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The Relativistic Heavy Ion Frontier at the LHC

The Relativistic Heavy Ion Frontier at the LHC. Nobel Prize 2005. D. Gross. H.D. Politzer. F. Wilczek.

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The Relativistic Heavy Ion Frontier at the LHC

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  1. The Relativistic Heavy Ion Frontier at the LHC John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009

  2. Nobel Prize 2005 D. Gross H.D. Politzer F. Wilczek “Before [QCD] we could not go back further than 200,000 years after the Big Bang. Today…since QCD simplifies at high energy, we can extrapolate to very early times when nucleons melted…to form a quark-gluon plasma.” David Gross, Nobel Lecture (RMP 05) QCD Asymptotic Freedom (1973) The Strong Coupling Constant s heavy quark-antiquark coupling at finite T from lattice QCD O.Kaczmarek, hep-lat/0503017 Constituents - Hadrons, dressed quarks, quasi-hadrons, resonances? Coupling strength varies investigates (de-)confinement, hadronization, & intermediate objects. low Q2 high Q2 John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009

  3. e/T4 ~ # degrees of freedom few d.o.f.confined F. Karsch, et al. Nucl. Phys. B605 (2001) 579 many d.o.f.deconfined Behavior of QCD at High Temperature TC ~ 175  8 MeV  eC ~ 0.3 - 1 GeV/fm3 John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009

  4. Phase Diagram of QCD Matter Early universe see: Alford, Rajagopal, Reddy, Wilczek Phys. Rev. D64 (2001) 074017 LHC quark-gluon plasma RHIC Critical point ? Tc ~ 170 MeV Temperature color superconductor hadron gas nucleon gas nuclei CFL Neutron stars r0 vacuum net baryon density John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009

  5. The Quark-GluonPlasma – Present View from RHIC • Large e > ec (T > Tc) system – Sufficient for QGP formation – NOT hadrons • Particle ratios fit by thermal model T = 177 MeV ~ Tc (lattice QCD) • Large volume of quarks & gluons(hydrodynamics) –NOT just q & g scattering • Large elliptic & radial flow large pressure gradients • Ultra-low shear viscosity “nearly-perfect” fluid flow • Dynamics of quarks and gluons – QGP EoS,quark coalescence – NOT hadrons • Flow develops at quark level & depends upon constituent quark masses • Strongly-coupled quarks and gluons – NOT Weakly-interacting QGP (as thought) • Large parton energy loss John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009

  6. SPS RHIC LHC factor 28 5500 √sNN (GeV) 17 200 3.0 - 4.2 hotter T / Tc 1.1 1.9 15-60 denser e(GeV/fm3) 3 5 > 10 tQGP(fm/c) ≤ 2 2-4 longer-lived Simple Expectations – Heavy Ions at RHIC LHC RHICLHC RHIC and new Large Hadron Collider (LHC) at CERN in Geneva: Cover 3 decades of energy (sNN ~ 20 GeV – 5.5 TeV) To discover the properties of hot QCD (at T ~ 150 – 600 MeV) John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009

  7. Lead nucleus diameter ~ 14 fm g = 2,700 (Lorenz contracted) t ~ (14 fm/c) / g < 0.01 fm/c Geometry of Heavy Ion Collisions at LHC General Orientation Hadron masses ~ 1 GeV Hadron sizes ~ fm LHC Heavy Ion Collisions Ecm = 5.5 TeV per nn-pair Total Ecm = 1.54 PeV John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009

  8. Why Heavy Ions at the LHC? • Expect different timescales, shorter interaction times, higher energy (T) ! • Does system still equilibrate rapidly? • Thermal model still applies?  T still ~ Tc (lattice QCD)? • Does it flow? • Elliptic Flow change?  v2still saturated? More or less v2? • Is the QGP still strongly- (or weakly-) coupled? • Liquid? More like a gas?  No longer “nearly-perfect” fluid flow? •  Impact on energy loss!! • Understand parton energy loss!– What are the microscopic processes? •  mass and flavor dependence? •  use high pT jets & tag heavy quark jets • Understand response of the medium! • Strongly interacting quarks and gluons away-side response? •  use punch-through & associated jet • Color screening of the medium! • Deconfinement? (compare LQCD), initial T, other effects  J/y & Y states John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009

  9. LHC Heavy Ion Program LHC Heavy Ion Data-taking Pb + Pb at sNN = 5.5 TeV (1 month per year) • LHC Collider Detectors • ATLAS • CMS • ALICE John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009

  10. ATLAS Heavy Ion Program Overview: ATLAS has a broad heavy ion physics program - excels at jet and photon measurements Jets - reconstruct jets in a large kinematical range ET > 40 GeV and |η|<5 - perform key fragmentation measurements - jet shape and FF modifications - multi-jet studies Photons - isolate / measure photons in large range,ET > 10 GeV and |η|<2.5 - unique calorimeter design allows additional rejection beyond isolation US: Brookhaven National Lab Columbia University Iowa State University Stony Brook University John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009

  11. CMS Heavy Ion Program Overview: CMS has a broad heavy ion physics program - precision tracking< 2.5 - muon identification< 2.5 - high-res calorimetry< 5 - forward coverage CMS expects to excel at - photon-tagged jet measurements (FF modifications) - quarkonium measurements US: University of California at Davis University of Illinois at Chicago University of Iowa University of Kansas Los Alamos National Laboratory University of Maryland MIT University of Minnesota Rice University Vanderbilt University John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009

  12. CMS Heavy Ion Program John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009

  13. ALICE – Heavy Ion Experiment Overview: Soft Probes – “ala RHIC” • Expansion dynamics different from RHIC • Soft physics measurements ala RHIC + extended PID • Day 1 physics + Hard Probes – Jet Quenching • Jets, g , pi-zeros, leading particles to large pT Hard Probes – Heavy Quarks • Displaced vertices (Do K- p+) from TPC/ITS • Electrons in Transition Radiation Detector (TRD) Hard Probes – Quarkonia • J/y, , ’ (excellent),’’(2-3 yrs),y’ ??? US Members: Cal. St. U. – San Luis Obispo Creighton University University of Houston Lawrence Berkeley Nat. Lab Lawrence Livermore Nat. Lab Oak Ridge National Lab Ohio State University Purdue University University of Tennessee Wayne State University Yale University Affiliated members: Kent State University University of Texas – Austin John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009

  14. The ALICE Experiment John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009

  15. First LHC Beam in ALICE • ALICE ready for LHC collisions. • First LHC proton beams circulated on September 10th , 2008. • 450 GeV/c proton + pixel interaction John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009

  16. Heavy Ion Physics at the LHC – Day 1 LHC Heavy Ions – • expectations based on pQCD predictions & RHIC results • a lesson from RHIC – guided by theory + versatility + “expect the unexpected” Soft Physics (pT≤ 2 GeV/c) with heavy ions at LHC – • smooth extrapolation from SPS  RHIC LHC? LHC Particle Multiplicities John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009

  17. Elliptic Flow Heavy Ion Physics at the LHC – Day 2 LHC Heavy Ions – • expectations based on pQCD predictions & RHIC results • a lesson from RHIC – guided by theory + versatility + “expect the unexpected” Soft Physics (pT≤ 2 GeV/c) with heavy ions at LHC – • smooth extrapolation from SPS  RHIC LHC? • expansion dynamics different (initial state, flow, HBT, evolution of T, strange/charm/beauty) John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009

  18. leading particle hadrons hadrons leading particle Probing Hot QCD Matter with “Hard-Probes” • Initial Hard Parton Scattering • gluon-gluon • gluon-quark • quark-quark • Hard Probes • Large “pT” partons • Heavy quark – anti-quark • Initial Hard Parton Scattering • gluon-gluon • gluon-quark • quark-quark • Hard Probes • Large “pT” partons • Heavy quark – anti-quark  parton energy loss: modification of jets and leading particles & jet-correlations John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009

  19. Rate s sbb (LHC ) ~ 100 sbb (RHIC) scc (LHC) ~ 10 scc (RHIC) Hard Probes with LHC Heavy Ions • Significant increase in hard cross sections • (pT or mass > 2 GeV/c) at LHC –  slarge pT /stotal~ 2% at SPS • 50% at RHIC • 98% at LHC • “real” jets, large pT processes • abundance of heavy flavors • probe early times, calculable p0, s1/2= 5500 GeV p0, s1/2= 200 GeV p0, s1/2= 17 GeV John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009

  20. Hard Probes I – Jets and Parton Energy Loss John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009

  21. How does parton lose energy? e E q ~ m ^ q = m2 / L Parton Energy Loss Jet Quenching (Parton energy-loss, parton density, medium response) What happens to the radiation? Gluon radiation L Collision E-loss How does DE depend on type of parton? DEgluon > DEquark, m=0 > DEquark, m>0 • Jets, g , p0, leading particles to large pT • Modification of fragmentation • Medium response to E deposition - dissipation on near- and away-side John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009

  22. 200 GeV Au + Au central collision (STAR) Ejet = 21 GeV pT /cell (GeV/c) h f Au + Au experience (STAR) - HI Background Must suppress “soft” background: - small jet cones R = 0.3-0.4 - pT cut: pT > 1 – 2 GeV/c - EbyE out-of-cone background energy Jet-finding - Learning from Tevatron & RHIC p + p experience (CDF) - most of energy within cone of R =  (Dh2 + Df2) < 0.3 f h John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009

  23. Jet Quenching in CMS at the LHC f h Courtesy: CMS Jet spectra up to ET ~ 500 GeV (Pb-Pb, 0.5 nb-1, HLT(triggered) John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009

  24. Hard Probes II - Heavy Quark Production John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009

  25. Heavy Flavor RAA at RHIC & LHC! Heavy quark electrons at RHIC D & B mesons at LHC LHC RHIC Wicks & Gyulassy, Last Call for LHC Predictions RHIC: Large uncertainties - electrons only - ratio of c to b is uncertain - awaits upgraded vertex detectors LHC: measure D and B mesons - Precise measurements of RAA to large pT John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009

  26. Charm and Beauty E-Loss (e.g. ALICE) Heavy Quarks (mass/color dependence of parton energy-loss) Displaced vertices (Do K- p+) from tracking Electrons from Transition Radiation Detectors, EM Cal’s…. 1 nominal year: 107 central Pb-Pb events, 109 pp events errors: statistical (bars) and systematic (bands) Sensitive to color charge Sensitive to mass dep. E-loss calc.: Armesto, Dainese, Salgado, Wiedemann John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009

  27. Example – B-jet Physics in ALICE Quark vs gluon E-loss in medium B-jets - pure sample of quark jets John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009

  28. Quarkonia Heavy Quarks (mass/color dependence of parton energy-loss) • Displaced vertices (Do K- p+) from tracking • Electrons from Transition Radiation Detectors, EM Cal’s…. Quarkonia (initial temperature, Debye color screening, recombination) • J/y, , ’ (abundant),’’(fewer),y’ (more difficult) V(r) Confined Bound state (e.g. J/y) Deconfined r Quarkonium dissociation when rDebye ~ 1/(asT)< rqq Color screening of cc pair results in J/y (cc) suppression! John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009

  29. T/TC 1/r [fm-1] (1S) J/(1S) b’(2P) c(1P) ’’(3S) ’(2S) Quarkonia Heavy Quarks (mass/color dependence of parton energy-loss) • Displaced vertices (Do K- p+) from tracking • Electrons from Transition Radiation Detectors, EM Cal’s…. Quarkonia (initial temperature, Debye color screening, recombination) • J/y, , ’ (abundant),’’(fewer),y’ (more difficult) Karsch hep-lat/0502014v2 Measure melting order of cc: Y’, cc, J/y bb: U’’, U’, U John Harris (Yale) Tamura Symposium, U. T. – Austin, 20 – 22 Nov. 2008 John Harris (Yale U.) US LHC User’s Meeting, 24 October 2008

  30. Example – Quarkonia in CMS at the LHC f h Courtesy: CMS John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009

  31. The Quark-Gluon Plasma at RHIC & LHC –Today’s Perspective At LHC: Is the QCD phase diagram feature-less at 1 – 4 Tc? What happens as we go up in T (e.g. coupling)? Are there new phenomena? What’s the range of theoretical validity (non-pQCD, pQCD, strings)? Measure/understand parton energy loss at the fundamental level Establish flavor (gluon and quark mass) dependence Use jets and/or photons to establish hard-scattered parton energy Jet modifications - longitudinal & transverse “heating” Medium response to jet-heating (near- and away-side) Measure/use open charm and beauty decays (also as jet-tags) cc and bb states (Ti, screening/suppression, enhancement?) Developments in theory (lattice, hydro, parton E-loss, string theory…) “the next frontier!” John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009

  32. The End John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009

  33. ALICE Collaboration ~ 1000 Members (63% - CERN States) ~ 30 Countries ~ 100 Institutes~ 150 M CHF capital (+ ‘free’ magnet) John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009

  34. Hard Probe Capabilities of ALICE with EMCal EMCal improves detector capabilities: - Fast trigger ~10 -100 enhancement of jets - Improves jet reconstruction (plus TPC) - Goodg/p0discrimination increases coverage - Good electron/hadron discrimination • EMCal extends the physics of ALICE: • 104/year in minbias Pb+Pb: • inclusive jets: ET ~ 200 GeV • dijets: ET ~ 170 GeV • p0: pT ~ 75 GeV • inclusive g: pT ~ 45 GeV • inclusive e: pT ~ 30 GeV Thanks – Peter Jacobs John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009

  35. Example: High PT Suppression – RHIC and LHC f h Courtesy: B. Wyslouch and CMS John Harris (Yale) Tamura Symposium, U. T. – Austin, 20 – 22 Nov. 2008

  36. Tagging Jets with Photons for Parton Energy Search for & identifyprompt photon with largest pT Reconstruct the jet : Particles around leading particle inside a cone R = 0.3… Search for leading particle: fg - f leading~ 180º e.g. Eleading > 0.1 Eg John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009

  37. jet Charged particles for FF x: Rc=0.7 pT > 0 GeV/c Measuring the PbPb Fragmentation Function Jet energy determination: Rc=0.4 pT > 1 GeV/c f h J. Putschke, ECT 2008 More studies of background are needed & underway! John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009

  38. dN /dh = 2700 Top 0.5% σAA Example of Anticipated Jet Measurements Courtesy: ATLAS Reconstructed spectra not corrected for efficiency or energy resolution. John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009

  39. g - Jet Simulations in CMS at the LHC Quenched Pb+Pb Jet-finding efficiency False rate fraction (%) f h Select away-side jet with Df (g, jet) > 172o, |h|< 2 and ET (jet) > 30 GeV • ET (jet) cut reduces false rate to ~ 10% (Otherwise, no use of jet energy) • Jet finding efficiency increases sharply from 30 - 100 GeV jet ET Courtesy: C. Roland and CMS

  40. Unquenched Quenched Unquenched Quenched Fragmentation Functions in CMS ET, > 70GeV ET, > 100GeV Courtesy: C. Roland and CMS

  41. A Real Test of “Theories” in the Future from Heavy Flavors at RHIC & LHC? W. Horowitz, M. Gyulassy, arXiv:0804.4330v1 John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009

  42. A Test of “Theories” in the Future from Heavy Flavors at RHIC & LHC? W. Horowitz, M. Gyulassy, arXiv:0804.4330v1 John Harris (Yale) Tamura Symposium, U. T. – Austin, 20 – 22 Nov. 2008

  43. Wicks et al, nucl-th/0512076 Fragmentation Function of b-quark Measure B-jet Fragmentation Fctn - harder fragmentation of b-quark (higher <z> ) - Ejet measured more precisely - Better measurement of FF B-jet Physics WHDG, arXiv:nucl-th/0512076 Quark vs gluon E-loss in medium B-jets - pure sample of quark jets John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009

  44. Calorimeter Comparisons

  45. (charged particles) µ arm ALICE Detectors & Acceptance central barrel -0.9 < h < 0.9 • Df = 2p tracking, PID (TPC/ITS/ToF) • single arm RICH (HMPID) • single arm e.m. cal (PHOS) • jet calorimeter (proposed EMCal) forward muon arm 2.4 < h < 4 • absorber, 3 T-m dipole magnet10 tracking + 4 trigger chambers multiplicity detectors -5.4 < h < 3 • including photon counting in PMD trigger & timing detectors • 6 Zero Degree Calorimeters • T0: ring of quartz window PMT's • V0: ring of scint. Paddles John Harris (Yale) LNF Spring School, Frascati 12 – 16 May 2008

  46. ALICE Jet Trigger Yields in an LHC Pb + Pb Year Jet yield in 20 GeV bin Includes acceptance, efficiency, dead time, energy resolution Large gains due to jet trigger Large variation in statistical reach for different reference systems John Harris (Yale) Winter Workshop on Nuclear Dynamics, South Padre Is. TX – 4/8/08

  47. Quarkonia Performance dNch/dy = 4000 in central Pb-Pb

  48. Material Budget Cumulative mid-rapidity material budget for ALICE, ATLAS and CMS  ALICE Ideal Reconstruction and identification low pT : lowest material budget Hot Quarks 2008 - Estes Park B.Hippolyte

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