1 zhangbu xu (for the star collaboration) brookhaven national laboratory high-p t j/ at star...
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1
Zhangbu Xu (for the STAR Collaboration)
Brookhaven National Laboratory
High-pT J/atSTAR
Outline:
• Introduction
• J/ yields and suppression
• J/-h correlation
• Outlook (+MTD)
Quarkonia in sQGP
• 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)
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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 quarkonium behave in the presence of sQGP?
High pT J/ in heavy ion collisions
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J/H. Satz, Nucl. Phys. A (783):249-260(2007)
J/ suppression at low pT could befrom suppressed excited states (’, c)F. Karsch, D. Kharzeev and H. Satz, PLB 637, 75 (2006)
High pT direct J/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 decrease RAA
X. Zhao and R. Rapp, hep-ph/07122407
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
The STAR Detector
Zebo Tang, USTC/BNL 4
MagnetMagnet
CoilsCoils
Central Central TriggerTriggerBarrel Barrel (CTB)(CTB)
ZCalZCal
Time Time Projection Projection
ChamberChamber(TPC)(TPC)
Year 2000Year 2000
Barrel EM Cal Barrel EM Cal (BEMC)(BEMC)
Silicon Vertex Silicon Vertex Tracker (SVT)Tracker (SVT)Silicon Strip Silicon Strip Detector (SSD)Detector (SSD)
FTPCFTPCEndcap EM CalEndcap EM CalFPDFPD
TOFp, TOFrTOFp, TOFr
PMDPMD
Year 2001+Year 2001+
Large acceptance: 2 coverage at mid-rapidity
Future upgrade: Time of Flight, DAQ1000, Heavy Flavor Tracker, Muon Telescope DetectorFuture upgrade: Time of Flight, DAQ1000, Heavy Flavor Tracker, Muon Telescope Detector
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Low pT J/ in p+p at 200 GeV
J/ trigger 0 < pT < 5.5 GeV/c
MC describes position and width
p+p 200 GeV
STAR has J/ capabilities at low pT
Mass and width consistent with MC simulation, low mass tail from electron bremsstrahlung
Integrated p+p luminosity at 200 GeV: 0.4 (pb)-1
High pT J/ in p+p at 200 GeV
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J/ 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>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
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J/ spectra in p+p 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)
Nuclear modification factor RAA
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• Double the pT range to 10GeV/c
• Consistent with no suppression at high pT:
RAA(pT>5 GeV/c) = 0.9±0.2 2 above low-pT data
• Indicates RAA increase from low pT to high pT
• Doesn’t agree with 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
RAA Comparison to NA60
200NNs GeV
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RHIC: Cu+Cu, consistent with no suppression at pT > 5 GeV
17.3NNs GeV SPS: In+In, , consistent with no suppression at pT > 1.8 GeV
CroninpAppThermal fit
R. Arnaldi (NA60) QM08
Important to understand production mechanism
Quarkonium production mechanism Color singlet model (CSM) 1) pQCD Color octet model (COM) 2) NRQCD Color evaporation model (CEM) 3)
…
• Gluon fusion
• Heavy quark fragmentation 4)
• Gluon fragmentation 5)
• Decay feed-down
• …
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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/02022275) K. Hagiwara et al., hep-ph/0705.0803
NRQCD
What’s the production mechanism at RHIC energy?
CSM with kt-factorization
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CSM can also describe the data with some improvement likethe kt-factorization approach
PHENIX, PRL 92, 05180 (2004)
S.P. Baranov and A. SzczurekarXiv:0710.1792
d/d
pT [
nb/(
GeV
/c)]
p T (GeV/c)
Color singletLHC 14 TeV
Tevatron 1.96 TeV LO NLO
PRL98, 252002(2007)
xT scaling
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n is related to thenumber of point-likeconstituents taking anactive role in theinteraction
n=8: diquark scatteringn=4: QED-like
scattering
xT scaling: and proton: n=6.5±0.8 PLB 637, 161(2006) J/: n=5.6±0.2 J/ production: closer to 22 scattering
(B J/)/(inclusive J/)
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1) Generated B spectrum is from pQCD
M. Cacciari, P. Nason and R. Vogt
PRL 95(2005),122001
2) Decay BJ/, kinematics and branch ratio are from CLEO measurements
CLEO collaboration
PRL 89(2002),282001
• BJ/ contributes significantly to the inclusive J/ yields at high pT (>5 GeV/c) Assuming B production from pQCD (no experimental B spectra at RHIC yet)• Can be used to constrain B production
More J/ production puzzles
c
0D
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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
What happens?: In p+p collisions;At higher energy (200 GeV)
(e+e- J/ +cc)/(e+e- J/ + 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. KharzeevPRD 69, 014016 (2004)
0c(2 )c S *D
c
J/-hadron correlation
RBRC Workshop, BNL, April 23-25, 2008
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(S+B)/B: 54/14Heavy quark fragmentation
Near side correlation
Good S/B ratio makes this measurement possible
Disentangle contributions via Correlations
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• J/-hadron correlation can also shed light on different source contribution to J/ production
• May be used to distinct CSM and 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)
J/hadron correlation in p+p
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PRL 95,152301(2005)
h-h correlation• No significant near side J/-hadron azimuthal angle correlation
• Constrain B meson’s contribution to J/ yield
• Hints of CSM?
Yields in near/away side
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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
Constrain Bottom yields
• pQCD predicts significant BJ/ • Correlations shows low B contribution• can used to further constrain B yields• PYTHIA productions all show strong near-side correlation higher order production mechanism?
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Future dramatic improvement of J / at low pT
EMC+TOF (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 109 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
High luminosity for Υ & high-pT J/
RHIC II + DAQ1000:Time-Of-Flight:
Electron identification Enhance statistics
Longer term: Quarkonia in STARHeavy Flavor Tracker:
Muon Telescope Detector:
e+e- rejection
Topologically reconstructJ/ from B decay
Rejection power: ~16
+-
simulationMuon identification
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A novel and compact muon telescope detector for QCDLab
A large area of muon telescope detector (MTD) at mid-rapidity, allows for the detection of
• di-muon pairs from QGP thermal radiation, quarkonia, light vector mesons, possible correlations of quarks and gluons as resonances in QGP, and Drell-Yan production • single muons from their semi- leptonic decays of heavy flavor hadrons• advantages over electrons: no conversion, much less Dalitz decay contribution, less affected by radiative losses in the detector materials
+-
BNL LDRD 07—007 project
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Concept of Design
A pseudo detector with scintillator covering the whole iron bars and left the gaps in-between uncovered.
1. muon efficiency: 35-45%, pion efficiency: 0.5-1%2. 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
Detection efficiency
pT (GeV)
pionmuon
This together with DAQ1000 will greatly enhance our capability of J/ and other dilepton program in RHIC II and future QCD Lab
Cosmic Ray Results: Long-Strip Multi-gap Resistive Plate Chamber Technology
Long MRPC Technology with double-end readout
HV: 6.3 KV
gas mixture: 95% Freon + 5% isobutane
time resolution: ~60 ps
spatial resolution: ~1cm
efficiency: >95%
950 mm
25
6
mm
25
m
m
Y. Sun et al., nucl-ex/0805.2459
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HV: 6.3 KVgas mixture: 95% Freon + 5%
isobutanetime resolution: ~60-70 ps
spatial resolution: ~0.6-1cmefficiency: >95%
consistent with cosmic test results
Tsinghua module as
trigger
Scintillator as trigger
USTCY. Sun et al., nucl-ex/0805.2459
Fermi Lab Beam Test Results (T963 May 2-15 2007)
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STAR-MTD in Year 2007
• iron bars as hadron absorber; two scintillator trays as our trigger
• 403 cm away from TPC center, ||<0.25
• gas: 95% Freon and 5% iso-butane; HV: 6.3 KV
• MTD Triggered events: 380 K Au+Au events were taken 1.7 M d+Au and 700 K p+p events taken in run 8
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Performance at STAR
• MTD hits: matched with real high pT tracks
• z distribution has two components: narrow (muon) and broad (hadron) ones
• spatial resolution (narrow Gaussian) is ~10 cm at pT>2 GeV; hadron rejection: 200-300
• time resolution: 300 ps Improve our electronics with full scale detector
STAR Preliminary
pT>2 GeV/c
STAR Preliminary
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Compared to Simulation
from data: pT>2 GeV/c, (z) of muon: ~10 cm
from simulation: pT=2.5 GeV/c, (z) of muon: ~9 cm
Data and simulation show consistent results
pT (
GeV
/c)
z (cm)
muons pions muons
Are they prompt muons?
MTD hit distribution
dE/dx (
Time of flight ()
Ks-
Kaon dE/dx
n<-1 n>0
n>0pT>2 GeV/c
STAR Preliminary
pT>2 GeV/c
Nu XuRHIC Science and Technology
Review, July 7-9, 200832/30
A complete MTD at STAR
MRPC ToF MRPC ToF barrelbarrelReady for run 10Ready for run 10
RPSD
PMD
FPD
FMS
EMC barrel
EMC End Cap
DAQ1000DAQ1000Ready for run 9 FGT
Complete
Ongoing
MTD
R&DHFT
TPC
• To install another tray with TOF electronics in run9• Collaborators for a proposal of full scale detector:
56.6% in azimuth, |eta|<0.88; current tray design: 360 modules, 2160 read-out strips, 4320 channels. (TOF: 23 K readout channels).
Summary (J/)
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• J/ spectra in 200 GeV p+p collisions at STAR1. Extend the pT range up to ~14 GeV/c 2. Spectra can be described by CEM and CSM. 3. High pT J/ follows xT scaling with n=5.64. Spectra at high pT can be used to constrain B production
• Jhadron azimuthal correlation in p+p
1. no significant near side correlation Expect strong near-side correlation from BJ/+X Can be used to constrain J/ production mechanism
2. Away-side spectra consistent with h-h correlation indicates gluon or light quark fragmentation
• J/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
Future
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J/ results from Run 7 Au+Au, data is still under production
Upsilon RAA
Run 8 (d+Au) just finished, Cold Nuclear Modification
Run9—10, Au+Au and p+p runs with TOF and DAQ1000
Longer term: HFT, MTD
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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
06/17/2008 Lijuan Ruan (UC Davis Collboration Meeting) 37
Muon Identification: dE/dx Effect
STAR Preliminary
n<-1
STAR Preliminary
n>0
• the narrow Gaussian distribution: dominated by muons
STAR Preliminary STAR Preliminary
|z|<20
06/17/2008Lijuan Ruan (UC Davis Collboration
Meeting)38
How do I know dE/dx is right?
dE/dx: by selecting pions from KS daughternsigmapion for pion: -1.16 (mean), 1.14 (sigma)
06/17/2008 Lijuan Ruan (UC Davis Collboration Meeting) 39
• the narrow Gaussian distribution: dominated by muons
Muon Identification: Cut on High Velocity STAR Preliminary
STAR Preliminary
STAR Preliminary
STAR Preliminary
1/trackhits- 1/rawhits >0
n>0
STAR Preliminary
06/17/2008Lijuan Ruan (UC Davis Collboration
Meeting)40
Muons from Pion Decay?
Primary tracksOther sector: 4.65e05 pT> 2 GeV/c tracks, 2236 KS reconstructed.
MTD matched tracks: 2619 tracks, 3.35.8 KS obsverd. If all muons are from pion decay, 13 KS expected.
Consistent with no secondary muon contribution to narrow Gaussian from pion decay.
06/17/2008Lijuan Ruan (UC Davis Collboration
Meeting)41
Muons from Kaon Decay?
Left plot: no dE/dx cut Right plot: -5<n<-2.6, Pion(-1.2) Muon(-0.6) Kaon(-2.6), then Muon: 4.8%,Kaon: 48%. I observed 99-1624*4.8%=22 muons.
Muons from kaon decay: 22/48%/1624=2.8%.
Secondary muons contribution to narrow Gaussian is small from kaon decay.
pT>2 GeV/c
STAR Preliminary