TWO PARTICLE CORRELATION MEASUREMENTS AT PHENIX
Takahito Todoroki For the PHENIX CollaborationUniversity of Tsukuba & RIKEN Nishina Center
Hard Probes 2012 at Cagliari, Italy
28 May 2012 Hard Probes 2012 1
Contents•Higher harmonic event plane and flow(vn)•Correlations with vn subtractions•Correlations relative to event plane
-At high and intermediate pT
•Summary
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Motivations•Dissect possible interplay of hard-scattered partons & hot dense medium
•To have definitive answer what remains in correlations after vn subtractions
•To test path length dependence of parton energy loss via correlations relative to event plane
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Initial state of collisions
• Initial collision geometry- Smooth to Fluctuating picture
• Azimuthal particle distribution- vn(even){F2} only ⟶ vn(even){Fn} + vn(odd) {Fn}
Smooth picture Fluctuating picture
F2
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• v3 is comparable to v2 at 0~10%• v2 evolution as centrality increment, no evolution in v3 • v4{F4} ~ 2 x v4{F2}
Charged particle vn : ||<0.35Event plane Fn : ||=1.0~2.8
PRL.107.252301
Charged Hadron vn at PHENIX28 May 2012 Hard Probes 2012 5
Identified Particle vn
• Mass dependence at low pT : Hydrodynamics• Baryon/Meson diff. at mid pT: Quark Coalescence
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vn contributions in correlations
• Contributions from vn :• Ridge & Shoulder positions : Agree with v3 peaks• vn subtractions needed to get real jet correlations
Ridge
2< pTasso < pT
trig GeV/C
Phys. Rev. C 80, 064912 (2009)Phys. Rev. C 78, 014901 (2008)
○:p+p●: Au+Au
Shoulder
v2 subtracted
n=3 n=3
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Correlations with D gap
•vn reproduce Ridge & Shoulder at 0-5%
Track at ||<2.5 with EP from full FCAL 3.3<||<4.8
vn with EP Method
vn with 2Par. Cor Method Charged particle pair with large rapidity gap e.g. |D|>2
Pb+Pb 2.76TeV
No
Flow
Sub
trac
tion
○ measured correlations
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QM’11 J. Jia ATLAS Flow Plenary
Correlations without D gap
•Away side shoulders are almost gone in most-central collisions 0-20%
Incl.g - hadron2-3x1-2 GeV/c
PHENIX PRELIMINARY Au+Au 200GeV 0-20%
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|D|<0.7
Correlations up to centrality 50%
• Away side shoulders - Canceled in most-central collisions : 0-10%- Remain in mid-central collisions : 20-50%
• To Do : Include v1 term to vn modulation for definitive answer
V2, V3 & V4(F4) modulationby ZYAM method
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Correlations relative to event plane
•Control parton path length-By selecting trigger relative to forward event plane
-Reduce autocorrelations of jet itself
ft
fa
Df
Fn
fs
Mid rapidity Forward rapidity
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High pT range
•Near side yield : No suppression•Away side yield : Monotonic decrease
I AA =
YA
A/Y
ppShort path
lengthLong path
length
PRC.84.024904
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v2 & v4{F2} modulatedAu+Au 200GeV 20-60%
Intermediate pT range
•Constant suppression of back-to-back jet•Two competitive effects seen
F2 R.P. F2 R.P.
Trig.
Trig.
Trig.
Trig.
in-plane trigger case
out-of-plane trigger case
Au+Au 200GeV 20-50%h-h :2-4x1-2GeV/cv2 & v4{F2} modulated
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PHENIX preliminary
Flow subtracted yield is shown radially with base line.
penetration dominancesurface dominance
Summary• Higher harmonic flow vn has been measured• By vn modulation to correlations,
- Shoulders almost gone in most-central collisions
- Shoulders remain in mid-central collisions• Correlations relative to event plane
- Monotonic away side suppression at high pT
- Constant suppression of di-jet & Two competitive effects at intermediate pT
• Fully vn modulated analyses are in progress
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Backup Slides
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Fi - Fj correlations 28 May 2012 Hard Probes 2012 16
PRL.107.252301
vn via event plane method
•Mid rapidity particle anisotropy relative to forward event planes
0 5-5
ZDC/SMD
dN/d
RXN in: 1.5<||<2.8 & out: 1.0<||<1.5
MPC: 3.1<||<3.7
BBC: 3.0<||<3.9
CNT: ||<0.35
2cm Pb converter in front
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RXN
Degeneracy among models disentangled by v3
• v3 seems to prefer low viscosity- Glauber+4p/s =1 works better
- CGC-KLN+4p/s =2 failed
• More constraints to hydrodynamics calculations
V2
V3
PRL.107.252301 (ppg132)B. Alver et. al., PRC82, 034913(2010).B. Schenke et. al., PRL106, 042301(2011).H. Petersen et. al., PRC82, 041901(2010).
(Event Plane Method)
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QM’11 J. Jia ATLAS Flow Plenary
Scaling property of v2
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Scaling property of vn
•vn(KET/nq)/nq failed on v3, v4 & v4{F2}•vn(KET/nq)/nq
n/2 : need correction power
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Fourier decomposition of flow subtracted correlations
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Correlations relative to F3
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