Quarkonia in STAR

1
Quarkonia in STAR

• Results and Future Plans

Winter Workshop on Nuclear Dynamics Ocho Rios,
Jamaica January 3, 2010.
2
Outline

• J/y production from low to high-p?.
• pp Understanding quarkonium production
  mechanisms
• Longstanding issue.
• J/y Azimuthal correlations, a way to gain
  insight.
• AA RAA at low and high p?.
• Signals in Runs 8 and 9 (Low material).
• ? production.
• pp cross section.
• Baseline for dAu and AuAu comparison.
• dAu and AuAu, towards cold and hot nuclear
  matter effects
• Future detectors for Quarkonia MTD.
• Conclusions

3
J/y in pp collisions

• Baseline for AA
• Production mechanism
• Color singlet model (CSM)
• underpredicted CDF data by order of magnitude
• Color octet model (COM)
• good agreement with CDF cross section
• disagreement with CDF polarization
• Feeddown
• B?J/y through J/y-hadron correlation

1.8 TeV
4
J/y spectra in pp and CuCu at 200 GeV
STAR Collaboration Phys.Rev.C80041902,2009
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 CSCO have different power parameters
  different diagram contribution?
• power parameter
• n8 for NNLO CS
• n6 for LO CSCO

5
J/y-h azimuthal correlation

• Correlations show low B contribution (13 5)
• Can be used to further constrain B yields

• Production mechanisms in pp
• CS model cg fusion important.
• J/yc 10-45 of all J/y.
• Future study via J/yD or J/ye
• S. Brodsky, J.-P. Lansberg, arXiv0908.0754

6
Low-pT J/y in dAu, Run 8

• Signal, all centralities.

Like-sign subtracted
RdAu consistent with Nbin scaling
Corrected, 0-20 most central
7
J/? p? spectrum

• STAR ability to measure J/?
• from low- to high-pT
• PHENIX better precision
• STAR wider rapidity coverage

AuAu 200 GeV Run 7
STAR Preliminary
STAR Preliminary
STAR high-pT J/? arXiv0904.0439 STAR CuCu
arXiv0907.4458v2 STAR pp arXiv0806.0347v1 PHEN
IX CuCu Phys. Rev. Lett. 101, 122301
(2008) PHENIX p Phys. Rev. Lett. 98, 232002
(2007) PHENIX AuAu, Phys. Rev. Lett. 98, 232301
(2007)
8
AuAu RHIC Run 7 - RAA

• AuAu run 7 STAR Low p? J/y in heavy-ions.

0-20
0-20
20-80
20-80
STAR Preliminary
STAR Preliminary
STAR Preliminary
STAR Preliminary

• Agreement between STAR and PHENIX.
• Model color screening in QGP, dissociation in
  hadronic phase, statistical recombination, B ?
  J/? feed-down and formation time effects

PHENIX Phys. Rev. Lett. 98, 232301 (2007)
9
RAA at high-p?

• Consistent with no suppression at high p?
• RAA(p?gt5 GeV/c) 1.4 0.40.2
• RAA(p?gt5 GeV/c) gt 0.6 (97 C.L.)
• RAA increase from low p? to high p?

• Jet quenching strong open charm suppression.
  (NPE results)
• Production of J/y through CS states likely
• 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.
• Contrast to 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 feeddown reproduces the trend
• X. Zhao and R. Rapp (2007), arXiv0712.2407 Y.P.
  Liu, et al., Phys.Lett.B67872-76,2009

10
Runs 8 and 9 Reduced Material

• Run 8 dAu, high p?

13 s signal

• Run 8 pp

• Run 9, High-Level Trigger

11
Bottomonia A cleaner probe

• Sequential disappearance of states
• Color screening ? Deconfinement
• Matsui T and Satz H 1986 Phys.Lett.B178416,1986
• QCD thermometer ? QGP Properties
• A. Mocsy and P. Petraczky PRD 77 014501 (2008)

A .Mocsy, 417th WE-Heraeus-Seminar,2008
Expectation at 200 GeV ?(1S) does not melt ?(2S)
is likely to melt ?(3S) will melt
12
? Pros and Cons

• Pros
• Efficient trigger - works in pp up to central
  AA
• Large acceptance at ylt0.5
• Small background at M10 GeV/c2
• Co-mover absorption is very small
• Recombination negligible at RHIC (?bb ltlt ?cc)
• Cons
• extremely low rate
• 10-9/minimum bias pp interaction
• Good resolution needed to separate 3 S-states

Z.W. Lin and C.M Ko PLB 503104 (2001)
13
First Analysis ? in pp (2006)
QM 2006
J. Phys. G Nucl. Part. Phys. 34(2007)S947
14
STAR ? vs. theory and world data
J. Phys. G Nucl. Part. Phys. 34(2007)S947
STAR 2006 vs200 GeV pp ??????ee- cross
section consistent with pQCD and world data trend
15
Improvements to pp 2006 ? analysis

• Included all available statistics
• Track to cluster matching
• Removes random benefit
• Isolation cut
• Removes additional jet background
• Estimate contribution from Drell-Yan and bb
  continuum
• Results are statistically consistent with QM 2006
  result

16
contribution from PYTHIA 8 Drell-Yan
ylt0.5 8ltmlt11
1S Efficiency
1S Efficiency
From simulated bb and Drell-Yan curves we obtain
an expected shape in STAR
Private communication R. Vogt
bb and Drell-Yan cross-sections determined by a
combined fit to background subtracted data
17
? in AuAu at vs 200 GeV
QM 2008
RAAlt 1.3 at 90 CL
Used QM 2006 pp analysis cuts
S/B can be improved
Inclusion of pp analysis improvements in progress
J. Phys. G Nucl. Part. Phys. 35(2008)104153
18
? in dAu
QM 2009
arXiv0907.4538

• Signal Background ? unlike-sign electron pairs
• Background ? like-sign electron pairs
• ?(1S2S3S) total yield integrated from 7 to 11
  GeV from background-subtracted mee distribution
• Raw Yield 172 /- 20 (stat.)
• Strong signal (8s significance)

19
Nuclear modification factor
spp 42 mb
sdAu 2.2 b
arXiv0907.4538
Nbin 7.5 0.4 for Minbias dAu
Consistent with Nbin scaling Cold Nuclear Matter
effects (Shadowing) are not large.
J. Phys. G Nucl. Part. Phys. 34(2007)S947
20
Future MTD for Heavy Quarkonia

• Muon Telescope Detector
• Based on MRPC technology.
• Covering the magnet iron bars (gaps in-between
  uncovered).
• Acceptance 56.6 at ?lt0.8
• muon efficiency 45, pion efficiency 0.5-1 at
  pTgt2 GeV/c
• muon-to-pion enhancement factor 50-100
• muon-to-hadron enhancement 100-1000 (track
  matching, TOF and dE/dx)
• dimuon trigger enhancement factor from online
  trigger 10-50

?Together with DAQ1000 greatly enhance STARs
capability of Quarkonia and dilepton program in
RHIC II and future QCD Lab
21
Conclusions and Outlook

• J/y spectra in 200 GeV pp collisions at STAR
• Extend the pT range up to 14 GeV/c
• Spectra can be described by CEM and CSM.
• High pT J/y follows xT scaling with n5.6
• J/y-hadron azimuthal correlation in pp
• No significant near side correlation
• Expect strong near-side correlation from B ?J/yX
• Constrain J/y production mechanism
• J/y RAA from CuCu collisions
• Extend RAA from pT 5 GeV/c to 10 GeV/c
• Indication of RAA increasing at high pT

• ??????ee- cross-section at vs200 GeV
• pp
• B(ds/dy) 9128(stat)22(sys) pb
• dAu
• B(ds/dy) 354(stat)5(sys) nb and
• RdAu 0.980.32(stat)0.28(sys)
• Consistent with Binary Scaling
• Good reference for QGP effects
• AuAu (central 0-60) - 4s Signal significance
• RAAlt 1.3 at 90 CL

22
Outlook

• New 500 GeV pp data coming.
• 200 GeV dAu run 8
• J/y-hadron correlation
• Isolated J/?
• J/? in Jet
• 200 GeV pp run 9
• higher luminosity
• low material
• J/? spectra
• ?(2S)
• ?c maybe?
• ? measurement from 20 pb-1(8 pb-1 in run 6 pp)
• May allow separation of 1S, 2S, 3S states
• MTD additional quarkonia capabilities.
• dimuon Trigger enhancement factor 10-50

23
Backup
24
? Cross section in d-Au at STAR
N? 172 20
?? 0.15 0.02
?Ldt 32 nb-1
dy 1.0
arXiv0907.4538
25
CuCu - RAA vs. centrality
95 C.L. Limit
STAR Preliminary
PHENIX Phys. Rev. Lett. 101, 122301 (2008)
bars - stat. errors brackets syst. errors
Modest statistics ? limited discrimination power
26
xT scaling in pp collisions

• xT scaling
• 1. p and proton at pTgt2 GeV/c n6.60.1 PLB 637,
  161(2006)
• 2. J/y at high pT n5.60.2
• (power parameter close to CSCO prediction)
• 3. Soft processes affect low pT J/y production