Monte Calor Study of Hard and Soft Interactions:

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Chinese New Year Feb. 7. 2008 Happy New Year
Eve! Happy Mouse Year!
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Overview of Charm production at RHIC
Yifei Zhang University of Science Technology of
China
Thanks to The conference organizers
Quark Matter 2008, Feb. 4-10, Jaipur, India
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Outline

• Introductions
• Signal/Spectra
• Flow energy loss
• Correlations
• Summary Outlook

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Why measure charm?
Mb ? 4.8 GeV
gtgt Tc, LQCD, Muds
Mc ? 1.3 GeV

• Higgs mass electro-weak symmetry breaking.
  (current quark mass)
• QCD mass Chiral symmetry breaking. (constituent
  quark mass)
• Heavy quark masses are not modified by QCD
  vacuum. Strong interactions do not affect them.
• Important tool for studying properties of the
  hot-dense matter created at RHIC energy.

Muller nucl-th/0404015
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Charm production cross-section

• Charm quarks are believed to be mainly produced
  at early stage by initial gluon fusions.
• Sensitive to initial parton distribution
  function.
• Nuclear and medium properties at initial stage.
• Precondition for light flavor thermalization if
  charm flow..
• Essential for recombination calculations of J/?
  production.

M. Gyulassy Z. Lin, PRC 51 (1995) 2177
Npart
L.Yan, P.Zhuang, N.Xu PRL 97 (2006) 232301
PHENIX data nucl-ex/0611020
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Charm measurements at RHIC

• STAR measurements
• Signal/Spectra
• D0 ? K?
• c ? ? X (y0, low pT)
• c ? e X
• Flow energy loss
• Radial flow from NPE
• RAA from NPE
• Correlations
• D-jet, e-h, e-D0

• PHENIX measurements
• Signal/Spectra
• D0 ? K-??0
• c ? ? X (ltygt1.65, pTgt1 GeV/c)
• c ? e X
• ee-
• Flow energy loss
• Elliptic flow from NPE
• RAA from NPE
• Correlations
• e-h

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Outline

• Introductions
• Signal/Spectra
• Flow energy loss
• Correlations
• Summary Outlook

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Direct D-meson reconstructions at STAR
STAR Preliminary
Section XIV A. Shabetai
K? invariant mass distribution in dAu, AuAu
minbias, CuCu minbias at 200 GeV collisions.
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Direct D-meson reconstruction at PHENIX
Reconstruct D0?K p- p0 decay in pp p0 identified
via p0 ? gg decay
Y. Akiba Heavy Quark Workshop
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Lepton from HF decay at STAR
STAR Preliminary
New CuCu D0 spectrum agree with AuAu after
number of binary scaled. Low pT muon constrains
charm cross-section.
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Lepton from HF decay at PHENIX
PHENIX PRL, 98, 172301 (2007)
PHENIX Preliminary
Y. Akiba heavy quark workshop
Section XIV D. Hornback
Electron spectrum is harder than muon spectrum,
within errors they are consistent at intermediate
pT. Systematically higher than FONLL
calculation. Integral e yield follows binary
scaling, high pT strong suppression at central
AuAu collisions.
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Heavy Quarks in pp from ee- at PHENIX
After subtraction of Cocktail -
Fit to acharm bbottom (with PYTHIA
shape) Good agreement with single e result.
arXiv0802.0050
Plenary III T. Awes
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Charm cross-section
PRL 94 (2005)
Section XIV D. Hornback
Total cross-section with large theoretical
uncertainty.
Section XIV A. Shabetai
Both STAR and PHENIX are self-consistent. STAR
results 2 times larger than PHENIX Consistent
with NLO calculation.
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Outline

• Introductions
• Signal/Spectra
• Flow energy loss
• Correlations
• Summary Outlook

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Radial flow lepton from HF decays
D0 STAR Preliminary
STAR Preliminary
Tfo 220 MeV (best fit) freeze out ealier lt?tgt
0.23 (best fit), lt0.42 (1-?). favor moderate
or small radial flow. -- dense medium, light
flavor thermalization.
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Elliptic flow v2 NPE from HF decays
PHENIX Run4
PRL, 98, 172301 (2007)
Poster A.Dion
Non-zero elliptic flow for electron from heavy
flavor decays ? indicates non-zero D v2, partonic
level collective motion. Strongly interact with
the dense medium at early stage of HI
collisions. Light flavor thermalization.
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Charm energy loss, unsolved puzzle
No direct D-meson measurement at high pT. Heavy
flavor electron suppression was observed in
several experiments. STAR and PHENIX are
consistent with each other.
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Outline

• Introductions
• Signal/Spectra
• Flow energy loss
• Correlations
• Summary Outlook

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D in jet and gluon splitting
Poster X. Dong
STAR Preliminary
STAR Preliminary
Data consistent with pQCD calculation for gluon
splitting rate.
Wrong sign and side band describe the background
well. Clear D signal is seen.
Compare to NLO cal., gluon splitting to total
charm production at RHIC is small.
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e-h correlations conical emission
Trigger on NPE from heavy quark decays.
Section XIII G. Wang
AuAu 200 GeV
CuCu 200 GeV
STAR Preliminary
Does heavy quark e-loss generate Mach Cone
emission?
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e-h correlations bottom contribution
Session XIV Y. Morino
Section XIII G. Wang
Simulation c?e, b?e, cb?e
Extract b/c ratio from the data/simulation
comparison
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e-h correlations bottom contribution
(b?e)/(c?eb?e)
Section XIII G. Wang Section XIV A. Mischke
Session XIV Y. Morino
Good agreement among different analyses. Data
consistent with FONLL.
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Does bottom affect charm X-sec?
STAR Preliminary
Before subtraction
(AuAu MB) (AuAu 0-12)
After bottom contribution subtraction
(AuAu MB) (AuAu 0-12)
Bottom contribution does NOT change charm
cross-section
(b?e)/(bc?e) upper limit of NLO is applied
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Summary

• Charm cross-section is found to follow number of
  binary collisions scaling, STAR and PHENIX are
  not consistent with each other.
• None zero charm flow is observed at RHIC energy.
• Electron suppression is observed at RHIC but the
  energy loss mechanism is still NOT really
  understood.
• Abounding correlations related to heavy flavor
  are reported.

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Outlook
Charm is charming, since there are lots of things
unknown! Both STAR and PHENIX are upgrading! LHC
is coming! We will have a bright future!
THANK YOU!