLB 595, 202. [32] X. Zhao, R. Rapp, arXiv:0806.1239 (2008) [33] Y. Liu, N. Xu, P. Zhuang, Nucl. Phy. A, 834, 317. [34] U. Heinz, C. Shen, private communication. Ota Kukral RHIC AGS Annual Users' Meeting 2014

  18. Motivationfor U+U collisions • U+U collisions at 193 GeV per nucleonpair (2012) • Uranium nucleus is larger than Auand non-spherical • U+U collisions (orientationaveraged) providehigherenergydensity • Tip-to-tip collisionsprovidethehighestenergydensity STAR Collaboration: arXiv 1310.3563 (2013) Tip-to-tip collision Ota Kukral RHIC AGS Annual Users' Meeting 2014

  19. Motivationfor U+U collisions • U+U collisions at 193 GeV per nucleonpair (2012) • Uranium nucleus is larger than Auand non-spherical • U+U collisions (orientationaveraged) providehigherenergydensity • Tip-to-tip collisionsprovidethehighestenergydensity STAR Collaboration: arXiv 1310.3563 (2013) Tip-to-tip collision Ota Kukral RHIC AGS Annual Users' Meeting 2014

  20. Motivationfor U+U collisions • U+U collisions at 193 GeV per nucleonpair (2012) • Uranium nucleus is larger than Auand non-spherical • U+U collisions (orientationaveraged) providehigherenergydensity • Tip-to-tip collisionsprovidethehighestenergydensity Tip-to-tip collision Ota Kukral RHIC AGS Annual Users' Meeting 2014

  21. J/ψ invariant yieldand RAA in U+U • Nuclear modification factor as a function of pTsimilar to Au+Au • Study of centrality dependence of RAAongoing • centraltrigger data available p+p reference from 200 GeVused Ota Kukral RHIC AGS Annual Users' Meeting 2014

  22. J/ MuonTelescopeDetector (MTD) • J/ψ → μ+μ-(B.R. 5.9%) • No γconversion, lesscontributionfromDalitzdecays • Triggercapabilityfor J/ψ in central A+A collisions • Full MTD installedforyear 2014 MTD (MRPC) Ota Kukral RHIC AGS Annual Users' Meeting 2014

  23. HeavyFlavorTracker (HFT) • Inner tracking system - precise pointing resolution • Study of non-prompt J/ψ (B → J/ψ + X; cτ≈ 500 μm) • Installedforyear 2014 Simulationofseparationof prompt and non-prompt J/ψusing HFT Ota Kukral RHIC AGS Annual Users' Meeting 2014

  24. Summaryandoutlook • J/ψ in Au+Au at 200 GeV • Suppression observed – increases with centrality and decreases with pT • Elipticflowconsistentwithzero (pT>2 GeV/c) • J/ψ in Au+Au at 39 GeV and 62.4GeV • Similar suppression as in 200 GeV within uncertainties • J/ψ in U+U collisions at 193 GeV • Suppresionpatternsimilar to Au+Au • Outlook • 2014: Largestatistics Au+Au at 200 GeV • MuonTelescopeDetector: J/ψ → μ+μ- • Heavy Flavor Tracker: separation of prompt and non-prompt J/ψ Ota Kukral RHIC AGS Annual Users' Meeting 2014

  25. Additional slides Ota Kukral RHIC AGS Annual Users' Meeting 2014

  26. Motivation • Mass of charm quark is high (~1.3 GeV/c2) • Production can be described by pQCD • Produced early in hard processes • Quarkonia (J/ψ, ϒ) are expected to be suppressed in QGP • In-medium screening of color charge – temperaturedependent • Otherimportanteffects: • Recombinationfromuncorrelatedcharmpairs • Observedyields are a mixtureofdirectproduction + feeddown (alsofrom B meson) • Coldnucleareffects (such as modification to PDFsornuclearabsorption) Satz, Nucl. Phys. A783:249-260(2007) Ota Kukral RHIC AGS Annual Users' Meeting 2014

  27. STAR experiment • BrookhavenNationalLaboratory, USA • TimeProjectionChamber (TPC) • Particlemomentum, dE/dx • TimeOfFlight (TOF) • Particlevelocity (1/β) • BarrelElectromagneticCalorimeter (BEMC) • Electron/photonenergy Ota Kukral RHIC AGS Annual Users' Meeting 2014

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