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Unveiling Jet Topology via Multi-Unveiling Jet Topology via Multi-Particle CorrelationsParticle Correlations
N. N. Ajitanand
Nuclear Chemistry, SUNY, Stony Brook
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A Cue from Lattice QCD:A Cue from Lattice QCD:
A Cue from Lattice QCD:A Cue from Lattice QCD:
Phase Transition
12 °
3
170 MeV 10 K
1 GeV/fm
T
Brief historical perspective : Brief historical perspective : Brief historical perspective : Brief historical perspective :
For phase transition to occur necessary to create For phase transition to occur necessary to create energy density > 0.6 – 1.0 GeV/fmenergy density > 0.6 – 1.0 GeV/fm3 3
For phase transition to occur necessary to create For phase transition to occur necessary to create energy density > 0.6 – 1.0 GeV/fmenergy density > 0.6 – 1.0 GeV/fm3 3
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N. N. Ajitanand Jyvaskyla 2007 3
PRL87, 052301 (2001)
Central collisionsperipheral collisions
time to thermalize the system (0 ~ 0.2 - 1 fm/c)Bjorken~ 5 - 15
GeV/fm3
~ 35 – 100 ε0
dy
dE
RT
Bj0
2
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Extrapolation From EExtrapolation From ETT
DistributionsDistributions
Achieved Energy Density is Well Above theAchieved Energy Density is Well Above the Predicted Value for the Phase TransitionPredicted Value for the Phase Transition
Achieved Energy Density is Well Above theAchieved Energy Density is Well Above the Predicted Value for the Phase TransitionPredicted Value for the Phase Transition
200 GeV Au+Au Collisions 200 GeV Au+Au Collisions studies at RHIC!studies at RHIC!
200 GeV Au+Au Collisions 200 GeV Au+Au Collisions studies at RHIC!studies at RHIC!
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N. N. Ajitanand Jyvaskyla 2007 4
Quark scaling of v2 indicates flow sets in at the partonic stage
Strong quenching observed for high pt hadrons
hydro-like flow observed
0.00
0.05
0.10
0.15
0.20
0.25
0.4
0.8
1.21.6
2.0
510
1520
2530
v 2
pT (GeV/c)
Centrality (%)
0.00 0.05 0.10 0.15 0.20 0.25
Au+Au
200 GeVNNs Baryons
s/
P ²
High Energy Density matter produced in 200 GeV Au + Au
High Energy Density matter produced in 200 GeV Au + Au
Initial anisotropy gives large pressure gradients
Initial anisotropy gives large pressure gradients
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N. N. Ajitanand Jyvaskyla 2007 5
Even the phi which has a very low hadronic scattering cross-section develops a v2 which scales with the mesons. Strong indication of flow developing at the partonic stage
Phi meson Flow
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N. N. Ajitanand Jyvaskyla 2007 6
lambdas and cascades also show strong v2 according to the expected scaling pattern further supporting the view that flow sets in at the partonic stage
Lambda & Cascade Flow
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N. N. Ajitanand Jyvaskyla 2007 7
Observation of significant flow for the D meson which implies charm flow
D Meson Flow
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N. N. Ajitanand Jyvaskyla 2007 8
G. D. Moore, D. Teaney hep-ph/0412346
Calculation of the charm spectrum and the elliptic flow as a function of the diffusion coefficient implies surprisingly strong rescattering behaviour for the heavy quark. An indication of the rather special attributes of the matter formed. Strongly coupled liquid ?
Charm Diffusion
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Although a part of this effect may be trivially related to the contribution of resonances, the possibility of medium modification contributions is an interesting area of investigation.
PHENIX Data to be published in PRL
One way to do this would be to look at the source function at different orientations with respect to a high pt particle
Imaging Studies
Source functions extracted for charged pions produced in Au+Au collisions show non-Gaussian tails.
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N. N. Ajitanand Jyvaskyla 2007 10
Such a low value is consistent with the observation of substantial elliptic flow and may provide the conditions for a special medium response to hard probes such as Mach flow
R. Lacey et al. Phys. Rev. Lett. 98,092301 (2007)
The shear viscosity to entropy ratio (eta /s) is estimated for the hot and dense QCD matter created in 200 GeV Au+Au collisions at RHIC . A very low value ~0.1 is found which is close to the conjectured lower bound (1/4 pi )
Shear viscosity to Entropy ratio
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N. N. Ajitanand Jyvaskyla 2007 11
There is strong evidence to support the view that the medium thermalizes rapidly during the partonic stage and
exhibits a high degree of collectivity.
Study of the medium response to high
pT probes is a natural next step
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Jets are a natural probe of the Medium
coneRFragmentation:
z hadron
parton
p
p
In relatvistic heavy ion collisions hard parton-parton processes occur early
Following hard collisions, scattered partons propagate through the medium radiating gluons and interacting with partons of the medium
Finally partons fragment, (possibly) outside the medium
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Jet Study via AssortedJet Study via Assorted CorrelationsCorrelations
Associated low pT particle
1.0 2.5 GeV/cpT 1.0 2.5 GeV/cpT
pT
2 ( )P assor High pT Hadron
2.5 4.0 GeV/cpT 2.5 4.0 GeV/cpT
Re al
mix
NC
N
Correlation FunctionCorrelation Function
N(pT)
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N. N. Ajitanand Jyvaskyla 2007 14
It is necessary to decompose the correlation function to obtain
the Jet Function!
H(v2)Obtain Obtain
using BBC Reaction PlaneLarge η gap
Two source model gives :
0
HarmoC Jet Functiorrelation Function onic n
C a H J
Correlation Flow Jet Correlation Jet
Sets a0
min 0J
Condition Zero Yield At Minimum
Evaluate a0
nucl-ex/0501025 Ajitanand et. al.
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Simulation Test of Jet Recovery
Di-jet faithfully recoveredDi-jet faithfully recovered
Normal Jet Shape abnormal Jet Shape
Line : Input Jet Correlation
Squares : Extracted Jet Correlation
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200 GeV Au+Au : Hadron Jet Shapes
Jet-pair distributions resulting from decomposition showJet-pair distributions resulting from decomposition showsignificant modificationsignificant modification
Jet-pair distributions resulting from decomposition showJet-pair distributions resulting from decomposition showsignificant modificationsignificant modification
PRL 97, 052301 (2006)
200 GeV Au+Au
1<pT<2.5
vs
2.5<pT<4.0
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MesonMeson vs. vs. BaryonBaryon associated partner (for fixed Hadron associated partner (for fixed Hadron trigger)trigger)
Associated mesons and baryons are similarly modified as would be expectedAssociated mesons and baryons are similarly modified as would be expectedIf in-medium modification is the cause of the away side bending If in-medium modification is the cause of the away side bending
PHENIX Preliminary
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Armesto,Salgado,Wiedemann hep-ph/0411341
Possible Modifications of Jet Topology
Mach Cone,Wake Effect or “sonic boom” Mach Cone,Wake Effect or “sonic boom”
Stoecker nucl-th/0406018
Muller,Ruppert Hep-ph/0503158
Casalderrey-Solana, Shuryak, Teaney, arXiv hep ph/0411315 (2004)
Flow induced Deflection Flow induced Deflection
Cherenkov Cone Cherenkov Cone A. Majumdar Hard Probes 2006
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J. Friess, S. Gubser, G. Michalogiorgakis, S. Pufu
hep-th/0607022
Graviton perturbations of AdS_5-Schwarzschild generated by a string trailing behind an external quark moving with constant velocity are studied. Mach cone signals are generated in the medium
Components of the stress tensor exhibit directional structures in Fourier space at both large and small momentum. The Mach cone angle seen is similar to that in the experiment
ADS-CFT duality
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N. N. Ajitanand Jyvaskyla 2007 20
Dip
Sh
ould
er
Sh
ould
er
Identify “Mach Cone ” region with shoulder and normal jet region with dip
Analysing two-particle Jet correlations from Mach cone perspective
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Dip to Shoulder ratio vs pT for different trigger pT ranges
Behaviour for Au+Au is quite different from p+p indicating medium modification
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Shoulder does not quench rapidly medium dominanceDip quenches rapidly jet dominance
The away side Icp
( )
( )cent
peripheralCP
PerTrigYield
PerTrigYieldI
Ratio of per-trigger yield: Icp
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along azimuth
Polar plot
3 Particle Correlations in High pT Framework (*)
Normal Jet
Same Side
Away Side
*
*
Assoc. pTs (2,3)
*12
* =
along radius
*12
*13
* _=
Hi pT(1)
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Deflected jet sim
3-Particle di-jet correlations allow a distinction between different mechanistic scenarios !
Mach Cone sim
Deflected and Cone Jet Sims
2-particle Correlations matched
High pT(1) High pT(1)
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PHENIX SIMTest of Harmonic removal
Jet+Harmonic
ZYAM gives good Jet Recovery
Input Jet Harmonic removed
Jet Correlation = Total Correlation – a0*(Harmonic Jet Correlation = Total Correlation – a0*(Harmonic Correlation)Correlation)
““ao” is adjusted till ao” is adjusted till Jet Correlation surfaceJet Correlation surface goes to zero at goes to zero at its minimum (ZYAM )its minimum (ZYAM )
Ajitanand et.al. Phys. Rev. C 72, 011902 (2005)Phys. Rev. C 72, 011902 (2005)
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Blue : Input
Red : Recovered
True 3P correlations True 3P correlations successfully recovered successfully recovered
(2+1) correlations obtained taking 2P in event 1 and 1P from event 2
For data relative amounts of soft-soft and hard-soft correlations set by relative strengths of observed 2P correlations
True 3P Correlations absent True 3P Correlations present
Test of (2+1) removal
(2+1) processes (2+1) processes successfully removed successfully removed
Flat Correlation Surface
(offset added)
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Pairs per trigger from Correlation
Pairs per trigger Input
Pairs/trigger can be calculated from correlation function knowing detected singles and detected triplets
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3-particle Correlations without harmonic removalPHENIX Preliminary
Data
Most central shows jet dominated landscape with strong away side modification
10-20 %0-5 %5-10 %
20-40 %40-60 %60-90 %
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Total 3-particle Jet Correlation
Strong away side modification in both total and true 3P Jet Correlations
Radial section
True 3-particle Jet Correlation
Jet Correlations
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Data
Simulated Deflected jet
Simulated Mach Cone
The data validates the presence of a Mach Cone away-side jet but does not The data validates the presence of a Mach Cone away-side jet but does not rule out contributions from other topologies.rule out contributions from other topologies.
Total 3P jet correlations
True 3P jet correlations
Azimuthal Sections
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Simulated LHC Event
Phi Eta
Et
Phi
Et
Eta
(PYTHIA + HIJING) PYTHIA JetsJetfinder algorithms
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Start Step 1
Step 8 Step 20
PYTHIA Jet
A novel method of jet location in an event has been developed which utilizes successive filtering of soft background
using other events
Soft background
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Expected triplet jet correlation function for Mach flow signal in LHC events
Once hard jet candidates have been identified in a large number of events, the three-particle correlation method can be applied to look for medium modification
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Conclusions
The high pt frame is a suitable choice for the study of jet topology via 3-particle correlations
3-particle jet correlations obtained for 200 GeV Au+Au
3-particle correlation without harmonic removal for most central case shows abnormal jet topology
3-particle Jet correlations show strong away side modification
True 3-particle jet correlations validate presence of Mach Cone jets but do not rule out contributions from other topologies.
Method a potential tool for jet study at the LHC
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N. N. Ajitanand Jyvaskyla 2007 35
Tsunami : Nature’s awesome medium response to a hard event !!