High pT identified charged hadron v2 and v4 in 200GeV AuAu collisions by the PHENIX experiment

1
High pT identified charged hadron v2 and v4 in
200GeV AuAu collisions by the PHENIX experiment

• Shengli Huang
• Vanderbilt University
• for the PHENIX Collaboration

2
Outline

• Observables and Motivation
• Analysis methods
• Results and Discussion
• Conclusions

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Anisotropic flow v2 and v4
Peter Kolb, PRC 68, 031902

• Azimuthal correlation with the reaction plane
• Built up in the early stage and self-quenched,
  therefore supply the early information of matter
  generated in the collision

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Partonic Flow
PHENIX, PRL. 99, 052301 (2007)
baryon
meson

• Baryon and meson elliptic flow follow the number
  of constituent quark scaling as a function of
  KET. This indicates that partonic flow builds up
  at RHIC
• Where is the break point where the hydro
  interfaces with jet fragmentation?
• The medium density and strength of interactions
  ?The dynamic range of the
• global partonic flow
• How about the higher order anisotropic flow such
  as v4?

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V4/(v2)2 ratio

• v4 /v22 is a probe of ideal
• hydro behavior and related to
• the degree of thermalization!
• Peter Kolb, PRC 68, 031902
• R.S.Bhalerao et.al PLB 627,49
• Borghini and Ollitrault, PLB642,227
• Hydro dynamics predicts
• v4 /v22 0.5
• The identified particles
• v4/v22 ratio should provide more
• detailed information than
• that of charged hadron

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How to Coalesce?
b) Different momentum space
a) Similar momentum space
? modification factor
L.W. Chen, C.M. Ko nucl-th 0602025

• The measurement of meson and baron v4 /v22 ratio
• will allow us to extract the partonic v4,q
  /v2,q2 ratio
• To test whether the partons in different momentum
  
• space also can recombine with each other

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PHENIX in Run 7

• Run 7
• 4.5B events and around 50 have been used
• A new Time of Flight detector (TOFw) has been
  installed in
• the west arm of PHENIX
• A new reaction plane detector (RxNP) has been
  installed in
• the 38 cm lt z lt 42 cm alone the beam

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TOFw and Aerogel Detectors

• TOFw intrinsic timing resolution is 75ps
• ?/K can be separated to 2.8 GeV/c and K/p can be
  separated
• to 4.5 GeV/c
• 3. Together with Aerogel detector(ACC), we can
  identify the K to
• pT4 GeV/c and ?, p to 7 GeV/c

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Reaction Plane Measurements

• RxNP
• Two sets of plastic
• scintillators positioned
• on either side of the
• collision vertex
• 12 segments in ?
• 2 segments in ?
• 1.0 lt ? lt 1.5
• 1.5 lt ? lt 2.8
• BBC
• 3.1lt?lt3.9
• Both detectors are away from mid-rapidity.
  Smaller non-flow effect
• on the reaction plane measurements
• New RxNP detector resolution is around 74 at
  mid-centrality

Sqrt(2cos(2(?N-?S)))
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Mass ordering of v2 and v4

• V4 has been measured as a
• function of pT in different centrality bins for
  the ?, K and p
• Mass ordering has been observed for both v2 and
  v4
• Consistent with the hydrodynamics
• Poster 166 A.Taranenko

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KET Scaling of v4
P166 A.Taranenko

• The v4 follows the KET scaling well for KET lt 1
  GeV
• The number of constituent quark scaling holds
  for v4 when
• KET/nq lt 1 GeV. This confirms that matter with
  partonic degrees
• of freedom has been generated at RHIC

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V4/(v2)2 ratio

• The ratio of v4/(v2)2 is close to
• 0.9 for the ?, K and p
• Mesons and baryons have similar
• v4/(v2)2 ratio

What can we extract from this measurement?
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Partonic Thermalization !

• Parton v4,q/(v2,q)20.5 Perfect Partonic
  Liquid!
• Partons in different momentum space also can
• recombine with each other
• 3. Partons interact more frequently and strongly
• with each other

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Charged ? v2

• Charged ? v2 can be measured to
• 6 GeV/c.
• The results are consistent with
• ?0 results in the overlap pT region.
• All ? v2 start to drop at pT 2.5 GeV/c
• in the different centrality bins!

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Kaon and Proton v2

• Kaon v2 can be measured to 4 GeV/c and protons v2
  can be measured to 6 GeV/c
• Proton v2 starts to drop at pT 4 GeV/c

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Break Point?
KET/nq(GeV)
KET/nq(GeV)

• In the centrality of 2060, the ?, K and p KET
  scaling seemly begins to
• break at KET/nq 1 GeV
• More statistics are required for the further
  investigation
• A factor 2 of Run 7 data
  will come after QM08

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Conclusions
New time of flight detector(TOFw) of PHENIX runs
successfully in Run 7 with 75 ps intrinsic timing
resolution. With new TOFw and RxNP detectors, we
can measure the identified charged hadrons v2 to
pT6 GeV/c and v4 to 3 GeV/c
The number of constituent quark scaling has been
observed for v4 for KET/nq lt 1 GeV. Mesons and
bayrons have similar v4/(v2)2 ratio which is
close to 0.9 The parton v4,q/(v2,q)2 0.5
perfect partonic liquid Partonic Thermalization
The number of constituent quark scaling seemly
begins to break for v2 as KET/nq1GeV at 2060
centrality a)The interface between hydro and jet
fragmentation b)Quantitative information about
density and interaction strength