Byungsik Hong (Korea University) for the Collaboration Strangeness in Quark Matter 2008 Tsinghua Univ., Beijing, China Exploring High-Density QCD Matter with CMS/LHC October 6-10, 20081Strangeness in Quark Matter 2008

CMS Heavy-Ion Program October 6-10, 2008 D. d’Enterria et al. (eds.), CERN-LHCC , J. Phys. G 34, (2007) Heavy-Ion Institutions Adana Athens Auckland Budapest-Eötvös L. CERNBudapest-KFKI U.I. Chicago Chonbuk ColoradoDavis Demokritos Ioannina Iowa Kansas Korea Univ. Lisbon Los Alamos Lyon Maryland MIT Minnesota Moscow Mumbai U. of Seoul Vanderbilt Zagreb ~25 Institutions ~100 Collaborators 2Strangeness in Quark Matter 2008

Contents 1.Introduction –Physics motivation and the CMS detector 2.CMS Capability for Heavy-Ion Physics –Soft Probes Hydrodynamics, QCD EoS, Medium viscosity,... dN ch /dη, Low p T spectra, Elliptic flow, … –Hard Probes Color charge density, Transport coefficient, QCD ε c & T c, Tomography, … High p T spectra, jets,  or    Z   -jet correlations, Quarkonia, … –UPC Photoproduction of  → l + l - 3.Summary October 6-10, 20083Strangeness in Quark Matter 2008

October 6-10, 20084Strangeness in Quark Matter 2008

LHC: New Energy Frontier October 6-10, 2008 AGSSPSRHICLHC  s NN (GeV) Increasing Factorx4x10x28 y range  1.6  3.0  5.3  8.6 LHC energies are far 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! 5Strangeness in Quark Matter 2008

Energy Density at LHC October 6-10, 20086Strangeness in Quark Matter 2008

Production Rate at LHC October 6-10, 20087Strangeness in Quark Matter 2008

October 6-10, 2008 CASTOR T2 Collarshielding Forward Detectors (5.2 <  < 6.5) TOTEM ZDC (5.3 <  < 6.7) (z =  140 m) Beams EM HAD MUON BARREL Drift Tubes & RPCs  m ≈50 MeV at 10 GeV/c 2 SUPERCONDUCTING COILS IRON YOKE TRACKER Si Pixels & Strips Δp/p ≈1-2% Occupancy < 2% for central Pb+Pb Total weight : 12,500 t Overall diameter : 15 m Overall length : 21.6 m Magnetic field : 4 Tesla HCAL Cu-Scintillator Sampling ECAL PbWO 4 Crystals MUON ENDCAPS Cathode Strip Chambers & Resistive Plate Chambers (RPCs) CMS Detector 8Strangeness in Quark Matter 2008

CMS Acceptance October 6-10, 2008 HCAL (Barrel+Endcap+Forward) Large Range of Hermetic Coverage Silicon and μ Tracker  2.4 ECAL  3.0 HCAL  5.2 CASTOR5.2  6.5 ZDC  8.3 for neutrals x ~ⅹ(1/40) of RHIC (<10 -4 measurable) Q s 2 ~ⅹ3 of RHIC 9Strangeness in Quark Matter 2008

View of Barrel October 6-10, Strangeness in Quark Matter 2008

Endcap Disks October 6-10, Strangeness in Quark Matter 2008

October 6-10, 2008 Soft Probes of QCD Matter in CMS 12Strangeness in Quark Matter 2008

Charged Particle Multiplicity October 6-10, 2008 Total 66M Si Pixels Occupancy < 2% at dN ch /dη=5000 Estimation of the Gluon Density Does the Gluon Saturation Exist? Color Glass Condensate (CGC) Pseudorapidity  Multiplicity dN ch /d  C. Smith, CMS-NOTE Strangeness in Quark Matter 2008

Hadron Spectra at Low p T October 6-10, 2008 Rel. p T Resolution=2-3% Tracking: Pixel-Triplet Algotithm Efficiency Pixel only Fake Rate<10% Acceptance F. Sikler, CMS-NOTE & Strangeness in Quark Matter 2008

Hadron Spectra at Low p T October 6-10, 2008 PID by Using the Gaussian Unfolding Method for dE/dx Hadron Chemistry Expansion Dynamics Equation-of-State Strangeness Production Pixels+Strips p T [GeV/c] F. Sikler, CMS-NOTE & Strangeness in Quark Matter 2008

Elliptic Flow October 6-10, 2008 I. Lohkin et al., CMS-NOTE Hydrodynamics Equation-of-State Viscosity of Fluid G. Eyyubova et al., CMS-NOTE Non-flow systematic uncertainties not included Reaction Plane Resolution 16Strangeness in Quark Matter 2008

October 6-10, 2008 Hard Probes of QCD Matter in CMS 17Strangeness in Quark Matter 2008

High-Level Trigger October 6-10, 2008 M. Ballitjin, C. Loizides, G. Roland, CMS-NOTE Level 1 (Muon Chambers+Calorimeters) High-Level Triggers (high E T -jet, γ, e, μ) 12k CPU ⅹ 1.8 GHz ~ 50 Tflops ( ⅹ 2 RCF) Run “offline algorithm” on every Pb+Pb event Significantly enhanced statistics for hard processes (see the right figure) High-Level Trigger Pb+Pbp+p Input Event Rate3 kHz (8 kHz peak)100 kHz Output Bandwidth225 MByte/sec Output Rate10 – 100 Hz150 Hz Rejection %99.85% Level 1 Pb+Pbp+p Collision Rate3 kHz (8 kHz peak)1 GHz Event Rate3 kHz (8 kHz peak)32 MHz Output Bandwidth100 GByte/sec RejectionNone99.7% E T reach x2 jets Pb+Pb at 5.5 TeV design luminosity  18Strangeness in Quark Matter 2008

Particle Spectra at High p T October 6-10, 2008 Momentum resolution [%] Percentage [%] Medium Density Transport Coefficient Charged particle spectra up to p T ~300 GeV/c (High E T HLT) C. Roland, CMS-NOTE & Strangeness in Quark Matter 2008

Full Jet Reconstruction October 6-10, 2008 Iterative cone(R=0.5)+Background subtraction High efficiency and purity for E T >50 GeV Good energy resolution for E T >100 GeV I. Vardanyan et al., CMS-NOTE Jet spectra up to E T ~500 GeV Jet Quenching Effect by using True Jets Pb+Pb (0.5 nb -1 : 1 year of running) Min. Bias HLT 100 GeV jet in a Pb+Pb event, after background subtraction 20Strangeness in Quark Matter 2008

Photon-Tagged Jets October 6-10, 2008  * (or Z 0 ) →μ + μ - is being also studied  associated hadrons jet g (q)   Photons -Tagging parton energy -Sophisticated isolation/shape cut technique was developed (S/B was improved by about 15) -E T (  >100 (or 70) GeV C. Loizides, QM08 How is the energy loss distributed in the jet fragmentation cone? 21Strangeness in Quark Matter 2008

Photon-Tagged Jets October 6-10, 2008 Reconstructed FF agrees with the MC FF  Require the back-to-back  -jet correlation by  ( ,jet) > 3 rad. Depletion at high p T Enhancement at low p T 22Strangeness in Quark Matter 2008

Heavy Flavor (J/  ) October 6-10, 2008 S/B = 1.2  J/ψ =35 MeV/c 2 BARREL+ Endcaps dN ch /d η| η=0 = 2500 p T (GeV/c)  The best  +  - mass resolution at LHC Pb+Pb (0.5 nb -1 ) N J/  ~1.8×10 5 O. Kodolova and M. Bedjidian, CMS-NOTE J/ψ Suppression: RHIC ≈ SPS (!) Regeneration↑ ≈ Screening↓(?) J/ψ may survive up to 2 T C (?) Question at LHC: Further suppression or Enhancement? The J/  spectra beyond 40 GeV/c using HLT 23Strangeness in Quark Matter 2008

Heavy Flavor (  ) October 6-10, 2008 dN ch /d η| η=0 = 2500  p T (GeV/c) - The  spectra beyond 40 GeV/c using HLT N  ~2.5 ⅹ10 4 σ m =54 MeV/c 2 for BARREL → σ m =90 MeV/c 2 for BARREL+ENDCAP (The best  +  - mass resolution at LHC) O. Kodolova and M. Bedjidian, CMS-NOTE Strangeness in Quark Matter 2008

 Production in UPC October 6-10, 2008 Strong E&M fields due to the coherent action of 82 protons (   max ~80 GeV) ~500  ’s/0.5nb -1 Unexplored xG(x,Q 2 ) region 25Strangeness in Quark Matter 2008

Summary 1.The CMS detector is versatile not only for pp, but also for heavy-ion collisions. 2.The CMS high-resolution trackers, calorimeters, and muon chambers cover almost 4  phase space. 3.The CMS detector can measure various hard probes with the best resolution at the LHC. 4.The CMS detector can also measure soft hadrons for p T ≥100 MeV/c with excellent particle identification. October 6-10, Strangeness in Quark Matter 2008