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, 2008 1Strangeness in Quark Matter 2008

CMS Heavy-Ion Program

October 6-10, 2008

D. d’Enterria et al. (eds.), CERN-LHCC-2007-009, J. Phys. G 34, 2307-2455 (2007)

Heavy-Ion Institutions

Adana Athens Auckland Budapest-Eötvös L. CERN Budapest-KFKIU.I. Chicago ChonbukColorado DavisDemokritos Ioannina Iowa KansasKorea Univ. Lisbon Los Alamos LyonMaryland MITMinnesota 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, ...• dNch/dη, Low pT spectra, Elliptic flow, …

– Hard Probes• Color charge density, Transport coefficient, QCD εc & Tc ,

Tomography, …• High pT spectra, jets, or Z-jet correlations,

Quarkonia, …– UPC

• Photoproduction of →l+l-

3. Summary

October 6-10, 2008 3Strangeness in Quark Matter 2008

October 6-10, 2008 4Strangeness in Quark Matter 2008

LHC: New Energy Frontier

October 6-10, 2008

AGS SPS RHIC LHC

sNN (GeV) 5 20 200 5500

Increasing Factor x4 x10 x28

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, 2008

32

0

GeV/fm 10)(

1

d

dE

RT

Bjorken

fm/c) 004.0(~ /2fm/c 1~with 0 R

6Strangeness in Quark Matter 2008

Production Rate at LHC

October 6-10, 2008 7Strangeness in Quark Matter 2008

October 6-10, 2008

CASTORCASTOR

T2T2

Collar Collar shieldingshielding

Forward DetectorsForward Detectors

(5.2 < < 6.5)

TOTEMTOTEM

ZDCZDC

(5.3 < < 6.7)

(z = 140 m)

BeamsBeams

EMEM

HADHADMUON BARRELDrift Tubes & RPCsm≈50 MeV at 10 GeV/c2

SUPERCONDUCTINGCOILS

IRON YOKE

TRACKERSi Pixels & StripsΔp/p ≈1-2% Occupancy < 2% for central Pb+Pb

Total weight : 12,500 tOverall diameter : 15 mOverall length : 21.6 mMagnetic field : 4 Tesla

HCALCu-ScintillatorSampling

ECALPbWO4 Crystals

MUON ENDCAPSCathode 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

CASTOR 5.2 6.5

ZDC 8.3 for neutrals

x~ⅹ(1/40) of RHIC (<10-4 measurable)Qs

2 ~ⅹ3 of RHIC 9Strangeness in Quark Matter 2008

View of Barrel

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

Endcap Disks

October 6-10, 2008 11Strangeness 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 PixelsOccupancy < 2% at dNch

/dη=5000

Estimation of the Gluon Density Does the Gluon Saturation Exist?Color Glass Condensate (CGC)

Pseudorapidity

Mult

iplic

ity d

Nch

/d

C. Smith, CMS-NOTE-2003-015

13Strangeness in Quark Matter 2008

Hadron Spectra at Low pT

October 6-10, 2008

Rel. pT Resolution=2-3%

Tracking: Pixel-Triplet Algotithm

Efficiency Pixel only Fake Rate<10%

Acceptance

F. Sikler, CMS-NOTE-2006-100 & 101

14Strangeness in Quark Matter 2008

Hadron Spectra at Low pT

October 6-10, 2008

PID by Using the Gaussian Unfolding Method for dE/dx

Hadron ChemistryExpansion DynamicsEquation-of-StateStrangeness Production

Pix

els

+S

trip

s

pT [GeV/c]

,...,,,,,,0 KKS

F. Sikler, CMS-NOTE-2006-100 & 101

15Strangeness in Quark Matter 2008

Elliptic Flow

October 6-10, 2008

I. Lohkin et al., CMS-NOTE-2003-019

HydrodynamicsEquation-of-StateViscosity of Fluid

G. Eyyubova et al., CMS-NOTE-2007-004

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-2006-099Level 1 (Muon Chambers+Calorimeters)

High-Level Triggers (high ET-jet, γ, e, μ)• 12k CPU 1.8 GHz ~ 50 Tflops ( 2 RCF)ⅹ ⅹ• Run “offline algorithm” on every Pb+Pb event• Significantly enhanced statistics for hard processes (see the right figure)

High-Level Trigger Pb+Pb p+p

Input Event Rate 3 kHz (8 kHz peak) 100 kHz

Output Bandwidth 225 MByte/sec 225 MByte/sec

Output Rate 10 – 100 Hz 150 Hz

Rejection 97-99.7% 99.85%

Level 1 Pb+Pb p+p

Collision Rate 3 kHz (8 kHz peak) 1 GHz

Event Rate 3 kHz (8 kHz peak) 32 MHz

Output Bandwidth 100 GByte/sec 100 GByte/sec

Rejection None 99.7%

ET reach x2

jets

Pb+Pb at 5.5 TeV

design luminosity

18Strangeness in Quark Matter 2008

Particle Spectra at High pT

October 6-10, 2008M

om

entu

mre

solu

tion

[%]

Perc

enta

ge [

%]

Medium Density

Transport Coefficient

Charged particle spectra up to pT ~300 GeV/c(High ET HLT)

C. Roland, CMS-NOTE-2006-001 & 110

19Strangeness in Quark Matter 2008

Full Jet Reconstruction

October 6-10, 2008

Iterative cone(R=0.5)+Background subtraction

High efficiency and purity for ET>50 GeV

Good energy resolution for ET>100 GeV

I. Vardanyan et al., CMS-NOTE-2006-050

Jet spectra up to ET ~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 ina Pb+Pb event,after background subtraction

20Strangeness in Quark Matter 2008

Photon-Tagged Jets

October 6-10, 2008

* (or Z0) →μ+μ- is being also

studied

associated

hadrons

jet

g (q)g (q)

g (q)

Photons-Tagging parton energy-Sophisticated isolation/shape cut technique was developed

(S/B was improved by about 15)

-ET(>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 pT

Enhancement at low pT

22Strangeness in Quark Matter 2008

Heavy Flavor (J/)

October 6-10, 2008

S/B = 1.2J/ψ=35 MeV/c2

BARREL+Endcaps

dNch /dη|η=0 =2500

pT (G

eV

/c)

The best +- mass resolution at LHC

Pb+Pb (0.5 nb-

1)

NJ/~1.8×105

O. Kodolova and M. Bedjidian, CMS-NOTE-2006-116

• J/ψ Suppression: RHIC≈SPS (!)

• Regeneration↑≈ Screening↓(?)

• J/ψ may survive up to 2 TC (?)

• Question at LHC: Further suppression or Enhancement?

The J/ spectra beyond40 GeV/cusing HLT

23Strangeness in Quark Matter 2008

Heavy Flavor ()

October 6-10, 2008

dNch /dη|η=0 =2500

pT (

GeV

/c)

- The spectra beyond 40 GeV/c using HLT

N~2.5 ⅹ104

σm=54 MeV/c2 for BARREL → σm=90 MeV/c2 for BARREL+ENDCAP (The best +- mass resolution at LHC)

O. Kodolova and M. Bedjidian, CMS-NOTE-2006-116

24Strangeness 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)

)HERA(3

TeV/u 1

)HI:LHC(max

p

Pb

s

s

)LEP(

GeV 160

)HI:LHC(max

s

s

~500 ’s/0.5nb-1 Unexplored xG(x,Q2) 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 pT≥100 MeV/c with excellent particle identification.

October 6-10, 2008 26Strangeness in Quark Matter 2008