STAR Heavy Ion Recent Highlights and Results

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STAR Heavy Ion Recent Highlights and Results
Xin Dong Lawrence Berkeley National Lab for the
STAR Collaboration
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Where are we
Goal of the RHIC Heavy Ion Program
search the QGP and measure its properties
map the QCD phase diagram
What have we learned
STAR NPA 757 (2005) 102
Strongly interacting, hot, dense matter with
partonic collectivity
What do we do next
Investigate the medium properties -
thermalization degree / EoS - search for chiral
symmetry restoration Search for QCD critical
point and phase boundary
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Recent STAR results highlighted in this talk
Investigation on the initial state in high energy
AA collisions Systematic studies on the bulk
properties Observation of the
anti-hypertriton More precision data on
identified particle v2 Hydro limit
reached? Search for local strong parity
violation in QCD Using calibrated probes to
learn medium properties Detailed studies on
jet-medium interaction Heavy flavor
production in pp and AA collisions
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The STAR Detector - 2? Coverage at Midrapidity
See H. Crawfords Talk Friday for STAR upgrades
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Forward-Midrapidity Di-hadron Correlations

• xg in 2-gt2 picture
• Saturation/Monojets in CGC

?0 (FMS) - ?0 (EMC) correlation
STAR Preliminary
? 0.895 0.012
? 1.09 0.03
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Observation of (anti-)hypertriton
See Z. Xus Talk Friday
S-2
S-1
S0
Never observed before

• First ever observation of an anti-hypernucleus
  (4s signal of )
• The hypertriton and anti-hypertriton lifetime

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Identified particles v2

• Mass ordering in the low pT
• Coalescence hadronization
• Multi-strange particles flowing

Partonic collectivity!
Run 7 AuAu
NCQ scaling persists in CuCu collisions
Open symbols PHENIX, PRL 98 (2007) 162301
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Ideal hydro limit reached?
AuAu 200 GeV 0 80
Hydro limit
STAR preliminary
Borghini Ollitrault, PLB 642(2006)227
v4/v22 results suggest that ideal hydro limit is
not reached.
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Search for local strong P-violation
Local strong P-violation is fundamental in QCD!
Correlation Technique P-even
The Chiral Magnetic Effect
STAR Preliminary

• In heavy ion collisions
• Quark charge separation along L.
• D. Kharzeev, PLB 633 (2006) 260
• Deconfinement
• Chiral symmetry restoration

The data is generally in agreement with
theoretical expectations for parity violation in
heavy ion collisions!
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Jets flavor conversion in medium
a) RAA(proton)gtRAA(pion) at high pT In contrast
to the prediction of color charge dependence of
Energy Loss. b) RAA(kaon) 0.4 at high
pT Consistent with the prediction of jet
conversion by interaction with the medium c)
RAA(rho)RAA(pion) at high pT Not a mass effect
See P. Netrakantis Talk Friday
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Jet-Medium Interaction Asymmetric Ridge
trigger pt3-4 GeV/c
STAR Preliminary
CEM model

• Jet is symmetric.
• Ridge is asymmetric !
• Ridge asymmetry consistent with Correlated
  Emission Model (CEM) -
• ridge may be due to jet-flow alignment.

Ridge
Asymmetry
Ridge assoc pt1-1.5 GeV/c Ridge assoc pt1.5-2
GeV/c Jet assoc pt1.5-2 GeV/c
Jet
See P. Netrakantis Talk Friday
in-plane
out-of- plane
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Direct Photon - Hadron Correlations

• Accurate measurements of energy dependence of
  energy loss
• Possible measurements of path length dependence
  of energy loss (? -jet vs ?0 -jet)

STAR Preliminary

• Direct photon yields in agreement with
  theoretical calculations
• IAA data show no strong rise at zT lt 0.6 as
  expected by one calc.

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Full Jet Reconstruction in AA
New approach for assessment of jet
quenching Several different algorithms were
implemented - comparable jet X-sec in pp
collisions with published result - more
precise estimation on background in AuAu is
underway Possible broadening of jet energy
profile in AuAu
Jet cone size
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Calibrating probe - Heavy flavor production
STAR Preliminary
STAR Preliminary
pTgt5GeV/c
CS Color Singlet CO Color Octet
STAR Preliminary
STAR measured high pT J/psi production NRQCD
CSCO agree with the measurements better, leave
little room for feed-down NNLO CS predicts
steeper pT spectra
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High pT J/psi in heavy ion collisions
H. Liu, K. Rajagopal and U.A. Wiedemann PRL 98,
182301(2007) T. Gunji, J. Phys.G 35, 104137
(2008)
X. Zhao and R. Rapp (2007), arXiv0712.2407.
S. Wicks et al., Nucl. Phys. A784, 426 (2007),
and private communication.
A. Adil and I. Vitev, Phys. Lett. B649, 139
(2007), and I. Vitev private communication
RAA(pT gt 5 GeV/c) 1.4 0.4 0.2
arXiv 0904.0439
STAR Preliminary

• Contrast to AdS/CFT Hydro prediction (99
  C.L.)
• RAA(pTgt5GeV/c) gt 0.6 (97 C.L.), indicating RAA
  increases with pT
• Color octet J/ will suffer energy loss in the
  medium - contrast to the large suppression of
  heavy flavor decay electron RAA

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Online High Level Trigger (HLT)
Run 9 pp 200 GeV, May 19 - 25

• DAQ1000 frees the band-width, and increases the
  data statistics dramatically!
• HLT allows fast analysis
• Rejection based on fast tracking and combination
  of information from other subsystems

0.24 pb-1 BHT0 0.29 pb-1 BHT2 2.3 pb-1 BHT3
Physics program benefited - high pT physics
- quarkonia - other rare probes
STAR Preliminary
We are monitoring J/ online!
See H. Crawfords Talk Friday
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Upsilon?production in dAu
RdAu 0.98 0.32 (stat.) 0.28 (sys.)

• Run8 dAu 200 GeV
• High luminosity 32nb-1
• Low material in front of TPC
• L0L2 Upsilon trigger

• Consistent with Nbin scaling
• Consistent with anti-shadowing calculations

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Search for QCD Critical point
1st-order Phase Tran. / Critical Point
Elliptic directed flow Azimuthally-sensitive
HBT Fluctuations correlations
- Kurtosis analysis on net protons

• Turn-off major sQGP signatures already
  established at top RHIC energies
• NCQ scaling
• Hadron suppression
• Pair correlations in ?f??
• Parity violation vs. vsNN

See H. Crawfords Talk Friday
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9.2 GeV Results
9.2 GeV measurements based on 4 hours and 40
minutes in year 2008 3000 good events
BES proposal gt 1000 times more statistics
Publishable quality data show particle ratios, v2
and HBT results are comparable to SPS results
STAR preliminary
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Summary

• Investigation on initial state of high energy
  nucleus
• - Forward-midrapidity di-hadron correlation
  qualitatively consistent with the CGC picture.
• First observation of anti-hypernucleus
• More precision measurements on medium bulk
  properties
• - Precision PID v2, NCQ test
• Ideal hydro limit not reached
• viscosity / entropy
• More knowledge on jet-medium interaction
  mechanisms
• Probe jet flavor conversion
• Ridge characteristics
• Full jet reconstruction
• Heavy flavor program is underway
• J/psi RCuCu consistent with unity at high pT
• Upsilon Nbin scaling in dAu
• Beam Energy Scan to map the QCD phase diagram
• - 9.2 measurements demonstrate the STAR readiness

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STAR Physics Presentations
Carl Gagliardi STAR Spin Recent Highlights
and Results Zhangbu Xu Observation of the
anti-hypertriton in the STAR experiment at
RHIC Pawan Netrakanti Jet-medium
interactions in STAR - Cone, Ridge and high pT
RAA Hank Crawford STAR Future Plans and
Upgrades