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High T QCD at RHIC: Hard Probes

High T QCD at RHIC: Hard Probes. Fundamental open questions for high T QCD Nature of matter created at RHIC Critical Point Hadronization Rapid thermalization Experimental quest for answers Status of key experimental probes limitations of progress and solutions with upgrades of RHIC

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High T QCD at RHIC: Hard Probes

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  1. High T QCD at RHIC: Hard Probes • Fundamental open questions for high T QCD • Nature of matter created at RHIC • Critical Point • Hadronization • Rapid thermalization • Experimental quest for answers • Status of key experimental probes • limitations of progress and solutions with upgrades of RHIC • Ongoing and planed improvements to RHIC • Time line, detector and accelerator upgrades (RHIC II) • Summary

  2. Study high T and r QCD in the Laboratory 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 AGS and SPS Ongoing program at RHIC 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

  3. V2 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

  4. Fundamental Questions and our experimental approach at RHIC • Is the quark-gluon plasma the most perfect liquid? If not, what are its quasi particles? • Hard penetrating probes with highest possible luminosity at top RHIC energies • Excitation function and flavor dependence of collective behavior • Is there a critical point in the QCD phase diagram and where is it located? • Low energy scan of hadron production • Low energy scan of dilepton production with highest possible luminosity • How does the deconfined matter transform into hadrons? • Flavor dependence of spectra and collective flow • How are colliding nuclei converted into thermal quark-gluon plasma so rapidly? • Hard probes at forward rapidity Question formulated at QCD workshop, Washington DC 12/2006 Axel Drees

  5. Fundamental Question (I) • Is the quark-gluon plasma the most perfect liquid? If not, what are its quasi particles? • What are the properties of new state of matter? • Temperature, density, viscosity, speed of sound, diffusion coefficient, transport coefficients …. • If it’s a fluid: What is the nature a relativistic quantum fluid? • If not: What is it and what are the relevant degrees of freedom? Key are precision measurements with hard probes and of collective behavior currently not accessible at RHIC  RHIC upgrades: improved detectors and increased luminosity Axel Drees

  6. 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

  7. 0-12% STAR trigger 2.5-4 GeV, partner 1.0-2.5 GeV hydro vacuum fragmentation reaction of medium 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 Answers will come from jet tomography (g-jet): single, two and three particle analysis Progress limited by: statistics (pT reach)  increase luminosity and/or rate capability kinematic coverage  increase acceptance & add pid • Which observables are sensitive to details of energy loss mechanism? • What is the energy loss mechanism? • Do we understand relation between energy loss and energy density? • What phenomena relate to reaction of media to probe? Axel Drees

  8. Jet Tomography at RHIC II Medium reacting hadron < 5 GeV W.Vogelsang NLO RHIC II L= 20nb-1 LHC: 1 month run • or p0 trigger without RHIC II <z> ~ 0.1 for particles in recoil jet with RHIC II • RHIC II luminosities will give jets up to 50 GeV • separation of medium reaction and energy loss • sufficient statistics for 3 particle correlations pT > 5 GeV • 2-3 particle correlations with identified particles Axel Drees

  9. Hard Probes: Open Heavy Flavor Electrons from c/b hadron decays • Status • Calibrated probe? • pQCD under predicts cross section by factor 2-5 • Factor 2 experimental differences in pp must be resolved • Charm follows binary scaling • Strong medium effects • Significant charm suppression • Significant charm v2 • Upper bound on viscosity ? • Little room for bottom production • Limited agreement with energy loss calculations • What is the energy loss mechanism? • Where are the B-mesons? Answers expected from direct charm/beauty measurements Progress limited by: no b-c separation  decay vertex with silicon vertex detectors statistics (BJ/)  increase luminosity and/or rate capability Axel Drees

  10. X PHENIX VXT ~2 nb-1 D Au Au D B J/ p K X e e Direct Observation of Charm and Beauty m ct GeV mm D0 1865 125 D± 1869 317 B0 5279 464 B± 5279 496 • Detection options with vertex detectors: • Beauty and low pT charm through displaced e and/or m • Beauty via displaced J/ • High pT charm through D   K e RHIC II increases statistics by factor >10 Axel Drees

  11. 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 RAA • Is the J/y screened or not? • Can we really extract screening length from data? J/y Answers require “quarkconium” spectroscopy Progress limited by: statistics (’, )  increase luminosity and/or rate capability Axel Drees

  12. Quarkonium and Open Heavy Flavor Compiled by T.Frawley RHIC II 20 nb-1 LHC on month • LHC relative to RHIC • Luminosity ~ 10% • Running time ~ 25% • Cross section ~ 10-50x • ~ similar yields! * large background ** states maybe not resolved *** min. bias trigger **** pt > 3 GeV Will be statistics limited at RHIC II (and LHC!) Axel Drees

  13. Fundamental Questions (III)  with TOF barrel • How does the deconfined matter transform into hadrons? • Status: • Elliptic flow (v2) • v2 of mesons and baryons scale with constituent quark number • Evidence for deconfined quarks • Hadronisation via recombination of constituent quarks in QGP STAR AuAu 62.4 GeV Progress from s and flavor dependence of collective flow Limited by: flavor detection capabilities s, c, b mesons and baryons  vertex detectors and extended particle ID Axel Drees

  14. eRHIC RHIC LHC FAIR Fundamental Questions (IIII) • How are colliding nuclei converted into thermal quark-gluon plasma so rapidly? • Initial state and entropy generation. • What is the low x cold nuclear matter phase? • Status: • Intriguing hints for CGC (color glass condensate) at RHIC • Bulk particle multiplicities • “mono jets” at forward rapidity STAR Answers at RHIC from hard probes at forward rapidity, ultimately EIC needed Progress at RHIC limited by: detection capabilities  forward detector upgrades Axel Drees

  15. Long Term Timeline of Heavy Ion Facilities 2009 2012 2015 2006 RHIC Vertex tracking, large acceptance, rate capabilities PHENIX & STAR upgrades electron cooling “RHIC II” electron injector/ring “e RHIC” LHC FAIR Phase III: Heavy ion physics Axel Drees

  16. STAR forward meson spectrometer DAQ & TPC electronics full ToF barrel heavy flavor tracker barrel silicon tracker forward tracker PHENIX hadron blind detector muon Trigger silicon vertex barrel (VTX) forward silicon forward EM calorimeter RHIC Upgrades On going effort with projects in different stages Accelerator upgrades Detector upgrades EBIS ion source Electron cooling (x10 luminosity) by 2008 • at 200 GeV extra x10 • Au+Au ~40 KHz event rate Electron cooling at <20 GeV • Additional factor of 10 • Au+Au 20 GeV ~15 KHz event rate • Au+Au 2 GeV ~150 Hz event rate Completed, on going, proposal submitted, in preparation Axel Drees

  17. Fundamental Questions and our experimental approach at RHIC • Is the quark-gluon plasma the most perfect liquid? If not, what are its quasi particles? • Hard penetrating probes with highest possible luminosity at top RHIC energies • Excitation function and flavor dependence of collective behavior • Is there a critical point in the QCD phase diagram and where is it located? • Low energy scan of hadron production • Low energy scan of dilepton production with highest possible luminosity • How does the deconfined matter transform into hadrons? • Flavor dependence of spectra and collective flow • How are colliding nuclei converted into thermal quark-gluon plasma so rapidly? • Hard probes at forward rapidity Key measurements and many precision measurements unavailable at RHIC today! Progress requires: Improved detectors (STAR and PHENIX) vertex tracking, large acceptance, rate capability Luminosity upgrade (RHIC II) electron cooling for all energies Improved theoretical guidance phenomenological tools (e.g. 3-D viscous hydro) lattice QCD (e.g. finite density) new approaches (e.g. gauge/gravity correspondence) Question formulated at QCD workshop, Washington DC 12/2006 Axel Drees

  18. Backup Axel Drees

  19. 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) • Jet tomography: measurements and capabilities complementary • RHIC: large calorimeter and tracking coverage with PID in few GeV range • Extended pT range at LHC • Charm measurements: favorable at RHIC • Abundant thermal production of charm at LHC, no longer a penetrating probe • Large contribution from jet fragmentation and bottom decay • Charm is a “light quark” at LHC • 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 • Rates about equal; LHC 10-50 s, 10% luminosity, 25% running timer • Low mass dileptons: challenging at LHC • Huge irreducible background from charm production at LHC Axel Drees

  20. 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 20 year old detectors • Capabilities and room for upgrades exhausted • Delivered luminosity leaves room for improvement • Nature of new experiments unclear at this point! • Specialized experiments or 4p multipurpose detector ??? • 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 • Tests of models that describe RHIC data at LHC • Validity of saturation picture • Does ideal hydrodynamics really work • Scaling of parton energy loss • Color screening and recombination New insights and short comings of RHIC detectors will guide planning on time scale 2010-12 Axel Drees

  21. e- g* g e+ g Fundamental Questions (I & II) • Key probe: electromagnetic radiation: • No strong final state interaction • Carry information from time of emission to detectors • g and dileptons sensitive to highest temperature of plasma • Dileptons sensitive to medium modifications of mesons • (only known potential handle on chiral symmetry restoration!) • Status • First indication of thermal radiation at RHIC • Strong modification of meson properties • Precision data from SPS, emerging data from RHIC • Theoretical link to chiral symmetry restoration remains unclear NA60 • Can we measure the initial temperature? • Is there a quantitative link from dileptons to chiral symmetry resoration? Answers will come with more precision data  upgrades and low energy running Axel Drees

  22. RHIC II Accelerator upgrades • EBIS ion source • ~30% higher e with U+U • Luminosity increase at 200 GeV • x4 above design achieved by 2008 • Electron cooling at 200 GeV extra x10 • Au+Au ~40 KHz event rate • Electron cooling at <20GeV • Additional factor of 10 • Au+Au 20 GeV ~15 KHz event rate • Au+Au 2 GeV ~150 Hz event rate RHIC Heavy Ion Collisions Increase by additional factor 10 with electron cooling Expected whole vertex minbias event rate [Hz] T. Roser, T. Satogata Axel Drees

  23. Quarkonium and Open Heavy Flavor 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! Will be statistics limited at RHIC II (and LHC!) * large background ** states maybe not resolved *** min. bias trigger **** pt > 3 GeV Axel Drees

  24. 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

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

  26. 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

  27. 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

  28. 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

  29. 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

  30. 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

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