Byungsik Hong (Korea University) for the Collaboration Strangeness in Quark Matter 2008 Tsinghua...

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


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!


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


Production Rate at LHC


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


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


Endcap Disks


October 6-10, 2008

Soft Probes of QCD Matter in CMS


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


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


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


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


October 6-10, 2008

Hard Probes of QCD Matter in CMS


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


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


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


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?


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


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


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


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


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.


Byungsik Hong (Korea University) for the Collaboration Strangeness in Quark Matter 2008 Tsinghua...

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