Di-hadron and three-particle correlations at RHIC. Pawan Kumar Netrakanti Nuclear Physics Division B.A.R.C., Mumbai. The “Ridge” & “Cone” Theoretical model expectations 2- and 3-particle correlation results Reaction plane dependence Ridge and Cone Summary. Outline. WPCF-2011 - PowerPoint PPT Presentation
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The “Ridge” & “Cone”Theoretical model expectations2- and 3-particle correlation results
Reaction plane dependenceRidge and Cone
Summary
Di-hadron and three-particle correlations at RHIC
Pawan Kumar Netrakanti Nuclear Physics Division
B.A.R.C., Mumbai
Outline
WPCF-2011September 20th -24th, Tokyo
“Ridge” : Near-side correlations
Near-side “ridge” in central Au+Au collisions. Properties similar to bulkExtends even upto higher rapidities. Long range correlations.Ridge persists to very high pT trigger particle
d+Au Au+Au0-12%
QM09
pTTrig > 4 GeV/c
2<pTAssoc<pT
Trig GeV/cPhys. Rev. C 80 (2009) 064912.
04/21/232
“Ridge” : Theoretical model expectations
3
1)In medium radiation + longitudinal flow pushN.Armesto et.al Phys.Rev.Lett.93(2004) 242301
2)Turbulent color fields A.Majumder et.alPhys. Rev. Lett.99(2004)042301
4) Momentum Kick C.Y. Wong hep-ph:0712.3282
3) Recombination between thermal and shower partonsR.C. Hwa & C.B. Chiu Phys. Rev. C 72 (2005) 034903
Evolution of double peak structure from in-plane to out-of-plane Dihadron correlations w.r.t. 2 and 3 may indicate path-length/geometry effects Physics mechanism still under debate.
Summary
15Thank you
Jet and Ridge are “separated” by using the charge dependence. Ridge broad and uniform, jet narrow in . Ridge production appears to be uncorrelated to the presence of the jet. Ridge may have the path length dependence.
“Ridge”
“Cone”
Study of correlation of particles has improved the understanding of the heavy-ion collisions.
04/21/23
Back up
04/21/2316
Triangular flow
Odd harmonics may not be neglected.
ALICE, PRL 107, 032301 (2011)
17
Alver, Roland, PRC 81, 054905 (2010)
dN/d = 1 + 2v22cos(2) + 2v3
2cos(3) + 2v42cos(4)….
“Cone” : Theoretical model expectations
18Away-side
Mach Cone :• Mach angle depends on speed of sound
in medium • T dependent
• Angle independent of associated pT.
cvp
c partons
;2
M
parton
s
v
c cos
Trigger
MM
PNJL Model
Cerenkov gluon radiation : Gluons radiated by superluminal partons. Angle is dependent on emitted momentum.
)(
1
)(cos
pnvpn
c
v
c
partonc
parton
n Čerenkov angle vs emitted particle momentumI.M. Dremin (Nucl. Phys. A750: 233, 2006)
V. Koch et. al. (Phys. ReV. Lett. 96, 172302, 2006)
Can we distinguish between these physics interpretations? 3-particle correlation in
Medium
away
near
di-jets
2-particle correlation 3-particle correlation
Mediumaway
near
deflected jets
away
near
Medium
Conical Emission
vn subtracted dihadron Correlations(pT
trig=3-4 GeV/c, pTassoc=1-2 GeV/c, large ||>1)
Remark: Associated pT range ~ pTref. Case of data-data=0: jet-correl nonflow is
subtracted; what’s left are similar between centralities, and resemble a v1 component.
19
Au+Au80-50%
50-20% ZDC 12%
pTref=0.2-5 GeV/c
ALICE, PRL 107 (2011)
STAR Preliminary STAR Preliminary STAR Preliminary
Simple background normalization: average signal = 0.
vn subtracted dihadron correlations(pT
trig=3-6 GeV/c, pTassoc=2-3 GeV/c, ||>1)
Bkgd subtracted using two-particle vn{2} (flow+fluctuation). vn{4} may not be very relevant: fluctuation effect is negative; v3{4}~0. Near-side ridge in central collisions seems still visible. Ridge may be not
entirely due to vn. Away-side is suppressed at high-pT in central collisions. Shape modification at
intermediate-low pT. Residual non-flow should be present in the measured vn. Important next step is
to separate non-flow contribution.20
80-50%50-20% ZDC 12%
STAR Preliminary STAR Preliminary STAR Preliminary
Simple background normalization: <signal> = 0.
04/21/2321
Hydro, Boltzmann calculations: J. –Y. Ollitrault
STAR: Aihong Tang, Proc.24th Winter Workshop on Nuclear Dynamics