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High T and r QCD in the QCD Lab Era

High T and r QCD in the QCD Lab Era. The QCD laboratory era Overview Fundamental questions Opportunities with heavy ion collisions Key experimental probes and their status Hard probes Electromagnetic radiation Roadmap towards the QCD Lab era Burning open questions as of today

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High T and r QCD in the QCD Lab Era

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  1. High T and r QCD in the QCD Lab Era • The QCD laboratory era • Overview • Fundamental questions • Opportunities with heavy ion collisions • Key experimental probes and their status • Hard probes • Electromagnetic radiation • Roadmap towards the QCD Lab era • Burning open questions as of today • Detector and accelerator upgrades • Well into the QCD lab and the LHC era • Jet tomography • Quarkonium • Low energy program • RHIC beyond PHENIX and STAR upgrades

  2. Fundamental Questions in QCD 2007 2012 QCD Laboratory at BNL Axel Drees

  3. Long Term Timeline of Heavy Ion Facilities 2009 2012 2015 2006 QCD Laboratory at BNL RHIC PHENIX & STAR upgrades electron cooling “RHIC II” electron injector/ring “e RHIC” LHC RHIC II and STAR/PHENIX upgrades will flourish in QCD Lab era! FAIR Phase III: Heavy ion physics Axel Drees

  4. Quark Matter: Many new phases of matter Asymptotically free quarks & gluons Strongly coupled plasma Superconductors, CFL …. Experimental access to “high” T and moderate r region: heavy ion collisions Pioneered at SPS and AGS Ongoing program at RHIC Study high T and r QCD in the Laboratory Exploring the Phase Diagram of QCD T Quark Matter Mostly uncharted territory sQGP TC~170 MeV Hadron Resonance Gas Overwhelming evidence: Strongly coupled quark matter produced at RHIC temperature Nuclear Matter baryon chemical potential 1200-1700 MeV 940 MeV mB Axel Drees

  5. V2 PHENIX Huovinen et al Pt GeV/c Quark Matter Produced at RHIC III. Jet Quenching I. Transverse Energy Bjorken estimate: t0~ 0.3 fm PHENIX 130 GeV dNg/dy ~ 1100 central 2%  ~ 10-20 GeV/fm3 II. Hydrodynamics Initial conditions: therm ~ 0.6 -1.0 fm/c ~15-25 GeV/fm3 Heavy ion collisions provide the laboratory to study high T QCD! Axel Drees

  6. T Quark Matter TC~170 MeV SIS Hadron Resonance Gas temperature Nuclear Matter baryon chemical potential 1200-1700 MeV 940 MeV mB Fundamental Questions which may find experimental answers using heavy ion collisions! • Exploring the QCD phase diagram: • What is the nature of a relativistic quantum fluid? • What are the relevant degrees of freedom? • Is there a critical point? • Is there asymptotically free quark matter? • Physics at the phase transition: • Why are quarks confined in hadrons? • Why are hadrons massive and what is the relation to chiral symmetry breaking? Axel Drees

  7. Fundamental Questions (II) Related to time evolution of the collision! • Initial state and entropy generation: • What is the low x cold nuclear matter phase? • How and why does matter thermalize so fast? Axel Drees

  8. LHC/CERN T Quark Matter RHIC/BNL FAIR/GSI TC~170 MeV thermal freeze out chemical freeze out SIS Hadron Resonance Gas temperature Nuclear Matter baryon chemical potential 1200-1700 MeV 940 MeV mB Heavy Ion Collisions Provide the Laboratory Different accelerators probe different regions of the phase diagram! • Exploring the QCD phase diagram: • Is there asymptotically free quark matter? • What is the nature of a relativistic quantum fluid? What are the relevant degrees of freedom? • Is there a critical point? • Physics at the phase transition: • Why are quarks confined in hadrons? • Why are hadrons massive and what is the relation to chiral symmetry breaking? Axel Drees

  9. Heavy Ion Collisions Provide the Laboratory Related to time evolution of the collision! • Initial state and entropy generation: • How and why does matter thermalize so fast? • What is the low x cold nuclear matter phase? eRHIC RHIC LHC FAIR Axel Drees

  10. Comparison of Heavy Ion Facilities Initial conditions • FAIR: cold but dense baryon rich matter • fixed target p to U • sNN ~ 1-8 GeV U+U • Intensity ~ 2 109/s  ~10 MHz • ~ 20 weeks/year • RHIC: dense quark matter to hot quark matter • Collider p+p, d+A and A+A • sNN ~ 5 – 200 GeV U+U • Luminosity ~ 8 1027 /cm2s  ~50 kHz • ~ 15 weeks/year • LHC: hot quark matter • Collider p+p and A+A • Energy ~ 5500 GeV Pb+Pb • Luminosity ~ 1027 /cm2s  ~5 kHz • ~ 4 week/year FAIR  TC LHC 3-4 TC RHIC  2 TC RHIC is unique and at “sweet spot” Complementary programs with large overlap: High T: LHC  adds new high energy probes  test prediction based on RHIC data High r: FAIR  adds probes with ultra low cross section Axel Drees

  11. Key Experimental Probes of Quark Matter • Rutherford experiment a atom discovery of nucleus SLAC electron scattering e  proton discovery of quarks QGP penetrating beam (jets or heavy particles) absorption or scattering pattern Nature provides penetrating beams or “hard probes” and the QGP in A-A collisions • Penetrating beams created by parton scattering before QGP is formed • High transverse momentum particles  jets • Heavy particles  open and hidden charm or bottom • Calibrated probes calculable in pQCD • Probe QGP created in A-A collisions as transient state after ~ 1 fm Axel Drees

  12. jet jet Central Au-Au PHENIX preliminary Hard Probes: Light quark/gluon jets • Status • Calibrated probe • Strong medium effect • Jet quenching • Reaction of medium to probe (Mach cones, recombination, etc. ) • Matter is very opaque • Significant surface bias • Limited sensitivity to energy loss mechanism hydro vacuum fragmentation reaction of medium Axel Drees

  13. N. Armesto et al, nucl-ex/0511257 STAR Preliminary Hard Probes: Open Heavy Flavor • Status • Calibrated probe? • Charm follows binary scaling • pQCD under predicts cross section by factor 2-5 • Strong medium effects • Significant charm suppression • Significant charm v2 • Little room for bottom production • Limited agreement with energy loss calculations Axel Drees

  14. Hard Probes: Quarkonium • Status • J/y production is suppressed • Similar at RHIC and SPS • Consistent with consecutive melting of c and y’ • Consistent with melting J/y followed by regeneration • Recent Lattice QCD developments • Quarkonium states do not melt at TC Karsch, Kharzeev, Satz, hep-ph/0512239 Axel Drees

  15. e- g* g e+ e- p r* g g* e+ p g q e- q g q p p q e+ r g Key Experimental Probes of Quark Matter (II) real or virtual photons (lepton pairs) hadron gas: photons low mass lepton pairs QGP: photons medium mass • Electromagnetic radiation: • No strong final state interaction • Carry information from time of emission to detectors • Thermal photons and dileptons sensitive to highest temperature of plasma • Dileptons sensitive to medium modifications of meson in mixed/hardon phase • (only known potential handle on chiral symmetry restoration!) Axel Drees

  16. Electromagnetic Radiation • Status • First indication of thermal radiation at RHIC • Strong modification of meson properties • Precision data from NA60 • Emerging data from RHIC • Theoretical link to chiral symmetry restoration remains unclear NA60 Axel Drees

  17. “Burning” Open Issues: • Jets and heavy quarks • Which observables are sensitive to details of energy loss mechanism? • How important is collisional energy loss? • Do we understand relation between energy loss and energy density? • Where are the B-mesons? • Which probes are sensitive to the medium and what do they tell us? • Quarkonium • Is the J/y screened or not? • Can we really extract screening length from data? • Electromagnetic radiation • Can we measure the initial temperature? • Is there a quantitative link from dileptons to chiral symmetry resoration? Answers will come from QCD laboratory and LHC Axel Drees

  18. Midterm Strategy for RHIC Facility Key measurements require upgrades of detectors and/or RHIC luminosity • Detectors: • Particle identification  reaction of medium to eloss, recombination • Displaced vertex detection  open charm and bottom • Increased rate and acceptance  Jet tomography, quarkonium, heavy flavors • Dalitz rejection  e+e- pair continuum • Forward detectors  low x, CGC • Accelerator: • EBIS  Systems up to U+U • Electron cooling  increased luminosity Axel Drees

  19. PHENIX Detector Upgrades at a Glance • Central arms: • Electron and Photon measurements • Electromagnetic calorimeter • Precision momentum determination • Hadron identification • Muon arms: • Muon • Identification • Momentum determination • Dalitz/conversion rejection(HBD) • Precision vertex tracking (VTX) PID (k,p,p) to 10 GeV (Aerogel/TOF) • High rate trigger (m trigger) • Precision vertex tracking (FVTX) • Electron and photon measurements • Muon arm acceptance (NCC) • Very forward (MPC) Axel Drees

  20. NCC NCC HBD MPC MPC VTX & FVTX Future PHENIX Acceptance for Hard Probes EMCAL 0 f coverage 2p EMCAL -3 -2 -1 0 1 2 3 rapidity (i) p0 and direct g with combination of all electromagnetic calorimeters (ii) heavy flavor with precision vertex tracking with silicon detectors combine (i)&(ii) for jet tomography with g-jet (iii) low mass dilepton measurments with HBD + PHENIX central arms Axel Drees

  21. Full Barrel Time-of-Flight system Forward Meson Spectrometer Forward triple-GEM EEMC tracker STAR Upgrades DAQ and TPC-FEE upgrade Integrated Tracking Upgrade Forward silicon tracker HFT pixel detector Barrel silicon tracker Axel Drees

  22. RHIC Upgrades Overview X upgrade critical for success O upgrade significantly enhancements program Axel Drees

  23. Which Measurements are Unique at RHIC? • General comparison to LHC • LHC and RHIC (and FAIR) are complementary • They address different regimes (CGC vs sQGP vs hadronic matter) • Experimental issues: “Signals” at RHIC overwhelmed by “backgrounds” at LHC • Measurement specific (compared to LHC) • Charm measurements: favorable at RHIC • Charm is a “light quark” at LHC, no longer a penetrating probe • Abundant thermal production of charm • Large contribution from jet fragmentation and bottom decay • Bottom may assume role of charm at LHC • Quarkonium spectroscopy: J/, ’ , c easier to interpreter at RHIC • Large background from bottom decays and thermal production at LHC • Upsilon spectroscopy can only be done at LHC • Low mass dileptons: challenging at LHC • Huge irreducible background from charm production at LHC • Jet tomography: measurements and capabilities complementary • RHIC: large calorimeter and tracking coverage with PID in few GeV range • Extended pT range at LHC Axel Drees

  24. Quarkonium and Open Heavy Flavor * large background ** states maybe not resolved *** min. bias trigger **** pt > 3 GeV Will be statistics limited at RHIC and LHC! Compiled by T.Frawley Potential improvements with dedicated experiment 4p acceptance J/Y, Y’ 10x  2-10x background rejection cc ???? Note: for B, D increase by factor 10 extends pT by ~3-4 GeV • LHC relative to RHIC • Luminosity ~ 10% • Running time ~ 25% • Cross section ~ 10-50x • ~ similar yields! There is room for improvement if needed! Axel Drees

  25. Comments on High pT Capabilities • LHC • Orders of magnitude larger cross sections • ~3 times larger pT range • RHIC with current detectors (+ upgrades) • Sufficient pT reach • Sufficient PID for associated particles • What is needed is integrated luminosity! Region of interest for associated particles up to pT ~ 5 GeV Axel Drees

  26. Estimates for g-jet Tomography • Rapidly falling cross section with rapidity: • Assume ~ 1000 events required for statistical g-jet correlation • 40x design luminosity Inclusive direct g today • y max g-pT (GeV) • 0 23 • 1 21 • 2 15 • 3 8 Detector + luminosity upgrades Need to extend pT range not obvious! Hadron pid ~ 4 GeV seems sufficient! Axel Drees

  27. RHIC Heavy Ion Collisions Expected whole vertex minbias event rate [Hz] T. Roser, T. Satogata Low Energy Running at RHIC • Physics goals: • Search for critical point  bulk hadron production and fluctuations • Requires moderate luminosity • can maybe be done in next years • Chiral symmetry restoration  dilepton production • Requires highest possible luminosity, i.e. electron cooling • Luminosity estimate with electron cooling • Assume 4 weeks of physics each, 25% recorded luminosity and sufficient triggers • 20 GeV  109 events • 2 GeV  107 events • CERES best run ~ 4x107 events • NA60 In+In ~ 1010 sampled events Increase by factor 100 with electron cooling Very strong low energy dilepton program possible at RHIC Axel Drees

  28. Beyond PHENIX and STAR upgrades? • Do we need (a) new heavy ion experiment(s) at RHIC? • Likely, if it makes sense to continue program beyond 2020 • Aged mostly 25 year old detectors • Capabilities and room for upgrades most likely exhausted • Delivered luminosity leaves room for improvement • Nature of new experiments unclear! • Specialized experiments • 4p multipurpose detector …. “Die Eierlegendewollmilchsau” • Key to future planning: • First results from RHIC upgrades • Detailed jet tomography, jet-jet and g-jet • Heavy flavor (c- and b-production) • Quarkonium measurments (J/, ’ , ) • Electromagnetic radiation (e+e- pair continuum) • Status of low energy program • Quantitative tests at LHC of models that describe RHIC data • Validity of saturation picture • Does ideal hydrodynamics really work • Scaling of parton energy loss • Color screening and recombination New insights and short comings or failures of RHIC detectors will guide planning on time scale 2010-12 Axel Drees

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