Quarkonia measurements at STAR

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01/23/2009 Lijuan Ruan (heavy flavor workshop, UCLA) 1 Quarkonia measurements at STAR Lijuan Ruan (for the STAR Collaboration) (Brookhaven National Laboratory) Outline: Motivation and introduction J/ψ results Υ results Summary and outlook

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Transcript of Quarkonia measurements at STAR

Quarkonia measurements at STAR Lijuan Ruan (for the STAR Collaboration)
(Brookhaven National Laboratory)
High pT J/ψ in heavy ion collisions
J/ψ H. Satz, Nucl. Phys. A (783):249260(2007)
J/ψ suppression at low pT maybe from excited stats (ψ’, χc) F. Karsch, D. Kharzeev and H. Satz, PLB 637, 75 (2006)
Hot wind dissociation high pT direct J/ψ suppression
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) K. Farsch and R. Petronzio, PLB 193(1987), 105 ; J.P. Blaizot and J.Y. Ollitrault, PLB 199(1987),499
Hot wind dissociation
H. Liu, K. Rajagopal and U.A. Wiedemann PRL 98, 182301(2007) and hep-ph/0607062 M. Chernicoff, J. A. Garcia, A. Guijosa hep-th/0607089
T. Gunji, QM08
Quarkonium production mechanism in p+p
1. Color singlet model (CSM) 1) pQCD 2. Color octet model (COM) 2) NRQCD 3. Color evaporation model (CEM) 3)
4. … Contribution might from: • Gluon fusion • Heavy quark fragmentation 4)
• Gluon fragmentation 5)
• Decay feed-down • … How do we distinguish different production mechanism and different source contribution?
1) R. Baier et al., PLB 102, 364 (1981)
2) M. Kramer, Progress in Particle and Nuclear Physics 47, 141 (2001) 3) H. Fritzsch, PLB 67, 217 (1977)
4) Cong-Feng Qiao, hep-ph/0202227
NRQCD
RPSD
PMD
FPD
FMS
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Low pT J/ψ in p+p and Cu+Cu at 200 GeV J/ψ trigger 0 < pT < 5.5 GeV/c
MC describes position and width
p+p 200 GeV
Cu+Cu 200 GeV
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High pT J/ψ in p+p at 200 GeV J/ψ pT
J/ψ pT
No background at pT>5GeV/c
Reach higher pT (~14GeV/c)
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J/ψ 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
• Consistent with Color Evaporation calculations (R. Vogt, Private communication)
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xT scaling in p+p collisions
n is related to the number of point-like constituents taking an active role in the interaction
n=8: diquark scattering
n=4: QED-like scattering
xT scaling: 1. π and proton at pT>2 GeV/c: n=6.5±0.8 PLB 637, 161(2006) 2. J/ψ at high pT: n=5.6±0.2 J/ψ production: closer to 22 scattering 3. Soft processes affect low pT J/ψ production
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Nuclear modification factor RAA
• Double the pT range to 10GeV/c
• Consistent with no suppression at high pT: RAA(pT>5 GeV/c) = 0.9±0.2
• Indicates RAA increase from low pT to high pT
• Contrast to AdS/CFT prediction
• Formed out of medium? Affect by heavy quark/gluon energy loss
• Decay from other particles?
2-component Approach predicted slightly increase RAA after more consideration X. Zhao, WWND2008
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Disentangle contributions via Correlations
• J/ψ-hadron correlation can also shed light on different source contribution to J/ψ production
• May be used to distinguish CSM and COM
1)
strong near side correlation UA1:PLB 200, 380(1988) and PLB 256,112(1991)
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J/ψ-hadron correlation
STAR Preliminary
J/ψ-hadron correlation in p+p
PRL 95,152301(2005)
h-h correlation • No significant near side J/ψ-hadron azimuthal angle correlation
• Constrain B meson’s contribution to J/ψ yield
• Hints of CSM?
Constrain bottom yields
• pQCD predicts significant BJ/Ψ • correlations shows low B contribution • can used to further constrain B yields
• constrain correlation from jet fragmentation
STAR Preliminary
Yields in near/away side
Associated hadron spectra with leading J/ψ: • 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/ψ not a dominant contributor to inclusive J/ψ constrain J/ψ production mechanism
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J/ψ+ccbar production puzzle
Belle, PRL 89, 142001(2002)
e+e-, 10.6 GeV
0.82 ±0.15 ± 0.14 from new analysis.
While CEM predict 0.049 D. Kang, et al., PRD 71, 094019 and hep-ph/0412381
T. Uglov, EPS 2003
The higher order contribution is significant and can not be neglected.
(e+e- J/ψ +cc)/(e+e- J/ψ + X) = 0.59+0.15 -0.13 ±0.12
NRQCD predict ~0.1 K. Liu and Z. He, PRD 68, 031501 (2003)
B.L. Loffe and D.E. Kharzeev PRD 69, 014016 (2004)
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CSM with kt-factorization
CSM can also describe the data with some improvement like the kt-factorization approach
PHENIX, PRL 92, 05180 (2004)
S.P. Baranov and A. Szczurek arXiv:0710.1792
CSM NLO correction is huge CSM NNLO correction is significant for Υ: Jean-Phillippe Lansberg
dσ /d
PRL98, 252002(2007)
Υ results: p+p and Au+Au at 200 GeV
• Υ (1S+2S+3S) total yield: integrated from 7 to 11 GeV from background-subtracted mee distribution
• Peak width consistent with expected mass resolution • Significance of signal is 3-4σ • Note: Contribution from Drell-Yan (~9%) not subtracted
prelim inary
preliminary
STAR 2006 √s=200 GeV p+p ϒ+ϒ′+ϒ″ →e+e- cross section consistent with pQCD and world data
RAA in progress
Υ results: p+p
Summary
J/ψ 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 J/ψ-hadron azimuthal correlation in p+p: • no significant near side correlation
constrain the contribution from BJ/ψ +X
• away-side spectra consistent with h-h correlation gluon or light quark
fragmentation J/ψ RAA • indication of RAA increasing at high pT
Υ in p+p and Au+Au collisions: • p+p results: consistent with pQCD and world data; RAA in progress
production mechanisms: • described by CEM and CSM • soft processes affect low pT
production
jet contribution (heavy flavor and gluon)
• constrain production mechanism: CSM or COM
• medium properties
ϒ and high-pt J/ψ in run8 dAu
dAu data sampled luminosity: 31 nb-1
STAR Preliminary
STAR Preliminary
STAR Preliminary
STAR Preliminary •J/ψ spectra •J/ψ-h correlation •Isolated J/ψ •ψ(2S) •χc
STAR Preliminary
Future dramatic improvement of J /ψ at low pT
EMC+TOF+HFT (large acceptance): • J/ψ production • Different states predicted to melt at
different T in color medium • Charmonia (J/ψ), bottonia (ϒ)
Quarkonium dissociation temperatures – Digal, Karsch, Satz
pT (e)>1.5 GeV/c
PHENIX Acceptance: |η|<0.35, φ=2*π/2 STAR TOF-Upgrade Acceptance: |η|<0.9, φ=2*π
J/ψ yields from 1 billion minbias Au+Au events: 43.8x10-9/0.040x109*292*0.5*1.8*0.5= 144,0000.3% v2 error σJ/ψ σpp N Nbin ε y RAA
dE/dx after TOF cut
High luminosity for Υ & high-pT J/ψ
RHIC II + DAQ1000: Time-Of-Flight: Electron identification Enhance statistics
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Detector upgrades: HFT and MTD
Heavy Flavor Tracker:
Muon Telescope Detector:
Rejection power: ~16
Muon identification simulation
Backup
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/ψ 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