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Jet Correlations. Mike Miller (Yale University). Why Jets?. k T : “Radiative Corrections” pre- and post-scattering di-jet: . In QCD Medium Additional k T Significant energy loss? high p T suppression Sensitive to color properties of medium. “So, why jets?”. - PowerPoint PPT Presentation
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Jet CorrelationsJet Correlations
Mike Miller (Yale University)Mike Miller (Yale University)
2Mike Miller January 2004
In QCD Medium Additional kT
Significant energy loss? high pT suppression
Sensitive to color Sensitive to color properties of mediumproperties of medium
“So, why jets?”
coneRWhy Jets?
Hard probeearly time Calculable: pQCD Abundant at RHIC, LHC
kT: “Radiative Corrections”
pre- and post-scattering di-jet:
Fragmentation:
z hadron
parton
p
p
3Mike Miller January 2004
Moment Analysis of QCD MatterconeR 2 ( )
( )
T g
g
k x dx
E x x dx
I. Vitev, nucl-th/0308028
Induced Gluon Radiation ~collinear gluons in cone “Softened” fragmentation
in je
i j t
t
n e
: increases
z : decreases
chn
Gyulassy et al., nucl-th/0302077
Fragmentation:
z hadron
parton
p
p
4Mike Miller January 2004
Partonic vs. Hadronic MechanismsHottest Questions:
Fragment inside/outside of medium?
Partonic vs. hadronic model of Final State interaction?
coneR
A Better Question: To what degree do partonic
and hadronic interactions contribute to quenching?
Discussion only recently started!
Fragmentation:
z hadron
parton
p
p
5Mike Miller January 2004
4 Ways to “Skin a Cat Jet”
1) Integral Distributions:<pT>, <Nch>
2) Single Particle Spectra:d/dpT RAA, RdA
3) 2-Particle Correlations:dN/d()
4) Jet Reconstruction:d/dET, Frag. Func.
trigger
“Trigger” = 0
Adler et al., PRL90:082302 (2003), STAR
near-side
away-side
6Mike Miller January 2004
, 200 GeVNNAu Au s
Disappearance of the away-sideDisappearance (at mid-rapidity) is dominated Disappearance (at mid-rapidity) is dominated by final state effect(s)!by final state effect(s)! Jet Quenching Jet Quenching
Adams et al., Phys. Rev. Let. 91 (2003)Adler et al., PRL90:082302 (2003), STAR
1/N
trig
gerd
N/d
()
Background subtracted
2nd order correlations due to elliptic flow of entire eventcompeting background
p+p2-jets
Peripheral Au+Au2-jets
Central Au+Au? 1-jet!1-jet!
Near side jet “identical” ppdAuAuAu
d+Au2-jets
di-hadron
7Mike Miller January 2004
Questions Raised at QM02
Initial state effects?
What should 2-particle correlation look like?
Partonic/nuclear kT
jT
Measurable at SPS?
Final state energy loss?
Baryons vs. Mesons?
PID?
Background subtraction?
Jets correlated with reaction plane?
And many more…
This talkThis talk Discussed in parallelDiscussed in parallel
8Mike Miller January 2004
Suppression larger out-of-plane
Path Length Dependence
nGLVE L
di-hadron, 20-60% Central Background SubtractedSee J. Bielcikova et al., (nucl-ex/0311007) for background derivation
STAR Preliminary
s =200 GeVNN
Measured
Reflected
K. Filimonov DNP03
In-plane
Out-of-plane
9Mike Miller January 2004
2.5 4 GeV/c
1 2.5 GeV/c
trigT
assocT
p
p
Path Length Dependence
nGLVE L
Quenching: Consistent with path length DependenceQuenching: Consistent with path length Dependence
di-hadron, 20-40% Central Background SubtractedSee J. Bielcikova et al., (nucl-ex/0311007) for background derivation
In-plane
Out-of-plane
10Mike Miller January 2004
hadron
hadron
Δφ
Jet Fragmentation: “Shape”
Reconstructed jets
sinhadronT T jet hadj p
-sinjetT T jet jetk p
di-hadron
2 2Fa
TTy Near r
pk
z
sin Nearyj p
Jet “width”
Jet-coplanarity
: of colliding
partons
a b
Ty T Tk p p����������������������������Tk
: of hadron to jet axis
Ty Tj p
Tj
parton
parton
11Mike Miller January 2004
kT, jT at RHIC from p+p Data
J. Rak, Wed.
J. Rak, DNP03
s=200 GeV
di-hadron
Statistical Errors Only
near-side away-side
nearfar
12Mike Miller January 2004
kT, jT at RHIC from p+p DataStatistical Errors Only
PHENIX preliminary
|jTy| = 35911 MeV/c
|kTy| = 96449 MeV/c
PHENIX preliminary
|jTy| = 35911 MeV/c
|kTy| = 96449 MeV/c
kT, jT from p+p, d+Au, Au+Au from “0”-hadron, di-hadron, jet, di-jet
Friday:Friday: Completing the reference measurements!Completing the reference measurements!
J. Rak, DNP03
s=200 GeV
Good agreement with previous measurements: PLB97 (1980)163 PRD 59 (1999) 074007
di-hadron
0
p+pd+Au
di-jet
STAR PreliminaryT. Henry, Fri.
10 GeVjetTE
13Mike Miller January 2004
s =200 GeV, Au+AuNN di-hadron correlations
<|jTy|>=400 MeV
-n
ear
-nea
rAu+Au near-side: Jet-like at all centralities?
Follows fragmentation prediction:
1sinTy
T
j
p
Yes, but… widens in
(see c07)
14Mike Miller January 2004
Quenching at SPS?charged-pion pairs
pT>1.2 GeV/c
, 158 A GeV/cPb Au
Accepted by PRL, nucl-ex/0303014, CERES
Near angle correlations:Near angle correlations: Present at all centralitiesConsistent with fragmentation
Away side correlations:Away side correlations:Present at all centralitiesWidth broadens with centrality
mid-central
central
width yield
+ WA98 Spectra: R+ WA98 Spectra: RAAAA>1 >1
See See p36p36
No, but…No, but…Broadening at RHIC!Broadening at RHIC!
15Mike Miller January 2004
Quenching at SPS?
Where is the enhancement at RHIC?Where is the enhancement at RHIC?
16Mike Miller January 2004
Di-Hadrons at “all” pT
See F. Wang, Fri. QM04
< 0.15 < GeV/c assoc trigT Tp p
+ mixed event background subtraction
+ elliptic flow background subtraction
Study “fragmentation” in p+p, Au+AuFull range in pT
Transport from high-pT to low-pT?Change in jet “size”?
Study Study ppTT distribution in near- distribution in near-
and away-side jet conesand away-side jet cones
di-hadron correlations4 6 GeV/ctrig
Tp
1.1
17Mike Miller January 2004
Di-Hadrons at “all” pT
Near-Side Away-Side
s =200 GeVNN
F. Wang, DNP03
0 1 2 3 4(GeV/c)Tp
0 1 2 3 4
STAR Preliminaryp+p40-80% Au+Au0-5% Au+Au
di-hadron correlations
See F. Wang Friday
4 6 GeV/ctrigTp
18Mike Miller January 2004
pT Distribution in Near-Side Jet
Near-Side
s =200 GeVNN
Au
Au
/pp
0 1 2 3 4(GeV/c)Tp
0 1 2 3 4
F. Wang, DNP03
STAR Preliminary
ratio
p+p40-80% Au+Au0-5% Au+Au
di-hadron correlations
Near-SideNear-Side0-5% / pp 0-5% / pp 2 2
40-80% / pp 40-80% / pp 1.2 1.2““enhancementenhancement””
See F. Wang Friday
4 6 GeV/ctrigTp
19Mike Miller January 2004
pT Distribution in Away-Side Jet
Near-Side Away-Side
s =200 GeVNN
Au
Au
/pp
0 1 2 3 4(GeV/c)Tp
0 1 2 3 4
F. Wang, DNP03
ratio ratio
STAR Preliminaryp+p40-80% Au+Au0-5% Au+Au
See F. Wang Friday
di-hadron correlations
suppressed
enhanced
Away-Side (Away-Side (ppTT>2)>2)
AuAu/pp <1AuAu/pp <1““Disappearance”Disappearance”
Away-Side (Away-Side (ppTT<2)<2)
AuAu/pp >1AuAu/pp >1““Enhancement!Enhancement!””
Near-SideNear-Side0-5% / pp 0-5% / pp 2 2
40-80% / pp 40-80% / pp 1.2 1.2““enhancementenhancement””
4 6 GeV/ctrigTp
20Mike Miller January 2004
Au+Au 0-5%
(1/N
trig)
dN/d
()
STAR Preliminary
p+p trig4 6 GeV/c
0.2 4 GeV/c
T
assocT
p
p
Background subtracted Background subtracted
Away-side looks jet-like in p+p, not central Au+Au!Away-side looks jet-like in p+p, not central Au+Au!
So what’s going on?So what’s going on?
Is The Away-Side Jet-Like?
See F. Wang Friday
21Mike Miller January 2004
Is The Away-Side Jet-Like?
Au+Au 0-5%
(1/N
trig)
dN/d
()
STAR Preliminary
p+p
Fit to near side: const. + gaussian + Borghini-cos(fixed)trig4 6 GeV/c
0.2 4 GeV/c
T
assocT
p
p
Background subtracted Background subtractedstat. mom.conserv.stat. mom. conserv.
free fit
2 21 2, cosmeasuredT
total
C p p dpN
N
����������������������������
1~ 10
Amplitude:Amplitude: -Depends on -Depends on ppTT “window” “window”
-Can be tested-Can be tested-Work in progress-Work in progress(see )(see )
Momentum conservation: 1 22 1 2 2
cos, 2 T T
total T
p pC p p
N p
����������������������������Borghini et al., nucl-th/0004026
See F. Wang Friday
22Mike Miller January 2004
What could this mean?
Au+Au 0-5%
(1/N
trig)
dN/d
()
STAR Preliminary
p+p
Fit to near side: const. + gaussian + Borghini-cos(fixed)trig4 6 GeV/c
0.2 4 GeV/c
T
assocT
p
p
Background subtracted Background subtractedstat. mom.conserv.stat. mom. conserv.
free fit
Pessimist:Pessimist:A fundamentally boring A fundamentally boring result…result…AnotherAnother background background
Optimist:Optimist:Maybe the most exciting Maybe the most exciting result yet!result yet!
Away-side energy re-distributed over many particles, broad in Away-side energy re-distributed over many particles, broad in angle, angle, but it is still there!but it is still there!
See F. Wang Friday
23Mike Miller January 2004
Conclusions2-particle correlations
Successful measure of hard-scattering, fragmentation
Away-side quenching in central Au+AuIndicative of strong final state interactionsIn/out-of plane consistent with path length dependence
Semi-hard scattering at SPSPresent at all centralitiesLarge away-side broadening
Near-side correlations in Au+AuConsistent with fragmentation at all centralities
pT distribution in near- and away-side jet conesConsistent with modified fragmentation?
24Mike Miller January 2004
The Real Conclusions
2-particle correlationsRobust jet probe from p+p to central Au+Au
QM02Disappearance of away-side jet
QM04Finding the “lost-energy” on the away-side
Qualitative consistency between PHENIX and STAR
“Transport” from high pT low pT
But… away-side has lost jet-like shape!
25Mike Miller January 2004
Future Directions at RHIC
Minimize ambiguities, sensitivitiesHigher trigger pT only jet production
higher trigger pT smaller kT effects
Higher statistics test of path length dependence
Away-side pT “transport”d+Au?
Trigger-pT dependence?Punch through above momentum conservation?
Calibrate the jet-energy scale: photon-jetMass effect: heavy quarks vs. light quarks EColor charge: quark vs. gluon jets?
26Mike Miller January 2004
Old…
27Mike Miller January 2004
Back side correlations between charged hadrons:Back side correlations between charged hadrons:1/N
trigger*dN/d(∆Φ)
1/N
trigger*dN/d(∆Φ)
1/N
trigger*dN/d(∆Φ)
1/N
trigger*dN/d(∆Φ)
∆Φ (radians)
∆Φ (radians)∆Φ (radians)
∆Φ (radians)
3.7 GeV < P3.7 GeV < PT T trigger trigger <4.5 GeV<4.5 GeV
2.5 GeV < P2.5 GeV < PT T associated associated <3.7 GeV<3.7 GeV
4.5 GeV < P4.5 GeV < PT T trigger trigger <5.4 GeV<5.4 GeV
2.5 GeV < P2.5 GeV < PT T associated associated <3.7 GeV<3.7 GeV
6.5 GeV < P6.5 GeV < PT T trigger trigger <10 GeV<10 GeV
2.5 GeV < P2.5 GeV < PT T associated associated <3.7 GeV<3.7 GeV
5.4 GeV < P5.4 GeV < PT T trigger trigger <6.5 GeV<6.5 GeV
2.5 GeV < P2.5 GeV < PT T associated associated <3.7 GeV<3.7 GeV
Fig. 11 Charged Hadrons correlations for different trigger PFig. 11 Charged Hadrons correlations for different trigger PTT rangerange
Fig. 12 Same side and back Fig. 12 Same side and back side as function of Trigger Pside as function of Trigger PTT
same side is calculated by integrating the Gaussian component and the back side is calculated by integrated the cosine component. Notices that there is a back side signal for the higher PT correlation
Trigger PT
)cos(2
)( cos2
)(
1
2
2
C
BGeCD
Fitting Function:
Trigger PT
In Fig.13. The fitting Ccos is compared to estimation due to the momentum conservation[6].
Fig. 13Fig. 13
28Mike Miller January 2004
In-plane
Out-of-plane
Path Length Dependence
nGLVE L
Quenching: Consistent with path length Dependence!Quenching: Consistent with path length Dependence!
di-hadron, 20-60% Central Background SubtractedSee J. Bielcikova et al., (nucl-ex/0311007) for background derivation
Suppression larger out-of-plane
STAR Preliminary
s =200 GeVNN
Measured
Reflected
K. Filimonov DNP03
29Mike Miller January 2004
In-plane
Out-of-plane
Path Length Dependence
nGLVE L
Quenching: Consistent with path length Dependence!Quenching: Consistent with path length Dependence!
di-hadron, 20-60% Central Background SubtractedSee J. Bielcikova et al., (nucl-ex/0311007) for background derivation
Suppression larger out-of-plane
STAR Preliminary
s =200 GeVNN
Measured
Reflected
K. Filimonov DNP03
30Mike Miller January 2004
Away-Side Quenching (2002)
Adler et al., PRL90:082302 (2003), STAR
Background subtracted
, 200 GeVNNAu Au s 2nd order correlations due to elliptic flow of entire eventcompeting background
1/N
trig
gerd
N/d
()p+p
2-jetsPeripheral Au+Au
2-jetsCentral Au+Au
? 1-jet!1-jet!
di-hadron
31Mike Miller January 2004
Away-Side Quenching (2002)
Adler et al., PRL90:082302 (2003), STAR
Background subtracted
, 200 GeVNNAu Au s 2nd order correlations due to elliptic flow of entire eventcompeting background
1/N
trig
gerd
N/d
()p+p
2-jetsPeripheral Au+Au
2-jetsCentral Au+Au
? 1-jet!1-jet!
di-hadron
32Mike Miller January 2004
Conclusions2-particle correlations
Successful measure of hard-scattering, fragmentation
Jet-like correlations at all centralities in Au+Au
Away-side correlationspT distribution in near- and away-side jet cones
Consistent with modified fragmentation?
33Mike Miller January 2004
Unraveling final state mechanisms at RHIC
Minimize ambiguities, sensitivitiesHigher trigger pT only jet production
higher trigger pT smaller kT effects
Higher statistics test of path length dependence
Away-side pT “transport”d+Au?
Trigger-pT dependence?Punch through above momentum conservation?
Calibrate the jet-energy scale: photon-jetMass effect: heavy quarks vs. light quarks EColor charge: quark vs. gluon jets?