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High Energy Density Quantum Chromo-Dynamics Frontier at LHC-ALICE

High Energy Density Quantum Chromo-Dynamics Frontier at LHC-ALICE. Kenta Shigaki (Hiroshima University ) for the ALICE Collaboration GCOE Symposium “Emerging Frontiers of Physics” February 23, 2011 Kyoto University. Presentation Outline.

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High Energy Density Quantum Chromo-Dynamics Frontier at LHC-ALICE

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  1. High Energy DensityQuantum Chromo-Dynamics Frontierat LHC-ALICE Kenta Shigaki (Hiroshima University ) for theALICE Collaboration GCOE Symposium “Emerging Frontiers of Physics” February 23, 2011 Kyoto University

  2. Presentation Outline • experimental expeditions on QCD phase diagram • two exciting news • temperature well above the boundary at RHIC • newly started LHC/ALICE physics programs • ALICE first physics results from p+pand Pb+Pb • thermometer at ALICE • thermal photon strategies, feasibilities, prospects • summary and concluding remarks Emerging Frontiers of Physics – High Energy Density QCD Frontier at ALICE – K.Shigaki

  3. Goals of High Energy Nuclear Physics • why nucleus-nucleus at GeV/TeV range? • “system” of particles under strong QCD field • cf. “processes” between elementary particles • state of matter at ~ 10-5 seconds after Big Bang • cf. production/interaction of matter at ~ 10-12 seconds • hadronic mass generation via confinement • cf. particle mass generation via Higgs mechanism Emerging Frontiers of Physics – High Energy Density QCD Frontier at ALICE – K.Shigaki

  4. Expeditions on QCD Phase Diagram High Energy A+A Collisions • toward deconfined partonic phase • lattice Quantum Chromo-Dynamics predictions • critical temperature ~ 170 MeV • critical energy density ~ 1 GeV/fm3 Early Universe DeconfinedPartonic Phase (Quark-Gluon Plasma) Energy Density (Temperature) Tri-Critical Point Critical Temperature ~ 170 MeV Color Super-Conductivity Hadron Gas Color-Flavor Locking F. Karsch, Lect. Notes Phys. 583 (2002) 209 Neutron Star? Nucleus Baryon Density Emerging Frontiers of Physics – High Energy Density QCD Frontier at ALICE – K.Shigaki

  5. High Energy Nucleus Accelerators • from Bevalac/SIS/AGS/SPS to RHIC/LHC • from high density to high energy density regime • recent major facilities • BNL-AGS (11 A GeV 197Au + fixed target) • 28Si since 1986, 197Au since 1991; programs terminated • CERN-SPS (200 A GeV 208Pb + fixed target) • 32S since 1986, 208Pb since 1994; programs terminated • BNL-RHIC (100 + 100 A GeV 197Au + 197Au) • since 2000; in operation • CERN-LHC (2.8 + 2.8 A TeV 208Pb + 208Pb) • since 2009; in operation Emerging Frontiers of Physics – High Energy Density QCD Frontier at ALICE – K.Shigaki

  6. Two Exciting News from RHIC/LHC • temperature above Tc measured at RHIC • Phys.Rev.Lett. 104, 132301 (2010) • Phys.Rev.C 81, 034911 (2010) • new energy regime at ALICE/LHC • 900 GeV, 2.36 TeV, 7 TeV p+p in 2009–2010 • 2.76 TeV Pb+Pb in 2010 • higher statistics runs in 2011–2012 Emerging Frontiers of Physics – High Energy Density QCD Frontier at ALICE – K.Shigaki

  7. Relativistic Heavy Ion Collider at BNL • 2 independent super-conducting synchrotrons • up to 100 A GeV Au and/or 250 GeV (polarized) p • Au+Au/Cu+Cu/d+Au/p+p/… • 4 (2 presently) complimentary experiments Emerging Frontiers of Physics – High Energy Density QCD Frontier at ALICE – K.Shigaki

  8. RHIC Outcomes: New State of Matter • partonic: quarks’ degrees of freedom, screening • constituent quark number scaling of collective motion • J/Y suppression • dense: energy loss of (even heavy) quarks • jet quenching (high pT suppression) • jet modification • strongly coupled: perfect fluidity • hydro-dynamical collective motion • hot: thermally radiative • thermal (virtual) photons The matter is dense The matter is strongly coupled The matter may melt and/or regenerate J/y’s The matter modifies jets The matter is hot Emerging Frontiers of Physics – High Energy Density QCD Frontier at ALICE – K.Shigaki

  9. Photons as Thermometer • thermal radiation if in equilibrium • emission spectrum  temperature • real and virtual thermal photons Emerging Frontiers of Physics – High Energy Density QCD Frontier at ALICE – K.Shigaki

  10. Photon Production in HI Collisions Hadronization (Freeze-out) + Expansion Thermalization QGP phase? Mixed phase Pre-equilibrium Thermal Photon (QGP) Thermal Photon (HG) Jet-Photon Conversion Jet-Bremsstrahlung (QGP) Jet+Medium Compton/Annihillation Fragmentation Prompt Photon Thermal Photon Time Evolution Emerging Frontiers of Physics – High Energy Density QCD Frontier at ALICE – K.Shigaki

  11. Where to Catch Thermal Photons g q g q p p r g • high pT: pQCD photons • low pT: photons from hadronic gas • intermediate pT: QGP thermal photons dominant ! • also other sources • plus hadron decay photons everywhere hadron decay photons S.Turbideet al., PRC 69 014903 Emerging Frontiers of Physics – High Energy Density QCD Frontier at ALICE – K.Shigaki

  12. Naïve Way: Direct Real Photons • measured as “excess” above hadron decay photon • Au+Au result consistent with pQCD×binary scaling • challenging at lower pT due to smaller S/B ratio PRL 94, 232301 (2005) Emerging Frontiers of Physics – High Energy Density QCD Frontier at ALICE – K.Shigaki

  13. Alternative: “Almost Real” Photons • low mass electron-positron pairs • p+p: hadronic decay + pQCD photon at high pT • Au+Au: enhancement above ~ 135 MeV • no p0 decay virtual photon above p0 mass PHENIX (A. Adareet al.), PRL 104, 132301 (2010) Emerging Frontiers of Physics – High Energy Density QCD Frontier at ALICE – K.Shigaki

  14. Direct Photon Spectra via g and g* • real and virtual photon methods consisitent • p+p data consistent with pQCD down to low pT • Au+Au above scaled pQCD at low pT • excess ~ exponential with 221  19  19 MeV PHENIX (A. Adareet al.), PRL 104, 132301 (2010) NLO pQCD (W. Vogelsang) Emerging Frontiers of Physics – High Energy Density QCD Frontier at ALICE – K.Shigaki

  15. Initial Temperature Evaluation • initial temperature > data slope ~ 220 MeV • 300–600 MeV from models • hydro-dynamical models describing data within factor of 2 • w/ t0 = 0.15–0.6 fm/c • cf. phase transition predicted at ~ 170 MeV slope transition temperature PHENIX (A. Adareet al.), PRC 81, 034911 (2010) Emerging Frontiers of Physics – High Energy Density QCD Frontier at ALICE – K.Shigaki

  16. Across the Boundary and Beyond • phase boundary: Tc ~ 170 MeV, ec ~ 1 GeV/fm3 “free gas” ? “perfect fluid” Emerging Frontiers of Physics – High Energy Density QCD Frontier at ALICE – K.Shigaki

  17. ALarge Ion Collider Experiment • the heavy ion experiment at LHC • 33 countries; 116 institutes; > 1,000 members • as of November, 2010 CMS LHCb ALICE ATLAS, LHCf Emerging Frontiers of Physics – High Energy Density QCD Frontier at ALICE – K.Shigaki

  18. ALICE Control Room on 23.11.2009 ~ 16:35 Emerging Frontiers of Physics – High Energy Density QCD Frontier at ALICE – K.Shigaki

  19. The First Event ~ 16:41 Emerging Frontiers of Physics – High Energy Density QCD Frontier at ALICE – K.Shigaki

  20. Collisions! Collisions!! Collisions!!! ~ 16:42 events reconstructed in hours Emerging Frontiers of Physics – High Energy Density QCD Frontier at ALICE – K.Shigaki

  21. First LHC Physics Paper, 28.11.2009 • charged particle density measurement • dNch/dh in p+p at 900 GeV • 3.10  0.13  0.22 (inel.) • 3.51  0.15  0.25 (NSD) ALICE Collaboration Eur.Phys.J.C65:111-125, 2010 National Geographic News (04.12.2009) ‘….a machine called ALICE.... found that a (!) proton-proton collision recorded on November 23 created the precise ratio of matter and antimatter particles predicted from theory..’ Emerging Frontiers of Physics – High Energy Density QCD Frontier at ALICE – K.Shigaki

  22. 7 TeV; The Highest Ever! • ALICE 2010 p+p data taking • > 800 M interactions • > 100 M muon triggers for J/Y • > 25 M high multiplicity triggers Emerging Frontiers of Physics – High Energy Density QCD Frontier at ALICE – K.Shigaki

  23. High Precision Measurements • wide pT coverage with particle identification • unique low pT reach at LHC Emerging Frontiers of Physics – High Energy Density QCD Frontier at ALICE – K.Shigaki

  24. Almost Zero Baryo-Chemical Potential • anti-proton/proton ratio in mid-rapidity region • 0.957  0.006 (stat)  0.014 (sys) at 900 GeV • 0.990  0.006 (stat)  0.014 (sys) at 7 TeV ALICE (K. Aamodtet al.), PRL 105, 072002 (2010) Emerging Frontiers of Physics – High Energy Density QCD Frontier at ALICE – K.Shigaki

  25. Vital Reference in New Energy Domain • e.g. closed/open heavy flavors • J/Y (c + c), D0, D, D (c + u/d (/s), u/d (/s) + c) J/Y m+m- J/Y e+e- Emerging Frontiers of Physics – High Energy Density QCD Frontier at ALICE – K.Shigaki

  26. Now, Long Awaited Pb+Pb Run • 2.76 TeV Pb+Pb from 07.11.2010–06.12.2010 • 14 times higher sNN than at RHIC Emerging Frontiers of Physics – High Energy Density QCD Frontier at ALICE – K.Shigaki

  27. ALICE 2010 Pb+Pb Data Taking • ~ 10 mb-1 delivered; > 90 M recorded in total • ~ 3 ×initial expectation Emerging Frontiers of Physics – High Energy Density QCD Frontier at ALICE – K.Shigaki

  28. Collision “Centrality” • tight correlation among several measures • scaling to “# participants” + “# binary collisions” • based on geometrical Glauber model • most peripheral collisions not separable from EM processes Emerging Frontiers of Physics – High Energy Density QCD Frontier at ALICE – K.Shigaki

  29. Multiplicity and Energy Density • dNch/dh = 1600  76 (sys) • high side of predictions • faster growth with s than in p+p • i.e. s dependent nuclear amplification • ~ 3 times higher energy density than at RHIC • lower limit; likely higher with shorter time scale ALICE (K. Aamodtet al.), PRL 105, 252301 (2010) back at RHIC Emerging Frontiers of Physics – High Energy Density QCD Frontier at ALICE – K.Shigaki

  30. Hotter, Bigger, Longer-Lived Fireball Enhancement p+p 7 TeV radius ~ 1/width Pb+Pb 2.76 TeV Pair Momentum Difference • particle interferometry • aka HBT or Bose Einstein correlations • quantum enhancement of identical bosons close in phase space • space-time evolution of co-moving volume • lifetime also accessible via Fourier transformation (E, p)  (t, x) • ~ 2 times bigger, 20–30% long-lived than at RHIC • ~ 300 fm3, ~ 10 fm/c ALICE (K. Aamodtet al.), PLB 696, 328 (2010) Emerging Frontiers of Physics – High Energy Density QCD Frontier at ALICE – K.Shigaki

  31. Jet Quenching and Mono-Jet Df Dh Dh Df • quark/gluon energy loss in partonic matter • first signature of hot and dense matter at RHIC • jet energy imbalance in single events • new at LHC! • full statistics analysis in progress • ALICE uniquely capable to include low pT particles high pT hadron quenched jet hadrons (jet) quark (anti-)quark hadrons (jet) high pT hadron Emerging Frontiers of Physics – High Energy Density QCD Frontier at ALICE – K.Shigaki

  32. Jet Quenching in Traditional View normalization including CDF data normalization by 0.9 TeV ×NLO (2.76 TeV) / NLO (0.9 TeV) • particle yields suppressed at high pT • quantified with “nuclear modification factor” • similar overall trend at LHC and RHIC • minimum value ~1.5 times smaller • rising with pT; newly clear at LHC • p+p reference limiting; 2.76 TeV p+p needed ALICE (K. Aamodtet al.), PLB 696, 30 (2011) LHC-ALICE charged particles RHIC-PHENIX p0 Emerging Frontiers of Physics – High Energy Density QCD Frontier at ALICE – K.Shigaki

  33. Heavy/Hard Probes at QCD Machine • ~ 10×charming and ~ 100×beautiful than at RHIC • powerful probes with known mass and color charge charm/beauty sNN (mb) shadowing multiplicity • p+p 14 TeV 11.2/0.5 1.0/1.0 0.16/0.007 • central Pb+Pb 6.6/0.2 0.65/0.85 115/4.6 • jets also even more powerful than at RHIC Emerging Frontiers of Physics – High Energy Density QCD Frontier at ALICE – K.Shigaki

  34. Closed Heavy Flavors in Pb+Pb • J/Y suppression as a signature of deconfinement • observed at RHIC and SPS; interpretation ambiguous • sequential melting?  further suppression at LHC • melting and regeneration competing?  enhancement at LHC •  another key to resolve mechanism • (partial) answer expected from 2010 data • ~ a few 103 J/Y in hand Emerging Frontiers of Physics – High Energy Density QCD Frontier at ALICE – K.Shigaki

  35. More Fun Stuffs, Too • e.g. anti-nuclei • … and even more exotics, e.g. anti-hyper-nuclei ~ 2 M minimum-bias Pb+Pb Emerging Frontiers of Physics – High Energy Density QCD Frontier at ALICE – K.Shigaki

  36. LHCRun History and Plan • LHC run history and schedule • 09.2008 first beam circulation • 11–12.2009p+p, s = 900 GeV, 2.36 TeV • 2010–2012 p+p at s = 7 TeV (and 2.76 TeV) Pb+Pb at sNN = 2.76 TeV • expectations in following few years • p+ps = 14 TeV, 1031 cm-2s-1 (ALICE), 107 s/y s = 5.5 TeV, 1031 cm-2s-1, 106 s/y×1 y • Pb+PbsNN = 5.5 TeV, 1027 cm-2s-1, 106 s/y • p+Pb sNN = 8.8 TeV, 1029 cm-2s-1, 106 s/y×1 y • Ar+Ar sNN = 6.3 TeV, 1029 cm-2s-1, 106 s/y×1 y Emerging Frontiers of Physics – High Energy Density QCD Frontier at ALICE – K.Shigaki

  37. Thermal Photon Hunting at ALICE • ALICE photon spectrometer: PHOS • photons,nuetral mesons, jet tagging • + L0, L1 trigger capability • wide coverage from 100 MeV to 100 GeV • high eneregy resolution, high granularity • s/E ~ 3 %/E up to 100 GeV • PbWO4 crystals of 22 (1.0 RMoliere)×22×180 (20 X0) mm3 • APD+ charge sensitive pre-amplifier readout • cooled and controlled at -250.1 C • |h| < 0.12, Df = 100 at 4.6 m • 56×64×5 modules; 17,920 channels, 12.5 t • 3 (/5) modules in operation hadron decays pQCD processes ~ pT-n compton scattering annihilation fragmentation thermal ~ e-E/T jet-medium interaction jet-photon conversion bremsstrahlung Emerging Frontiers of Physics – High Energy Density QCD Frontier at ALICE – K.Shigaki

  38. Early Physics Prospects via Photons • (very) high pT neutral meson suppression • high acceptance/statistics in early p+p and Pb+Pb • comparable to (or better than) years at RHIC • higher pT reach + stronger suppression at LHC • clearer measurement of quark energy loss • (less background for direct photon measurement) Emerging Frontiers of Physics – High Energy Density QCD Frontier at ALICE – K.Shigaki

  39. Toward Thermometer at LHC • prospect of thermal photon direct measurement • hotter, bigger, longer-lived fireball • reduced background due to quenching • ALICE-PHOSdetector • signal/background ~ 4–10 % (3 GeV/c) – 25–50 % (10 GeV/c) • systematic error ~ 8.9 % (2 GeV/c) – 5.7 % (10 GeV/c) • access to thermal properties of partonic system • Quark-Gluon Plasma factory • frontier expeditions on QCD phase diagram Emerging Frontiers of Physics – High Energy Density QCD Frontier at ALICE – K.Shigaki

  40. Summary and Concluding Remarks • boundary to partonic phase crossed at RHIC! • Tinit = 300–600 MeV “measured” • transition predicted at ~ 170 MeV by lattice QCD • LHC/ALICE now exploring new QCD frontier regime • 900 GeV, 2.36 TeV, 7 TeV p+p in 2009–2010 • 2.76 TeV Pb+Pb in 2010 • higher statistics p+p and Pb+Pb in 2011–2012 • expeditions hunting partonic phase properties • hard/heavy probes at “QCD machine” • “soft” photonic probes for comprehensive understanding • physics harvests blooming at LHC HI programs Emerging Frontiers of Physics – High Energy Density QCD Frontier at ALICE – K.Shigaki

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