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Exploring High-Density QCD Matter with CMS/LHC

Exploring High-Density QCD Matter with CMS/LHC. Strangeness in Quark Matter 2008 Tsinghua Univ., Beijing, China. Byungsik Hong (Korea University) for the Collaboration. CMS Heavy-Ion Program. Heavy-Ion Institutions Adana Athens Auckland Budapest-E ötvös L.

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Exploring High-Density QCD Matter with CMS/LHC

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  1. Exploring High-Density QCD Matter with CMS/LHC Strangeness in Quark Matter 2008 TsinghuaUniv., Beijing, China Byungsik Hong(Korea University) for the Collaboration Strangeness in Quark Matter 2008

  2. CMS Heavy-Ion Program Heavy-Ion Institutions Adana Athens Auckland Budapest-Eötvös L. CERN Budapest-KFKI U.I. Chicago Chonbuk Colorado Davis Demokritos Ioannina Iowa Kansas Korea Univ. Lisbon Los Alamos Lyon Maryland MIT Minnesota Moscow Mumbai U. of Seoul Vanderbilt Zagreb ~25 Institutions ~100 Collaborators D. d’Enterria et al. (eds.), CERN-LHCC-2007-009, J. Phys. G 34, 2307-2455 (2007) Strangeness in Quark Matter 2008

  3. Contents • Introduction • Physics motivation and the CMS detector • CMS Capabilityfor Heavy-Ion Physics • Soft Probes • Hydrodynamics, QCD EoS, Medium viscosity, ... • dNch/dη, Low pT spectra, Elliptic flow, … • Hard Probes • Color charge density, Transport coefficient, QCD εc & Tc , Tomography, … • High pT spectra, jets, g (or g*, Z0)-jet correlations, Quarkonia, … • UPC • Photoproduction of ¡→l+l- • Summary Strangeness in Quark Matter 2008

  4. Strangeness in Quark Matter 2008

  5. LHC: New Energy Frontier • LHC energies arefar exceeding the range of previous heavy-ion accelerators • Extended kinematic reach for pp, pA, and AA collisions • New properties of the initial state and saturation at mid-rapidity • A hotter, denser, and longer lived partonic matter • Increased cross sections and availability of new hard probes • New energy regime will open a new window on hot and dense QCD matter physics: another large energy jump! Strangeness in Quark Matter 2008

  6. EnergyDensity at LHC Strangeness in Quark Matter 2008

  7. Production Rate at LHC Strangeness in Quark Matter 2008

  8. Forward Detectors CASTOR (5.2 << 6.5) TOTEM Total weight : 12,500 t Collar shielding (5.3 << 6.7) Overall diameter : 15 m Overall length : 21.6 m T2 Magnetic field : 4 Tesla ZDC (z = 140 m) EM HAD Beams CMS Detector SUPERCONDUCTING COILS ECAL PbWO4 Crystals HCAL Cu-Scintillator Sampling IRON YOKE TRACKER Si Pixels & Strips Δp/p ≈1-2% Occupancy < 2% for central Pb+Pb MUON BARREL Drift Tubes & RPCs sm≈50 MeV at 10 GeV/c2 MUON ENDCAPS Cathode Strip Chambers & Resistive Plate Chambers (RPCs) Strangeness in Quark Matter 2008

  9. HCAL (Barrel+Endcap+Forward) CMS Acceptance Large Range of Hermetic Coverage x~ⅹ(1/40) of RHIC (<10-4 measurable) Qs2 ~ⅹ3 of RHIC Strangeness in Quark Matter 2008

  10. View of Barrel Strangeness in Quark Matter 2008

  11. EndcapDisks Strangeness in Quark Matter 2008

  12. Soft Probes of QCD Matter in CMS Strangeness in Quark Matter 2008

  13. Charged Particle Multiplicity Total 66M Si Pixels Occupancy < 2% at dNch /dη=5000 C. Smith, CMS-NOTE-2003-015 MultiplicitydNch /dh Pseudorapidityh Estimation of the Gluon Density Does the Gluon Saturation Exist? Color Glass Condensate (CGC) Strangeness in Quark Matter 2008

  14. Hadron Spectra at Low pT F. Sikler, CMS-NOTE-2006-100 & 101 Tracking: Pixel-Triplet Algotithm Acceptance Rel. pT Resolution=2-3% Pixel only Fake Rate<10% Efficiency Strangeness in Quark Matter 2008

  15. Hadron Spectra at Low pT PID by Using the Gaussian Unfolding Method for dE/dx F. Sikler, CMS-NOTE-2006-100 & 101 Pixels+Strips pT [GeV/c] Hadron Chemistry Expansion Dynamics Equation-of-State Strangeness Production Strangeness in Quark Matter 2008

  16. Elliptic Flow I. Lohkin et al., CMS-NOTE-2003-019 G. Eyyubova et al., CMS-NOTE-2007-004 ReactionPlane Resolution Non-flow systematic uncertainties not included Hydrodynamics Equation-of-State Viscosity of Fluid Strangeness in Quark Matter 2008

  17. Hard Probes of QCD Matter in CMS Strangeness in Quark Matter 2008

  18. High-Level Trigger Pb+Pb at 5.5 TeV design luminosity Level 1 (Muon Chambers+Calorimeters) M. Ballitjin, C. Loizides, G. Roland, CMS-NOTE-2006-099 ET reach x2 jets • High-Level Triggers (high ET-jet, γ, e, μ) • 12k CPUⅹ1.8 GHz ~ 50 Tflops (ⅹ2 RCF) • Run “offline algorithm” on every Pb+Pb event • Significantly enhanced statistics • for hard processes (see the right figure) ¡ Strangeness in Quark Matter 2008

  19. Particle Spectra at High pT C. Roland, CMS-NOTE-2006-001 & 110 Percentage [%] MediumDensity Momentum resolution [%] Charged particle spectra up to pT ~300 GeV/c (High ET HLT) Transport Coefficient Strangeness in Quark Matter 2008

  20. Full Jet Reconstruction Iterative cone(R=0.5)+Background subtraction • Pb+Pb (0.5 nb-1: 1 year of running) • High efficiency • and purity • for ET>50 GeV 100 GeV jet ina Pb+Pb event,after background subtraction HLT Min. Bias • Jet spectra up to ET ~500 GeV • Good energy • resolution • for ET>100 GeV Jet Quenching Effect by using True Jets I. Vardanyan et al., CMS-NOTE-2006-050 Strangeness in Quark Matter 2008

  21. Photon-Tagged Jets g* (or Z0) →μ+μ- is being also studied g g (q) g (q) g (q) jet associated hadrons How is the energy loss distributed in the jet fragmentation cone? • Photons • -Tagging parton energy • Sophisticated isolation/shape cut technique was developed • (S/B was improved by about 15) • -ET(g)>100 (or 70) GeV C. Loizides, QM08 Strangeness in Quark Matter 2008

  22. Photon-Tagged Jets • Require the back-to-back g-jet correlation by Df(g,jet) > 3 rad. Reconstructed FF agrees with the MC FF Depletion at high pT Enhancement at low pT Strangeness in Quark Matter 2008

  23. pT (GeV/c) h Heavy Flavor (J/y) O. Kodolova and M. Bedjidian, CMS-NOTE-2006-116 dNch /dη|η=0 =2500 • Pb+Pb (0.5 nb-1) BARREL+ Endcaps The J/y spectra beyond 40 GeV/c using HLT The best m+m- mass resolution at LHC S/B = 1.2 sJ/ψ=35 MeV/c2 NJ/y~1.8×105 • J/ψ Suppression: RHIC≈SPS (!) • Regeneration↑≈ Screening↓(?) • J/ψ may survive up to 2 TC (?) • Question at LHC: Further suppression or Enhancement? Strangeness in Quark Matter 2008

  24. Heavy Flavor (¡) O. Kodolova and M. Bedjidian, CMS-NOTE-2006-116 dNch /dη|η=0 =2500 σm=54 MeV/c2 for BARREL → σm=90 MeV/c2 for BARREL+ENDCAP (The best m+m- mass resolution at LHC) pT (GeV/c) h N¡~2.5 ⅹ104 - The ¡ spectra beyond 40 GeV/c using HLT Strangeness in Quark Matter 2008

  25. ¡ Production in UPC Strong E&M fields due to the coherent action of 82 protons (Egmax~80 GeV) Unexplored xG(x,Q2) region ~500 ¡’s/0.5nb-1 Strangeness in Quark Matter 2008

  26. Summary • The CMS detector is versatile not only for pp, but also for heavy-ion collisions. • The CMS high-resolution trackers, calorimeters, and muon chambers cover almost 4p phasespace. • The CMS detector can measure various hard probes with the best resolution at the LHC. • The CMS detector can also measure soft hadrons for pT≥100 MeV/c with excellent particle identification. Strangeness in Quark Matter 2008

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