Marzia Rosati [email protected]

Iowa State University

Marzia Rosati - ISU

Third Workshop on Quarkonium IHEP, Beijing China October 15, 2004

1

SPS RHIC LHC

Hunting the Quark Gluon Plasma by Measuring Quarkonium

CERN, Geneva BNL, New York CERN, Geneva Pb+Pb Au+Au Pb+Pb 158 AGeV 100+100 GeV 3.3 + 3.3 TeV

SPS

4

RHIC QGP LHC hadron gas

T C

~ 170 MeV temperature

  

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

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Charmonium as a Probe of QGP

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

c c Color Screening

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The NA50 experiment

Marzia Rosati - ISU

A closed-geometry muon spectrometer experiment

4

J/

y

suppression from p-A to Pb-Pb collisions



The J/

y

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



anomalous suppression

Marzia Rosati - ISU

……… Lots of open questions



NA60

5

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

silicon telescope in a 2.5 T dipole beam tracker ZDC targets Z-vertex of the interaction determined by the pixel telescope with ~ 200 µm accuracy muon trigger and tracking hadron absorber Vertex transverse coordinates determined with better than 20 m m accuracy from the pixel telescope and beam tracker Indium beam 158 A GeV 7 In targets Beam tracker station target box windows

z-vertex (cm)

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J/ y production in Indium-Indium collisions Background

Charm J/

y after muon track matching s (J/ y ) : 105  70 MeV matching rate ~ 70% y

’ DY

A multi-step fit (max likelihood) is performed: a) M > 4.2 GeV : normalize the DY b) 2.2

Marzia Rosati - ISU

DY yield = 253 1964 ± ± 16 126 in range 2.9

– 4.5 GeV J/ y yield = 35626 ± 361

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J/ y / Drell-Yan in Indium-Indium collisions B s (J/ y) / s (DY) = 19.6 ± 1.3

for L = 6.8 fm or N part = 128  0.85 ± 0.06

w.r.t. the normal nuclear absorption all data rescaled to 158 GeV Projectile Target J / y L

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

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PHENIX Detector

Event characterization detectors in middle Two central arms for measuring hadrons, photons and electrons Two forward arms for measuring muons

J/

y

ee in central arms J/

ymm

: forward arms

|  |  p e  0.35 0.2 GeV/c muon measurement in range: 1.2 < | p m   | < 2.4 2 GeV/c

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J/

Y

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/ Y , Y ',.. states Base line for pA and AA

p(d)-A : study of "normal nuclear effects": shadowing and energy loss

 Nuclear dependence of s (J/ Y ): A   Base line for AA or s abs (nuclear absorption)

A-A : study of "medium effect" in high density matter

  J/ Y J/ Y suppression : signature of QGP (Matsui/Satz) formation by c quark coalescence?

 Comparisons between various collision species are very important.

 Studies done via both dielectron and dimuon channels in PHENIX.

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J/

Y

in Run 2 p-p Collisions

m

+

m

– e + e – Results consistent with shapes from various models and PDF.

Take the PYTHIA shape to extract our cross section Phys.Rev.Lett.92, 051802,2004 Integrated cross-section : 234 ± 36 (stat) ± 34 (sys) ± 24(abs) μb

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d-Au Collisions

Eskola, Kolhinen, Vogt hep-ph/0104124

South Muon Arm North Muon Arm d    Central Arm

PHENIX μ, North PHENIX

m

, SOUTH PHENIX e



PHENIX measurements cover different ranges of the Au parton momentum fraction where shadowing and anti-shadowing are expected All expected to see p T broadening dE/dx not expected to be significant effect at RHIC energies Overall absorption expected

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Au

J/

Y

in Run 3 d-Au Collisions

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

d-Au m + m m ± m ± North Arm dAu 780 J/ψ’s s ~ 165 MeV   combinatorial background is subtracted using the like-sign pairs physical background (open charm/Drell-Yan) is fitted using an exponential

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Cross section versus p T

J/ Y  m + m Low x 2 ~ 0.003

J/ Y  m + m High x 2 ~ 0.09



=

dAu –

pp 1.77 ± 0.35 GeV 2 1.29 ± 0.35 GeV 2 (preliminary)

Marzia Rosati - ISU

p T is broadened for dAu

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dAu/pp versus p

T p T broadening comparable to lower energy (



s = 39 GeV in E866)

s

dA

 s

pp

 2  197 ) 

Marzia Rosati - ISU

Low x 2 ~ 0.003

High x 2 ~ 0.09

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J/

Y

Rapidity Distribution in dAu and pp

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dAu/pp versus rapidity

R dA

Low x 2 ~ 0.003

(shadowing region)

 compared to lower  s

1 st J/ ψ’s at large negative rapidity!

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

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)

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Run2 AuAu

Phys.Rev.C69, 014901,2004

 y = 1.0

Coalescence model (Thews et al)  y = 4.0

Stat. Model (Andronic et al.) Absorption model (Grandchamp et al.) 

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

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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 mm regions is needed.

• 2004 AuAu run: ~50 times more data (than RUN2) and we already see c lear J/ Y signals

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Near future at RHIC

 

Full exploration of J/

Y

production versus “N binary ” 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

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PHENIX Upgrade



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



Development of required Si tracking for PHENIX well underway

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RHIC-II Luminosity Upgrade

 RHIC-II: 

L

= 5 · 10 32 cm -2 s -1 (pp) 

L

= 7-9 · 10 27 cm -2 s -1 = 7-9 mb -1 s -1 (AuAu)  hadr. min bias: 7200 mb 8 mb -1 s -1 = 58 kHz  30 weeks, 50% efficiency  

L

dt = 80 nb -1  100% reconstruction efficiency  Assume here: s AA = s pp (AB)  

Au+Au, 30 weeks, 50% efficiency produced number of events

 2.7

· 10 8 J/ Y  1 · 10 7 Y ’    170100  (1S) 29700  (2S) 32400  (3S)

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

d



Marzia Rosati - ISU

Extrapolation of RHIC results favors low values

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LHC Heavy Ions

J/

y 

Marzia Rosati - ISU

ALICE e + e 2.1x10

1.4x10

4 4 ALICE μ + μ 8.0x10

5 5.0x10

3 CMS 3.7x10

4 2.6x10

4 ATLAS 2.5x10

4 2.1x10

4

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Summary



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

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