marzia rosati mrosati@iastate iowa state university

Marzia Rosati - ISU 1

Marzia [email protected]

Iowa State University

Third Workshop on QuarkoniumIHEP, Beijing ChinaOctober 15, 2004


Hunting the Quark Gluon Plasma

by Measuring Quarkonium

Hunting the Quark Gluon Plasma

by Measuring Quarkonium

SPS CERN, Geneva Pb+Pb 158 AGeV

RHIC BNL, New York Au+Au 100+100 GeV

LHC CERN, Geneva Pb+Pb 3.3 + 3.3 TeV

4

temperature

en

erg

y d

en

sit

y /

T4

TC ~ 170 MeV

LHC

RHICSPS

hadron gas

QGP

New Quarkonium Measurements at SPS: NA60 New Quarkonium Measurements at RHIC: PHENIX Future Opportunities at RHIC and LHC


Charmonium as a Probe of QGPCharmonium as a Probe of QGP

Matsui and Satz predicted J/ production suppression in Quark Gluon Plasma because of color screening

Color Screening

cc


The NA50 experimentThe NA50 experiment

A closed-geometrymuon spectrometerexperiment


NA38/NA50M

easu

red

/ E

xpec

ted

J/ suppression from p-A to Pb-Pb collisionsJ/ suppression from p-A to Pb-Pb collisions

The J/ production is suppressed in Pb-Pb collisions with respect to the yields extrapolated from proton-nucleus data

anomalous suppression

……… Lots of open questions NA60


hadron absorber

muon trigger and tracking

magnetic field

silicon telescopein a 2.5 T dipole

targets

beam trackerZDC

target boxwindows

7 In targets

z-vertex (cm)

Indium beam

158 A GeV

Beam tracker station

Z-vertex of the interaction determined by the pixel telescope with ~ 200 µm accuracy Vertex transverse coordinates determined with

better than 20 m accuracy from the pixel telescope and beam tracker

What’s original in NA60: measuring dimuons in the target region

What’s original in NA60: measuring dimuons in the target region

NA60


J/ yield = 35626 ± 361

J/

’ DY

Background

Charm

A multi-step fit (max likelihood) is performed:a) M > 4.2 GeV : normalize the DYb) 2.2<M<2.5 GeV: normalize the charm (with DY fixed)

c) 2.9<M<4.2 GeV: get the J/ yield (with DY & charm fixed)

DY yield = 253 ± 161964 ± 126 in range 2.9–4.5 GeV

J/ production in Indium-Indium collisions

(J/) : 105 70 MeVmatching rate ~ 70%

after muon track matching

NA60


B (J// (DY) = 19.6 ± 1.3

for L = 6.8 fm or Npart = 128

0.85 ± 0.06 w.r.t. the normal nuclear absorption

all data rescaled to 158 GeV

preliminary

J/ / Drell-Yan in Indium-Indium collisions

J/L

Projectile

Target

L= mean length of the path of the (cc) system through nuclear matter

NA60


Two central arms for measuring hadrons, photons and electrons

Two forward arms for measuring muons

Event characterization detectors in middle

PHENIX DetectorPHENIX Detector

J/ee in central armselectron measurement in

range: || 0.35

pe 0.2 GeV/c

J/ : forward armsmuon measurement in

range:

1.2 < || < 2.4

p 2 GeV/c


J/ Measurement Planned at RHICJ/ Measurement Planned at RHIC

p-p : study of production mechanism and cross sections Color evaporation model, Color singlet model, Color octet model Polarization, Rapidity dependence (electron and muon channels) Production of J/, ',.. states Base line for pA and AA

p(d)-A : study of "normal nuclear effects": shadowing and energy loss Nuclear dependence of (J/): A or abs (nuclear absorption) Base line for AA

A-A : study of "medium effect" in high density matter J/ suppression : signature of QGP (Matsui/Satz) J/ formation by c quark coalescence?

Comparisons between various collision species are very important.Studies done via both dielectron and dimuon channels in PHENIX.


Integrated cross-section : 234 ± 36 (stat) ± 34 (sys) ± 24(abs) μb

e+e–

+–

Results consistent with shapes from various models and PDF.

Take the PYTHIAshape to extract our cross-section

J/ in Run 2 p-p CollisionsJ/ in Run 2 p-p Collisions

Phys.Rev.Lett.92, 051802,2004


d-Au Collisionsd-Au Collisions

PHENIX measurements cover different ranges of the Au parton momentum fraction where shadowing and anti-shadowing are expected

All expected to see pT broadening dE/dx not expected to be significant effect at RHIC energies Overall absorption expected

Eskola, Kolhinen, Vogt hep-ph/0104124

PHENIX μ, North PHENIX , SOUTH

PHENIX e

d Au

North Muon ArmSouth Muon Arm

Central Arm


J/ in Run 3 d-Au CollisionsJ/ in Run 3 d-Au Collisions

combinatorial background is subtracted using the like-sign pairs physical background (open charm/Drell-Yan) is fitted using an exponential

In RUN3, we accumulated ~3nb-1 d-Au collisions.

+-

±±

780 J/ψ’s ~ 165 MeV

North ArmdAu


J/ +- High x2 ~ 0.09

Low x2

~ 0.003

J/ +-

Cross section versus pTCross section versus pT

pT is broadened for dAu

<pT2> =

<pT2>dAu – <pT

2>pp

1.77 ± 0.35 GeV2

1.29 ± 0.35 GeV2

(preliminary)


1972 ppdAHigh x2

~ 0.09

Low x2

~ 0.003pT broadening comparable

to lower energy(s = 39 GeV in E866)

dAu/pp versus pTdAu/pp versus pT


J/ Rapidity Distribution in dAu and pp J/ Rapidity Distribution in dAu and pp


1st J/ψ’s at large negative rapidity!

Low x2 ~ 0.003(shadowing region)

Klein,Vogt, PRL 91:142301,2003 Kopeliovich, NP A696:669,2001

compared to lower s

Data favors (weak) shadowing + (weak) absorption ( > 0.92) With limited statistics difficult to disentangle nuclear effects. We

will need another dAu run! (and more pp data also)

dAu/pp versus rapiditydAu/pp versus rapidity

RdA


Disfavor models with enhancement relative to binary collision scaling. Cannot discriminate between models that lead to suppression relative to binary collision scaling.

Phys.Rev.C69, 014901,2004

Coalescence model (Thews et al)

y = 1.0

y = 4.0Stat. Model (Andronic et al.)

Absorption model (Grandchamp et al.)

Run2 AuAuRun2 AuAu


Simple expectation for AuAu J/ψ’s based on nuclear dependence observed in dAu

Simple expectation for AuAu J/ψ’s based on nuclear dependence observed in dAu

• Renormalize model predictions to dAu measurement (top panel).• Then reverse RdAu and multiply by itself (bottom panel)• Variations between models not too large at mid-rapidity, but substantial in the large negative or positive rapidity regions. Better models (physics understanding) might help, but a higher statistics dAu baseline, especially in the regions is needed.

• 2004 AuAu run:~50 times more data (than RUN2) and we already see c

lear J/ signals


Near future at RHICNear future at RHIC

Full exploration of J/ production versus “Nbinary”

Look forward to future runs with high luminosity where also studies for different collision species and with varying energy can be made

Upcoming run in December 2004 CuCu collisions and long p-p run


PHENIX UpgradePHENIX Upgrade

Ultimately we want to detect open charm “directly” via displaced vertices

Development of required Si tracking for PHENIX well underway


RHIC-II Luminosity UpgradeRHIC-II Luminosity UpgradeRHIC-II:

L = 5·1032 cm-2 s-1 (pp)L = 7-9·1027 cm-2 s-1 = 7-9 mb-1 s-1 (AuAu)hadr. min bias: 7200 mb 8 mb-1 s-1 = 58 kHz30 weeks, 50% efficiency Ldt = 80 nb-1

100% reconstruction efficiencyAssume here: AA = pp (AB)

Au+Au, 30 weeks, 50% efficiency produced number of events 2.7·108 J/ 1·107 ’ 170100 (1S) 29700 (2S) 32400 (3S)


The Physics Landscape: Pb+Pb Collisions SPS->RHIC->LHC

d

Extrapolation of RHIC results favors low values


LHC Heavy IonsLHC Heavy Ions

ALICE e+e- ALICE μ+μ- CMS ATLAS

J/ 2.1x104 8.0x105 3.7x104 2.5x104

1.4x104 5.0x103 2.6x104 2.1x104


SummarySummary

The good and bad news: the phenomenology of charmonium in nuclear collisions is richer than anyone supposed There is enough interesting physics to keep us busy Things are not as simple as first supposed

The goal of the field has shifted from “discovering the quark-gluon plasma” to “characterizing the nuclear medium under extreme conditions” This is a plus – we’ve moved past presupposing how things will

behave and towards measuring and understanding what really happens

Charmonium is a critical probe in this wider effort New data from RHIC and NA60 is right around the corner Experimental program will continue at LHC

marzia rosati mrosati@iastate iowa state university

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