03/30/2011 Zebo Tang, STAR MTD Workshop, Hefei 1

J/ Results from STAR

Zebo Tang

University of Science and Technology of China (USTC)Center of Particle Physics and Technology

The first Workshop on STAR MTD Production and Related PhysicsHefei, Anhui, China, Marth 30th – April 1st, 2011

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QCD phase diagram

Net Baryon Density

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Outline

• Introduction– J/ as a classic probe of QGP– J/ production mechanism in p+p collisions

• Electron identification and J/ reconstruction

• Results– J/ spectra in p+p collisions– J/-hadron correlation in p+p collisions– J/ suppression in A+A collisions

• J/ with MTD• Summary

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J/ melting in QGP – Signature of deconfinement

J/ dissociation due to color screening Signature of the QGP formation

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QGP thermometer

Quarkonium dissociation temperatures – Digal, Karsch, Satz

?

Plasma thermometer

Dissociation temperature depends on binding energy QGP temperature

Model dependent

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H. Satz, Nucl. Phys. A (783):249-260(2007)

Other effects

J/ suppression at low pT maybe only from excited stats (’, c) F. Karsch, D. Kharzeev and H. Satz, PLB 637, 75 (2006)

60% from direct J/: not suppressed30% c and 10% ’: dissociated

NA50, EPJ39,335NA60, QM05

• Feeddown (sequential suppression)• Cronin effect• Nuclear absorption • Hadronic phase dissociation• Gluon saturation• Formation time effect• …

Precise measurements at broad kinetic range and systems are needed!

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Charmonium production mechanism

NRQCD

Color singlet

Color octet

Color singlet model (CSM), LO

underpredicted CDF data by order of magnitude

Color octet model (COM), LO

good agreement with CDF cross section

disagreement with CDF polarization

LO

Know your reference!LO CSM LO COM

J/3S1

J/

CDF measurement: PRL79,572

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Charmonium production mechanism

NRQCD

Color singlet

Color octet

Color singlet model (CSM), LO

underpredicted CDF data by order of magnitude

Color octet model (COM), LO

good agreement with CDF cross section

disagreement with CDF polarization

CSM*, NLO

better agreement

NNLO* applicable at pT>5-7 GeV/c

COM*

improvement of polarization,

NLO will come, valid at pT>3 GeV/c

Decay feeddown (CDF):

(2s): 7%-15%, slightly increase with pT

c0,1,2: ~30%, slightly decrease with pT

B: Strong pT dependence

LO

Know your reference!

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STAR detector

MRPC ToF BarrelMRPC ToF Barrel

BBC

FPD

FMS

EMC BarrelEMC End Cap

DAQ1000DAQ1000 COMPLETE

Ongoing

MTD

R&D

TPC

HLT

trigger computingFTPC

PMD

2 coverage at mid-rapidity (||<1)

TPC+BEMC+(MRPC-TOF) in this analysis

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Electron identification (TPC only)

With TPC only:• No electron ID at low pT

• Eifficult to get a good electron sample at high pT

• Possible to get a electron sample with reasonable purity at intermediate pT

x sigma deviation from electron dE/dx curve

Note: electron yield is much less than hadrons

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Electron ID (EMC)

Online fast trigger: • Enhance high pT electron• Enhance recorded luminosity

Offline cuts:Matching between EMC and TPCDeposited energy (BTOW)Shower shape (BSMD)

x0.05x0.05)

~5X0

Low pT J/:Intermediate pT electrons (TPC only)High pT J/high pT electron (TPC+EMC) +Intermediate pT electron (TPC only)

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Low-pT J/ signals

200GeV p+pL2 J/ trigger

200GeV d+AuMB trigger

200GeV Cu+CuMB trigger

200GeV Au+AuMB trigger

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High-pT J/ signals

• Tight cuts for correlation study• Spectra in progress

2009

STAR, PRC80, 041902(R), 2009

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J/ spectra in p+p and Cu+Cu at 200 GeV

• Significantly extend pT range of previous measurements in p+p at RHIC to 14 GeV/c

• Agreement of charm measurements between STAR and PHENIX

~3 orders

Online fast trigger is important with limited DAQ rate and Data processing capability

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J/ pT spectra

STAR, PRC80, 041902(R), 2009

J/ xT scaling at high pT: n=5.6±0.2 (close to CS+CO prediction)Soft processes affect low pT J/ production

STAR, PRC80, 041902(R), 2009

Color singlet model: direct NNLO* still miss the high pT part. P. Artoisenet et al., Phys. Rev. Lett.

101, 152001 (2008), and J.P. Lansberg private communication.

LO CS+CO: better agreement with the measurements, leave little room for higher charmonium states and B feeddown. G. C. Nayak, M. X. Liu, and F. Cooper, Phys. Rev. D68, 034003 (2003), and private communication.

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Constrain bottom contribution

• No significant near side J/-hadron azimuthal angle correlation• Correlation show low B contribution (13 5) %

STAR Preliminary

h-h correlation

J/-h correlation

STAR, PRC80, 041902(R), 2009

STAR, PRL95, 152301 (2005)

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Correlations from Run9

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BJ/ / inclusive J/

• Consistent with previous results• No significant beam energy dependence• Can be used to constrain B production

PRC80, 041902(R), 2009

PLB370, 239, 1996PLB200, 380, 1988

PRD71, 032001, 2005

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Associated hadron pT spectra

Near side: Consistent with no associated hadron production Away side: Consistent with h-h correlation away-side seems to come from gluon/light quark fragmentation

STAR, PRL95, 152301 (2005)

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Low-pT J/ in Au+Au 200 GeV

• Model (green band) includes: color screening in QGP, dissociation in hadronic phase, statistical recombination, B → J/ feed-down and formation time effects

• New Au+Au results with minimum inner material soon (5x higher statistics with TOF)

STAR PreliminarySTAR Preliminary

PHENIX: Phys. Rev. Lett. 98, 232301 (2007)

STAR Preliminary

0-20%

20-80%STAR Preliminary

0-20%

20-80%

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STAR, PRC80, 041902(R), 2009

High-pT J/ in Cu+Cu 200 GeV

STAR Cu+Cu 0-20%: RAA(pT>5) = 1.40.40.2 The only hadron measured to be not suppressed at high pT in RHIC Heavy-ion collisions Contrast to open charm. CS vs. CO? CNM effect ？ Formation Time?

A. Adil and I. Vitev, Phys. Lett. B649, 139 (2007), and I. Vitev private communication;S. Wicks et al., Nucl. Phys. A784, 426 (2007), and W. A. Horowitz private communication.

RAA>AdS/CFT+Hydro, 99% C.L. Contrast to AdS/CFT+Hydro prediction 2-component models describes the overall trend

H. Liu, K. Rajagopal and U.A. Wiedemann PRL 98, 182301(2007);T. Gunji, J. Phys.G 35, 104137 (2008)

X. Zhao and R. Rapp, Phys. Lett. B664:253, 2008; Y.P. Liu, et al., Phys.Lett.B678:72-76,2009

Cu is too small?

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82±136

J/ in Au+Au @ 39 GeV

91±224

• Clear signal seen in 39GeV Au+Au with TOF • Expect ~1000 (13) J/ from full MB data• Able to cover pT range (0, 5) GeV/c

• Much higher statistics and recorded integral luminosity at 62 and 200GeV

dE/dx after TOF cut

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Muon Telescope Detector (MTD)

Advantages over electronsno conversionmuch less Dalitz decay contributionless affected by radiative losses in the materials

Trigger capability for low to high pT J/ in central Au+Au collisionsHigh /hadron enhancement

S/B~2 in central Au+Au

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MTD in RHICII era

J/

J/

MTD+HFT:Trigger and topologically reconstruct BJ/, J/

MTD+TOF:J/+ccbar?Charmonium higher states?

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Summary

In 200 GeV p+p collisions Extended previous spectra measurements to 14 GeV/c Large S/B ratio allows correlation study

B has sizeable (not dominant) contribution at high pT

high-pT J/ away side hadron production consistent with gluon/quark fragmentation

In heavy-ion collisions First observation of no suppression for hadron at high pT at STAR in 200GeV Cu+Cu collisions Clear signals seen in 39 GeV Au+Au with TOF, covers pT from 0 to 5 GeV/c

Thank you!It is just a start!

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Extra

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Future dramatic improvement of J / at low pT

EMC+TOF+HFT (large acceptance):

• J/ production

• Different states predicted to melt at different T in color medium

• Charmonia (J/), bottonia ()

Quarkonium dissociation temperatures – Digal, Karsch, Satz

pT (e)>1.5 GeV/c

PHENIX Acceptance: ||<0.35,=2*/2 STAR TOF-Upgrade Acceptance: ||<0.9,=2*

J/ yields from 1 billion minbias Au+Au events: 43.8x10-9/0.040x109*292*0.5*1.8*0.5= 144,0000.3% v2 errorJ/pp N Nbin y RAA

dE/dx after TOF cut

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Detector upgrades: HFT and MTD

Heavy Flavor Tracker:

Muon Telescope Detector:

n>0

STAR Preliminary

Prototype in run VII

e+e- rejection

Topologically reconstructJ/ from B decay

Rejection power: ~16

Muon identification simulation

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Jpsi-h correlation from PYTHIA

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J/ measurements in Heavy Ion Collisions

• Due to color screening, J/ was thought be dissociated in the medium. T. Masui

and H. Satz, Phys. Lett. B178, 416 (1986). • At RHIC, the suppression at low pT is similar to at SPS at similar Npart: recombination due to large charm cross section. P. Braun-Munzinger and J. Stachel, Phys. Lett. B490,196 (2000); L. Grandchamp and R. Rapp, Phys. Lett. B523, 60 (2001); M. I. Gorenstein et al., Phys. Lett. B524, 265 (2002); R. L. Thews, M. Schroedter, and J. Rafelski, Phys. Rev. C63, 054905 (2001); Yan, Zhang and Xu, Phys.Rev.Lett.97, 232301 (2006); PHENIX: Phys.Rev.Lett.98, 232301,2007.

• At SPS, suppression decreases versus pT: Cronin effect , Nuclear absorption and formation time effect. M. C. Abreu et al., Phys. Lett. B499, 85 (2001); X. Zhao, WWND2008; X. Zhao and R. Rapp, hep-ph/07122407; X. Zhu, P. Zhuang, PRC67, 067901(2003)

NA60, QM08

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High pT J/ in heavy ion collisions

How the formation time effect, jet energy loss and hot wind dissociation affect the

high pT J/psi in the medium:

2-component approach: dissociation + recombinationRAA increases slightly with pT including formation time and B decay X. Zhao, WWND2008; X.Zhao and R. Rapp, hep-ph/07122407

Formation time effect: RAA increases with pT

(formed out of medium) K. Farsch and R. Petronzio, PLB 193(1987), 105 ; J.P. Blaizot and J.Y. Ollitrault, PLB 199(1987),499

Jet energy loss: open charm strongly suppressed observed in the medium

AdS/CFT + Hydro: RAA decreases versus pT

STAR: PRL98(2007) 192301

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Compare to SPS

Similar trend also observed at SPS, might from different physics origin

RHIC: Cu+Cu, , consistent with no suppression at pT > 5 GeV/c

17.3NNs GeV SPS: In+In, , consistent with no suppression at pT > 1.8 GeV/c

200NNs GeV

NA60, QM08

NA50, 158 AGeV

PLB499,85 and NPA774,59

R CP

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J/-h correlation from PYTHIA

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Summary

J/ in p+p and Cu+Cu collisions: pT spectra in p+p: • extended to ~14 GeV/c• follows xT scaling with n=5.6 at pT>5

GeV/c, deviates from scaling at low pT

J/-hadron azimuthal correlation in p+p:• no significant near side correlation

constrain the contribution from BJ/+X

• away-side spectra consistent with h-h correlation gluon or light quark

fragmentation J/ RAA

• indication of RAA increasing at high pT

production mechanisms: • described by NRQCD• soft processes affect low pT

production

• constrain decay contribution• constrain B production and

Be• constrain production

mechanism: CSM or COM

• medium properties

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Single Muon and J/ Efficiency

J/ efficiency

1. muon efficiency at |η|<0.5: 36%, pion efficiency: 0.5-1% at pT>2 GeV/c2. muon-to-pion enhancement factor: 50-1003. muon-to-hadron enhancement factor: 100-1000 including track matching,

tof and dE/dx4. dimuon trigger enhancement factor from online trigger: 10-50 in central

Au+Au collisions

G. Lin, Yale Univ.

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J/ measurements in Heavy Ion Collisions

SPS: Anomalous suppression Significant evidence of deconfinement in central Pb+Pb PLB 477,28 (2000)

NA 50, PLB 477,28 (2000)

RHIC: Similar suppression as SPS, why? Balance of dissociation and regeneration? Other effects