Heavy quark and J production at RHICPHENIX

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Heavy quark and J/? production at RHIC/PHENIX

• Outline
• Motivation
• PHENIX detector
• Open heavy quark measurements
• Heavy quarkonia measurements
• Summary

• Tsuguchika TABARU
• RIKEN BNL Research Center
• for the collaboration

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Motivation open heavy quark

• Open heavy quark measurement provides information
  of
• Cold nuclear matter effect (p-p, d-Au)
• Cronin effect.
• (Anti-) shadowing.
• Absorption.
• Hot/dense matter effect (HI)
• Energy loss
• Thermalization
• Thermal production
• Need systematic study for entanglement.

hA
g
c
(a)
_
c
g
(c)
(b)
hB
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Motivation - Heavy quarkonia

• Heavy quarkonia measurement
• p-p, d-Au collisions
• 1. Production mechanism of quarkonia.
• Color octet/evaporation.
• 2. Other cold matter effect (d-Au).
• Heavy ion collisions
• 3. Quark deconfinement
• Quark coalescence
• Other hot/dense matter effect (HI)
• Need systematic study with open heavy quark
  measurement.

NA50hep-ex/0412036
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The PHENIX detector

• A composite detector to measure leptons, photons
  and hadrons.

Beam
Beam
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The PHENIX detector

• Event trigger is defined by beam-beam counters.

Beam-beam counters
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The PHENIX detector

• Muon arms
• tracking chambers
• Muon ID detectors

Muon arm
Muon arm
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The PHENIX detector

• Central arms
• Tracking chambers
• RICH counters

Central arm
EM calorimeters TOF counters
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Open heavy quark measurement

• Today, open heavy quarks are measured by the
  semi-leptonic (electron) decay channel.
• In the future,
• Hadronic decay ? direct measurement of D mesons.
• ?, e-? ? other kinematical regions.

?
Semi-leptonic decay channel
g
c
e,?
medium
s,d
g
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Electron ID

• Electrons are identified by RICH and EMCal E-p
  matching, position matching, shower shape cut.

Au-Au data
All charged tracks
Apply RICH cut
r? cm
Real
Net signal
Accidental background
z cm
RICH ring shape (signal accumulated)
Energy-Momentum GeV
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Extraction method

• All physical backgrounds (BG) were evaluated by
  Monte-Carlo calculation using real PHENIX data.
• Low pT ? Small S/N, Challenging
• High pT ? Good S/N

BG (sum)
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Result p-p collisions at 200 GeV

• Signal e? spectrum with PYTHIA calculation (tuned
  to lower energy data lt62 GeV ).

PHENIX PRELIMINARY
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Result p-p collisions at 200 GeV

• Signal e? spectrum with PYTHIA calculation (tuned
  to lower energy data lt62 GeV ).

In good agreement
PHENIX PRELIMINARY
Harder than PYTHIA
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Result d-Au collisions at 200 GeV

• Spectra agree with p-p data after applying binary
  scaling.
• No significant cold nuclear medium effect in the
  uncertainty.

The d-Au data is scaled by number of binary
collisions.
Non-photonic electrons from heavy quarks (main
part), light vector mesons and kaons (small
fractions).
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Result Au-Au collisions at 62.4 GeV

• Spectra agree with the ISR p-p data scaled by TAB
  with uncertainty.

PHENIX PRELIMINARY
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Result Au-Au collisions at 200 GeV
Differential CS

• Small statistics in high pT.
• Integrated charm production cross section in
  Au-Au agree with p-p cross sections scaled by
  binary-collisions.

nucl-ex/0409028
Integrated CS (0.8ltpTlt4 GeV/c)
Integrate
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Result Au-Au collisions at 200 GeV

• The nuclear modification factor (RAA) have the
  same tendency with ?0.

• Result using full statistics.
• Single electrons in high pT region seem
  suppressed.

RAA of Integrated CS (2.5ltpTlt5.0 GeV/c).
PHENIX PRELIMINARY
Integrate
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Single electron v2 component

• The elliptic flow comes from pressure.

High pressure
(Like ellipticity)
Low pressure
The ?R is the angle between reaction plane and
y0.
Z
Reaction plane Z-X plane
If heavy quarks are thermalized ? Elliptic flow
(or v2) of D meson ? Single electron v2.
Flow
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Result Au-Au collisions at 200 GeV

• Non-photonic single electron flow (v2 component)
  can come from both light and heavy quarks.
• To determine the charm
• flow, need more
• statistics.

v2 from light c quarks
v2 from light quarks
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Summary open charm measurement

• The heavy quark production CS is harder in 1.5ltpT
  than PYTHIA tuned at the ISR data (p-p data).
• No significant cold matter effect is seen within
  the uncertainty (d-Au data).
• The integrated charm yield in the mid-rapidity is
  consistent with binary collision scaling (Au-Au
  data).
• In high pT region (2.5 GeV or more), the charm
  yield is small compared to p-p data (Au-Au 200
  GeV data).
• The charm flow (v2) measurement is on going.
  Need more statistics (Au-Au data).

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J/? measurement

• J/? ? ee? at mid rapidity
• J/? ???? at forward and backward rapidity.

PRL92(2004)051802
d-Au at 200 GeV
ee?
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J/? spin alignment

• J/? spin alignment ? positron angular
• distribution in J/? rest frame.

transverse
Angular distribution
longitudinal
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J/? spin alignment

• Measured in d-Au 200 GeV data.
• Expected no or small alignment at low pT.
• Need more data.

PHENIX PRELIMINARY
transverse
?
longitudinal
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(Anti-) shadowing in d-Au collisions
Example of predicted gluon shadowing in dAu
rapidity y
X2
X1
J/? in South y lt 0
gluons in Pb / gluons in p
J/? in Central y 0
X1
X2
X
(Anti-) shadowing can be seen!
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Cross section and modification factor

• Weak shadowing?

PHENIX PRELIMINARY
PHENIX PRELIMINARY
Klein,Vogt, PRL 91142301,2003 Kopeliovich, NP
A696669,2001
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Mass number dependence (y)

• Weaker absorption compared to lower vs?
• Absorption and shadowing are difficult to
  disentangle.

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J/? measurement in Au-Au collisions

• The analysis for J/? is on going (2004 data).
• About 600 J/? are expected in ee? data.

Au-Au at 200 GeV in ee-
1/8 of statistics
Unlike-sign pairs
Like-sign pairs
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Summary J/? measurement

• The J/? production cross sections were measured
  in p-p, d-Au and Au-Au collisions, and published.
• The J/? spin alignment was measured in d-Au
  collisions. No spin alignment was seen within
  the uncertainty.
• The J/? seems suppressed in d going direction in
  d-Au collisions. But, the entanglement between
  absorption and shadowing.
• For hot/dense matter effect, we are analyzing
  2004 data.

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Brazil University of São Paulo, São
Paulo China Academia Sinica, Taipei,
Taiwan China Institute of
Atomic Energy, Beijing Peking
University, Beijing France LPC, University
de Clermont-Ferrand, Clermont-Ferrand
Dapnia, CEA Saclay, Gif-sur-Yvette
IPN-Orsay, Universite Paris Sud,
CNRS-IN2P3, Orsay
LLR, Ecòle Polytechnique, CNRS-IN2P3, Palaiseau
SUBATECH, Ecòle des Mines at
Nantes, Nantes Germany University of Münster,
Münster Hungary Central Research Institute for
Physics (KFKI), Budapest
Debrecen University, Debrecen
Eötvös Loránd University (ELTE), Budapest India
Banaras Hindu University, Banaras
Bhabha Atomic Research Centre,
Bombay Israel Weizmann Institute,
Rehovot Japan Center for Nuclear Study,
University of Tokyo, Tokyo
Hiroshima University, Higashi-Hiroshima
KEK, Institute for High Energy Physics,
Tsukuba Kyoto University,
Kyoto Nagasaki Institute of
Applied Science, Nagasaki
RIKEN, Institute for Physical and Chemical
Research, Wako RIKEN-BNL
Research Center, Upton, NY
Rikkyo University, Tokyo, Japan
Tokyo Institute of Technology,
Tokyo University of Tsukuba,
Tsukuba Waseda University,
Tokyo S. Korea Cyclotron
Application Laboratory, KAERI, Seoul
Kangnung National University, Kangnung
Korea University, Seoul
Myong Ji University, Yongin City
System Electronics Laboratory, Seoul Nat.
University, Seoul Yonsei
University, Seoul Russia Institute of High
Energy Physics, Protovino
Joint Institute for Nuclear Research, Dubna
Kurchatov Institute, Moscow
PNPI, St. Petersburg Nuclear Physics
Institute, St. Petersburg St.
Petersburg State Technical University, St.
Petersburg Sweden Lund University, Lund
12 Countries 58 Institutions 480
Participants
USA Abilene Christian University, Abilene, TX
Brookhaven National Laboratory,
Upton, NY University of California
- Riverside, Riverside, CA
University of Colorado, Boulder, CO
Columbia University, Nevis Laboratories,
Irvington, NY Florida State
University, Tallahassee, FL Florida
Technical University, Melbourne, FL
Georgia State University, Atlanta, GA
University of Illinois Urbana Champaign,
Urbana-Champaign, IL Iowa State
University and Ames Laboratory, Ames, IA
Los Alamos National Laboratory, Los Alamos,
NM Lawrence Livermore National
Laboratory, Livermore, CA University
of New Mexico, Albuquerque, NM New
Mexico State University, Las Cruces, NM
Dept. of Chemistry, Stony Brook Univ., Stony
Brook, NY Dept. Phys. and Astronomy,
Stony Brook Univ., Stony Brook, NY
Oak Ridge National Laboratory, Oak Ridge, TN
University of Tennessee, Knoxville, TN
Vanderbilt University, Nashville, TN
as of January 2004
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The end
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Extraction method converter subtraction

• The ?-conversion, ?0 and ? Dalitz decays ?
  evaluated by installing extra conversion
  material.
• The other BG ? evaluated by MC using PHENIX data.

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Result d-Au collisions at 200 GeV
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Single e RdAu from STAR
Nucl-ex/00404019
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200 GeV Au-Au single electron cocktail
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RAA for each centrality bin
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Comparison with theoretical model

• The average transverse momentum squared
  transferred from the medium per mean free path
  length.
• (hep-ph/0405184)

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Single e v2 from STAR
Nucl-ex/0411007
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History of PHENIX J/? yields
Phys.Rev.Lett 92, 051802 (2004)
Cross section
Phys.Rev.C69,04901 (2004)
Cold nuclear matter effect,
Hot/dense matter effect. Coming soon
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Run2 p-p J/?
Width 160 MeV
Width 110 MeV
The centroid error comes from uncertainty of
magnetic field map.
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(central / peripheral) versus Ncoll

• define four centrality classes for dAu
  collisions
• determine Ncoll for each class in a
  Glauber model
• calculate Rcp

Rcp
High x2 0.09

• low and medium x2
• weak nuclear effects
• small (shadowing) centrality dep.
• high x2
• steep rise with centrality
• how can anti-shadowing rise so steeply while
  shadowing does not?
• final state effect in Au remnants (close to Au
  frame)?

Low x2 0.003
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Mass number dependence (pT)

• Increase of a with increasing pT (Cronin-like
  effect)
• similar to measurements at lower energy
  (E866 vs 39 GeV)

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Disentanglement
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Heavy quark production
hA
g
c
_
c
g
hB

• Sensitive to the initial gluon density
• (Anti) shadowing ? enhancement/suppression.

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Heavy quark production in cold nuclei
Colliding nuclei
hA
Colliding nuclei
g
c
_
c
g
hB

• Normal hadron reactions, by d-Au and p-p
  collisions.
• Cronin effect ? enhancement at pT26 GeV/c.
• Absorption ? suppression.

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Heavy quarks in hot/dense matter
hA
Hot/dense medium
g
c
_
c
g
hB

• Travel through produced media in heavy ion
  collisions
• Energy loss ? softening of pT spectra or
  absorption.
• Thermalization ? flow.

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Thermal production
Hot/dense medium
g
c
_
c
g

• Thermal production ? enhancement, H.B.T.

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Heavy quarkonia production
hA
g
c
J/?
_
c
g
hB

• Production mechanism of J/?
• Color octet/evaporation ? J/? polarization and
  yield.

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J/? suppression
hA
Hot/dense medium
g
c
_
g
c
hB

• Deconfined partons ? color screening in Au-Au
  collisions ? J/? suppression.
• Need d-Au, p-p J/? data, and open charm data as
  the baseline data.

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Coalescence
Hot/dense medium
g
c
J/?
_
c
g

• Production by coalescence ? J/? enhancement (in
  high pT?).