08/10/2009 Zebo Tang, Weihai 2009 1

J/ production at high transverse momentum

in p+p and A+A collisions

Zebo Tang (USTC)

08/10/2009 Zebo Tang, Weihai 2009 2

Outline

• Introduction– Quark Gluon Plasma (QGP) – J/ as a probe of QGP– J/ production mechanism in p+p collisions

• High pT J/ reconstruction– Electron identification– High pT J/e+e- reconstruction

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

• Summary and outlook

08/10/2009 Zebo Tang, Weihai 2009 3

Quark-Hadron phase transition

Net Baryon Density

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Relativistic Heavy Ion Collider (RHIC)

Animation M. Lisa

RHIC BRAHMSPHOBOS

PHENIXSTAR

AGS

TANDEMS

v = 0.99995c = 186,000 miles/sec Au + Au at 200 GeV

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J/ melting in QGP

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

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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? Or sequential suppression?

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Sequential suppression

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

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

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Sur

viva

l pos

sibi

lity

pT

Direct J/ suppression

J/

H. Liu, K. Rajagopal and U.A. WiedemannPRL 98, 182301(2007) and hep-ph/0607062M. Chernicoff, J. A. Garcia, A. Guijosa hep-th/0607089

T. Gunji, QM08

Can we observed direct J/ suppression?

Hot wind dissociation high pT direct J/ suppression

Hot wind dissociationAdS/CFT calculation

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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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Disentangle contributions via Correlations

• J/-hadron correlation can also shed light on different source contribution to J/ production

• CSM vs. COM

1)

no near side correlation

2)

strong near side correlation

g g g /J

g g b b hadron

B X /J X

PLB 200, 380(1988) and PLB 256,112(1991)

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The STAR Detector

MRPC ToF barrelMRPC ToF barrel75% for run 975% for run 9

RPSD

PMD

FPD

FMS

EMC barrel

EMC End Cap

DAQ1000DAQ1000

Take data FGT

Complete

Ongoing

MTD (BNL LDRD)

R&DHFT: R&D

TPC

TPC+EMC for this analysis

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Electron identification (TPC only)

With TPC only:• no electron ID at low pT

• difficult 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 deposited energy:Further suppress high pT hadrons

x0.05x0.05)

~5X0

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Electron ID (SMD)

electron hadron

Shower Maximum Detector:• shower size• shower position

Further suppress hadron contamination

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High pT J/ e+ e- reconstruction technique

PYTHIA decay

p+p run6

Trigger efficiencyTracking efficiency

acceptance

High pT electron

High pT J/ high pT electron (TPC+EMC) lower pT electron (TPC only)

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High pT J/ in p+p at 200 GeVJ/ pT

J/ pT

EMC+TPC electrons:1, pT>2.5 GeV/c

TPC only electrons:1, pT>1.2 GeV/c

EMC+TPC electrons:1, pT>4.0 GeV/c

TPC only electrons:1, pT>1.2 GeV/c

No background at pT>5 GeV/c

Reach higher pT (~14 GeV/c)

p+p 2005

p+p 2006

STAR Preliminary

EMC (High Tower) trigger:5 < pT < 14 GeV/c

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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

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Compare to pQCD and NRQCD

Model comparisons:

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 contribution. G. C. Nayak, M. X. Liu, and F. Cooper, Phys. Rev. D68, 034003 (2003), and private communication.

CS and LO CS+CO have different power parameters different diagram contribution?

power parameter: n=8 for NNLO CS n=6 for LO CS+CO

STAR Preliminary

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xT scaling in p+p collisions

n is related to thenumber of point-likeconstituents takingan active role in theinteraction

n=8: diquark scattering

n=4: QED-like scattering

pT>2 GeV/c

STAR Preliminary

pT>5 GeV/c

and proton at pT>2 GeV/c: n=6.6±0.1 (PLB 637, 161(2006))

J/ at high pT: n=5.6±0.2 (close to CS+CO prediction)

Soft processes affect low pT J/ production

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Nuclear modification factor RAA

• Consistent with no suppression at high pT: RAA(pT>5 GeV/c) = 1.4± 0.4±0.2

• All RHIC measurements: RAA = 1.1 ± 0.3 ± 0.2

• Indicates RAA increase from low pT to high pT

STAR Preliminary

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Nuclear modification factor RAA

• Consistent with no suppression at high pT: RAA(pT>5 GeV/c) = 1.4± 0.4±0.2

• All RHIC measurements:

RAA(pT>5 GeV/c) = 1.1 ± 0.3 ± 0.2

• Indicates RAA increase from low pT to high pT

• Contrast to AdS/CFT+ Hydro prediction H. Liu, K. Rajagopal and U.A. Wiedemann PRL 98, 182301(2007), T. Gunji, JPG 35, 104137(2008) • How does production mechanism (CS vs. CO) affect energy loss?• Good jobs:

• transport+hydro: from initial produced instead of regenerated Y.Liu, Zhen Qu, N. Xu and P. Zhuang, arXiv:0901.2757; N. Xu, QM2009 • two-component model: leakage and B feeddown is important R. Rapp, X. Zhao, arXiv:0806.1239

STAR Preliminary

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Disentangle contributions via Correlations

• J/-hadron correlation can also shed light on different source contribution to J/ production

• CSM vs. COM

1)

no near side correlation

2)

strong near side correlation

g g g /J

g g b b hadron

B X /J X

PLB 200, 380(1988) and PLB 256,112(1991)

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J/-hadron correlation

(S+B)/B: 54/14

5.4

Heavy quark fragmentation

Near side correlation

Good S/B ratio makes this measurement possible

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J/hadron correlation in p+p

PRL 95,152301(2005)

h-h correlation• No significant near side J/-hadron azimuthal angle correlation

• Constrain B meson’s contribution to J/ yield

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Constrain bottom yields

• Correlations shows low B contribution (13 5) %• Can used to further constrain B yields

STAR Preliminary

STAR Preliminary

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Constrain bottom yields

• pQCD predicts significant BJ/ • Correlations shows low B contribution• Can used to further constrain B yields• Constrain Be

M. Cacciari, P. Nason and R. Vogt RL 95(2005),122001; CLEO collaboration PRL 89(2002),282001

STAR Preliminary

STAR Preliminary

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Yields in near/away side

Associated hadron spectra with leading J/: • Away side: Consistent with leading charged hadron correlation measurement (h-h) away-side from gluon or light quark fragmentation • Near side: Consistent with no associated hadron production BJ/ not a dominant contributor to inclusive J/ constrain J/ production mechanism

STAR Preliminary

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High-pT J/ in run8 d+Au

dAu EMC data sampled luminosity: 31 nb-1

p+p equivalent: 13 pb-1

•J/ spectra •(2S)•c

•J/-hadron correlation•Isolated J/•J/ in Jet

Reduced material budget by a factor of ~10

Efficiency under going

420 signals13

New 500 GeV p+p data is coming!Also 200 GeV p+p with higher lum.200 GeV Au+Au and Energy scan.

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Summary

J/ spectra in 200 GeV p+p collisions at STAR Significantly extend previous measurement from 5 GeV/c to ~14 GeV/c, provide powerful tool to constrain model calculations High pT J/ follows xT scaling with n=5.6, consistent with COM slope Low pT J/ deviates from xT scaling suggests soft process can affect low pT J/ production.

J/ spectra in 200 GeV Cu+Cu collisions

First observation of no suppression for hadron at high pT at STAR Indication of RAA increasing from low pT to high pT

Jhadron azimuthal correlation in p+p First quarknonium-hadron correlation measurement at RHIC No significant near side correlation BJ/ contribution = 135% Can be used to constrain B production, and help to separate be from ce

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Extra slides

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What I am going to try (low pT)

500 GeV p+p, 2009, preliminary calibration

TPC+TOF

Low pT J/ee:• Total cross section• <pT

2>

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What I am going to try (other charmonia)

TOF: /K upto 1.6 GeV/c, p/(,K) upto 3 GeV/c

With extended PID from TOF and high luminosity of RHICII:The reconstruction of the other charmonium states through their hadronic channels are possible and worth to try

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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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MRPC ToF barrelMRPC ToF barrelReady for run 10Ready for run 10

RPSD

PMD

FPD

FMS

EMC barrel

EMC End Cap

DAQ1000DAQ1000Ready for run 9 FGT

Complete

Ongoing

MTD (BNL LDRD)

R&DHFT

TPC

The STAR Detector

Run8: without any inner tracker

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Jpsi-h correlation from PYTHIA

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High pT J/ in heavy ion collisions (Cont.)

2-component approach: dissociation + recombination

RAA decreases slightly or flat with pT X. Zhao and R. Rapp, hep-ph/07122407

RAA increase slightly with pT including formation time and B decay X. Zhao, WWND2008

Color singlet model:

RAA increase with pT (formed out of medium) F. Karsch and R. Petronzio, PLB 193(1987), 105 ;

J.P. Blaizot and J.Y. Ollitrault, PLB 199(1987),499

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Datasets

p+p data sample: 1. EMC triggered events in year 2005 ET>3.5 GeV Integrated luminosity: 3 (pb)-1

2. EMC triggered events in year 2006 ET>5.4 GeV Integrated luminosity: 11 (pb)-1

Cu+Cu data sample: 1. EMC triggered events in year 2005 ET>3.75 GeV Integrated luminosity: 0.9 (nb)-1

pp-equivalent: 3 (pb)-1

High-pT J/p+p data sample:• 1. J/ψ triggered events in year 2006

• Integrated luminosity: 377 (nb)-1

• 2. Υ triggered events in year 2006

• Integrated luminosity: 9(pb)-1

Au+Au data sample:• 1. Υ triggered events in year 2007

Integrated luminosity: 300(μb)-1

pp-equivalent: 12(pb)-1

Triggered data

Lectures on Physics of High-Energy Nuclear Collisions

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Heavy Quark Potential

rr

TrV

25.0),(

Cornell-potential:

At zero temperature, V(r,0) r, Confinement ! At high temperature, the confinement potential ‘melted’ De-confinement ! J/ suppression ! T.Matsui and H.Satz, Phys. Lett. B178, 416(1986)

F. Karsch, E. Laermann, A. Peikert, Nucl. Phys. B605, 579(2001)

Nu Xu, Lecture at USTC, Oct. 2006

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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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Sequential suppression

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

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

?

Plasma thermometer