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Zhangbu XuBrookhaven National Laboratory

Quarkonium measurements with STAR

Outline:• High-pT J/y results• J/y spectrum and flow• J/y-h correlations• The story of B and J/y decay feed-down

• Outlook

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High pT J/y in heavy ion collisions

J/yH. Satz, Nucl. Phys. A (783):249-260(2007)

J/y suppression at low pT could befrom suppressed excited states (y’, cc)F. Karsch, D. Kharzeev and H. Satz, PLB 637, 75 (2006)

High pT direct J/y suppression related to hot wind dissociation?

Hot wind dissociation

H. Liu, K. Rajagopal and U.A. WiedemannPRL 98, 182301(2007) and hep-ph/0607062

2-component approachPredicted increase RAA X. Zhao and R. Rapp, hep-ph/07122407Y.P. Liu, et al., Phys.Lett.B678:72-76,2009

Color singlet model predicted an increase RAA

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

T. Gunji, QM08

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Quarkonia in QGP

• Color screening effect 1)

• Recombination 2)

• Gluon energy loss 3)

• Heavy quark energy loss 3)

• Decay feed-down• (comover, cold matter effect) at (hadronic phase, initial stage)• Can we use effects in HI to figure out the J/ production and

medium properties?

1) T. Matsui and H. Satz, Phys. Lett. B178, 416 (1986)2) R. L. Thews and M. L. Mangano, Phys. Rev. C73, 014904 (2006)3) M. B. Johnson et al., Phys. Rev. Lett. 86, 4483 (2001) and R. Baier et al., Ann. Rev. Nucl. Part. Sci. 50, 37 (2000)

How do the quarkonia behave in the presence of sQGP?

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High pT J/y in p+p at 200 GeV

J/y pT

J/y pT

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

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

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

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

No background at pT>5GeV/c

Reach higher pT (~14GeV/c)

p+p 2005

p+p 2006

(S+B)/B: 24/2

(S+B)/B: 54/14

EMC trigger

3 pb-1

11 pb-1

Need to see good signal before taking next step!

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

Model comparisons:

Color singlet model (CS): 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+ color octet (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 Collaboration, Phys. Rev. C 80 (2009) 41902

Statistics: red curve is NOT a fit, 4th data point too low?

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xT scaling in p+p collisions

arXiv: 0904.0439

xT scaling: 1. and proton at pT>2 GeV/c: n=6.6±0.1 PLB 637, 161(2006)2. J/y at high pT: n=5.6±0.2 (the power parameter close to

CS+CO prediction)3. Soft processes affect low pT J/y 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

• RAA(pT>5GeV/c) > 0.6 (97% C.L.) RAA increase from low pT to high pT

• Jet quenching: strong open charm suppression. 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.

• Different from AdS/CFT+ Hydro prediction (99% C.L.) H. Liu, K. Rajagopal and U.A. Wiedemann PRL 98, 182301(2007);T. Gunji, J. Phys.G 35, 104137 (2008)

• Formation time, gluon dissociation, recombination, B reproduces the trend X. Zhao and R. Rapp (2007), arXiv:0712.2407; Y.P. Liu, et al., Phys.Lett.B678:72-76,2009

arXiv: 0904.0439

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J/y flow and thermalization

• There are quite reasonable evidences: J/y suppression open charm recombination (yields, rapidity, centrality)

• Elliptic flow has not been measured• Spectrum must reflect radial flow and degree

of thermalization• To compare the results among pp, peripheral

AA and central AA, using non-extensive statistics

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Tsallis statistics describes hadron spectra

)1/(1)11( --- q

TmT

q

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No flow pattern in J/y spectra

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No sign of flow at SPS either

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J/y flow and thermalization• Spectrum must reflect

radial flow and degree of thermalization: – no signal of radial flow– Non-extensive Blast-wave

is wrong (likely)?but RAA is relatively flat at low pT

– Cancellation from recombination, flow and suppression (3 = zero)?

– Suppression only of the excited states?– What is elliptic flow for J/y? And the

arguments are?

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What should RAA be?

There are only couple of (non-over-reaching) choices: both have significant impact on our understanding of J/ and medium propertiesup: recombination/flow, formation timedown: energy loss, AdS/CFTSo far, more indication of up than downCu, In system too small?Data in tape from RHIC run10 Au+Au will tell!

R. Arnaldi (NA60) QM08

J/y-hadron correlation

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Heavy quark fragmentation

Near side correlationBottom decay or fragmentation

Good S/B ratio makes this measurement possible

S.J. Brodsky, J.-P. Landberg, arXiv: 0908.0754TPC FMS

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Disentangle contributions via Correlations

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

• May be used to distinct bottom decay, charm associate production

1)

no near side correlation

2)

strong near side correlation

g g gc /J y

g g b b hadron

B X /J Xy

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

Yields in near/away side

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Associated hadron spectra with leading J/y: • 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/y not a dominant contributor to inclusive J/y constrain J/y production mechanism

Zebo Tang Thesis 2009

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J/ Constrain bottom yields

• correlations shows B contribution (13 5) %• can be used to further constrain B yields• Bottom decay kinematics, less production

origin

STAR Preliminary

arXiv: 0904.0439

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Constrain bottom yields

• pQCD predicts significant BJ/y

• can be used to further constrain B yields

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

STAR Preliminary

arXiv: 0904.0439 arXiv: 0904.0439

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BJ/ is a golden channel

Xin Dong

Much better kinematic correlationNo mixing of D+BNo direct J/ decay feed-downExperimentally clean measurement

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HFT upgrade

STAR HFT proposal, Wei Xie et al.

BX+J/+- simulation in progress

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Future dramatic improvement of J /y at low pT

pT (e)>1.5 GeV/c

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

J/y yields from 300M minbias Au+Au events: 43.8x10-9/0.040x3x108*292*0.5*1.8*0.5= 40,0000.6% v2 errorsJ/y spp N Nbin e y RAA

dE/dx after TOF cut

0-20% d+Au

significance ~ 5.7 σ

Joint CATHIE-TECHQM, BNL, 12/14/09

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High luminosity for Υ & J/ySTAR EMC

simulation

L.Ruan et al., 0904.3774, JPG36(2009); Z. Xu, BNL LDRD project 07-007STAR Muon Telescope Detector

MTD: excellent mass resolution for Υ separate different Υ states

Muon Telescope Detector

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L.Ruan et al., 0904.3774, JPG36(2009)

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Summary (J/y)• J/y spectra in 200 GeV p+p collisions at STAR

1. Extend the pT range up to ~14 GeV/c 2. Spectra can be described by CEM and CSM. 3. High pT J/y follows xT scaling with n=5.64. Spectra at high pT can be used to constrain B production

• J/y-hadron azimuthal correlation in p+p

1. no significant near side correlation Expect strong near-side correlation from BJ/y+X Can be used to constrain J/y production mechanism

2. Away-side spectra consistent with h-h correlation indicates gluon or light quark fragmentation

• J/y RAA from 200 GeV Cu+Cu collisions at STAR1. Extend RAA from pT = 5 GeV/c to 10 GeV/c2. Indication of RAA increasing at high pT

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Future

Upsilon RAA

Au+Au and p+p runs with TOF and DAQ1000

J/ elliptic flow

Upsilon states (1S+2S+3S, MTD)

J/ displace vertex (HFT+MTD)

26arXiv:1005:1627