An overview of high-pT correlations at SPS and RHIC
Mateusz Płoskoń
24th of March 2007 High-pT at LHC 2
RAA at SPS and RHIC
p+W @ s = 19.4GeV
dNg/dy = 400-600 + Cronin + shadowingI. Vitev and M. Gyulassy, PRL 89 (2002), 252301
C. Blume
Nucl. Phys. A 783 (2007)
Energy density at s = 17.3 GeV: 0 3GeV/fm3
SPSSPS Direct photons scale with NDirect photons scale with Nbinbin
High-pHigh-pT T hadrons are suppressedhadrons are suppressed
At SPS: At SPS: Interplay between Cronin Interplay between Cronin enhancement and possibleenhancement and possible
jet quenching effectsjet quenching effects
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STAR, Phys Rev Lett 91, 072304
Azimuthal Correlationstrigger
associate 1
associate 2
parton 1
parton 2
1
2
near side
away side
Medium(?)
A+A
p+p
4 < pt,trig < 6 GeV and pt,assoc > 2 GeV
In A+A collisions away-side structure In A+A collisions away-side structure modified due to interaction with the mediummodified due to interaction with the medium
Two-particle correlations
at SPS
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2 Silicon Drift (SiDC) detectors, 2 RICH detectors, TPC : p/p = ((2%)2 + (1% p (GeV/c)2)1/2
Acceptance: 8o < < 15o (2.1 < < 2.65), full azimuthData set: 30 mln Pb+Au events (year 2000 run)Centrality selection: 5%, 5-10%, 10-20% most central
CERES Spectrometer with the TPC
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Pioneering plots: 2-pion azimuthal correlation- pre-TPC CERES analysisTwo-particle azimuthal correlations of pions with pT > 1.2 GeV/c - centrality dependent.
CERES Collaboration, G. Agakichev, et al. Phys. Rev. Lett. 92 (2004) 032301
21 - 26 %
J. Bielcikova, PhD thesis Prague/Heidelberg 2003
< 6.16.1 - 10.6 %
10.6 - 15.1 %15.1 - 19.3 %
19.3 - 24.2 %24.2 - 30.0 %
9 - 13 %The full line - Gaussian fits to semi-hard components on top of elliptic flow modulated background (dashed line)
Broadening of the away-side component with centrality
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Procedure (PHENIX: nucl-ex/0507004):
1. Accumulate: YAB()=A-B (A != B)
2. Accumulate: Ymixed()=A-Cmixed
3. Divide normalized yields:
4. Assume:
5. Fix (C0) and subtract the flow (ZeroYieldAtMinimum(*))6. Normalize and extract J
- jet associated particles(pairs) per trigger
)()(
)()(
d
dN
dY
dY
Y
YC
AB
same
mixed
mixed
same
)()cos(21)( 220 JvvCC BA
A
ABABJetDi
trig N
N
dC
J
d
dN
N
)()´(
)(
)(
1 )(
NA – number of triggersNAB – pairsAssuming AB=AB the trigger efficiency cancels out
Azimuthal angular 2-particle correlations - the recipe
mrad10min
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A Monte Carlo exampleLets generate:- a trigger jet at = 0- scattered jet (left or right) at = - on top of flow
SIMULATION
A note on the ZYAM condition
The di-jet yield is nowhere ZERO
ZYAM condition may overestimatethe background contribution in caseswhere the (di-)jet yields/widths overlap
JET-T
JET-A
JET-Bdifferent event
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2-particle correlations from Pb+Au at 158 GeV/cAll charged particles with 1.0 < pT
assoc < 2.5 < pTtrigg < 4.0 GeV/c
Flow (v2) from the reaction plane analysis: nucl-ex/0510057 and refs there
Strongly modified away-side in near central collisions as compared to a (expected) Gaussian-like shape. Modifications centrality dependent.
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Trigger-associated charge selection
Normalized to the total number of triggers (no charge selection)
All charged with 1.0 < pTassoc < 2.5 < pT
trigg < 4.0 GeV/c
Indication (near-side) for charge ordering in the fragmentation process.“Reversed yields” on the away side – correlated (di-)fragmentations(?) – global-di-jet charge conservation(?).
MP
, Nuc
l. P
hys.
A 7
83 (
2007
)
STAR 200 GeV/cSTAR 200 GeV/c
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Charge-charge correlations - unfolded /geom = 0 - 5 %
S. Kniegenucl-ex/0703008
Independent of the trigger yield is dominated by the positive particles (in the fragmentation constrained to the pT-associated range) – PYTHIA calculations indicate isospin effects – not observed at RHIC nor at LHC.
localminimum ?
CERES data: Pb+Au at 158 GeV/c
Selected correlations at RHIC
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Medium on the near side ?STAR preliminary 0-10% Au+Au3 < pt,trigger < 4 GeV, pt,assoc. > 2 GeV
Jet spectra
Yie
ld (
pt,
ass
oc
> p
t,as
so
c,c
ut)
pt,assoc,cut
inclusive
STAR preliminary
Ridge spectra
Yie
ld (
pt,
ass
oc
> p
t,as
so
c,c
ut)
pt,assoc,cut
inclusive
STAR preliminary
Radiated gluons, broadened byLongitudinal flow, Armesto et al, PRL 93 (2004) QCD magnetic fields, Majumder et al, hep-ph/0611035Anisotropic plasma, P. Romantschke, PRC,75014901 (2007)
Medium heating + recombinationChiu & Hwa, PRC72, 034903
Radial flow + trigger bias S. Voloshin, nucl-th/0312065, Nucl. Phys. A749, 287
Unfortunately not accessible at SPS experiments due to limited Unfortunately not accessible at SPS experiments due to limited acceptance) acceptance)
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Away-side at RHIC
STAR, Phys Rev Lett 95, 152301
pTtrigger>8 GeV/c
Yie
ld p
er tr
igge
r
STAR, nucl-ex/0604018
PHENIX, QM05 and nucl-ex/0507004
Shape evolving Shape evolving with centralitywith centrality
Away-side pAway-side pTT evolution: evolution:Clear narrow peak:Clear narrow peak:
Punch throughPunch throughFlat:Flat:
Jet quenching – meltingJet quenching – meltingDouble-peak structure:Double-peak structure:
Mach cones shock wavesMach cones shock waves+ more…+ more…
Broad cosine-like structure:Broad cosine-like structure:thermalized gluons thermalized gluons + momentum conservation+ momentum conservation
Low-pLow-pTT
High-pHigh-pTT
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Similar pT at RHIC… and SPS
PHENIX Au+Au at sqrt(s) = 200 GeV/c
1.0 < pTassoc < 2.5 < pTtrigg < 4.0 GeV/c
PHENIX, nucl-ex/0507004 nucl-ex/0511048
Au+Au at 62.4 GeV/c
Similar away-side structure (AND) evolving with centrality…… similar mechanism(s) at work at RHIC and SPS?
CERES Pb+Au at sqrt(s) = 17.32 GeV/c
nucl-ex/0511043
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Possible scenarios for the origin of the modified away-side
Double peak structure arising from Mach cone shock waves:H. Stöcker, Nucl. Phys. A 750, 121 (2005),J. Casalderrey-Solana, E. V. Shuryak and D. Teaney, Nucl. Phys. A 774, 577-580 (2006).
Induced gluon radiation:I. Vitev, Phys. Lett. B 630, 78 (2005).
Cherenkov-like radiation:V. Koch, A. Majumder and X.-N. Wang, Phys. Rev. Lett. 96, 172302 (2006).
Medium-induced radiative energy loss:A. D. Polosa, C. A. Salgado hep-ph/0607295
?
Punch-throughPossible broadening
Strongly non-GaussianModified shapes
T. RenkT. RenkK.J. EskolaK.J. EskolaJ. RuppertJ. Ruppert
QM´06QM´06
0-5%0-5%5-10%5-10%
??
0-5%0-5%5-10%5-10%10-20%10-20%
??
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Hydrodynamical Study of Jet Energy Loss
t = 0 fm/ct = 0 fm/cMedium Medium
in the mixed phasein the mixed phase
EoS with 1st order phase transitionEoS with 1st order phase transition
masseless QGP: cmasseless QGP: css ~ 0.57 ~ 0.57 θ = 1.0 radθ = 1.0 rad hadronic matter: chadronic matter: css ~ 0.3 ~ 0.3
11stst order phase transition: c order phase transition: css ~ 0 ~ 0
θ = 1.3 radθ = 1.3 rad
θ = 1.5 radθ = 1.5 rad
• vvjetjet depends on the mass of the leading quarks depends on the mass of the leading quarks
F. Wang, QM06
Emission Angle of the Mach ConesEmission Angle of the Mach Cones
cos θ = cs / vjet ~ 60 – 90 deg
B. Betz, Talk at DPG 2007B. Betz, Talk at DPG [email protected]@th.physik.uni-frankfurt.de
t = 12.8 fm/ct = 12.8 fm/c
Three-particle correlations
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Considering different scenarios with Monte Carlo Jets
Di-jet correlation function – generated jets:• exactly back-to-back• smeared away side (randomized deflection)• away side scattered either left or right• conical away side pattern
• leading to a double peak structure within the same event
Different mechanisms may lead to similar structures in 2-particle correlations. 3-particle correlations provide additional topology information.
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3-particle correlations – studying the jet-jet correlations - an example case
JJJFFFFJFJFJ ))()(())()((
A-T vs B-T
SIMULATION
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Measured 3-particle correlations –
Preliminary resultsRaw correlation function
Reconstructed signal
CERES data: Pb+Au at 158 GeV/c
geom : 7%Trigger pt : (2.5-4.0) GeV/c Associate pt : (1.0-2.5) GeV/c
Subtraction of two particle correlations ( soft*soft , hard*soft )
Similar to
J. G. Ulery and F. Wang nucl-ex/0609016
b=1 (Ulery and Wang)b=1 (Ulery and Wang)No assumption NNo assumption N22
2-part2-part=N=N3-part3-part
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Measured 3-particle correlations –
Preliminary resultsRaw correlation function
Reconstructed signal
Possible topology
Cone-like emission
Possible topology
“Deflection”
CERES data: Pb+Au at 158 GeV/c
geom : (0.0-5.0)%Trigger pt : (2.5-4.0) GeV/c Associate pt : (1.0-2.5) GeV/c
Projection onto 2-part. Projection onto 2-part. rror of the projection (3-part. correl.)rror of the projection (3-part. correl.)not indicated (but >> 0)not indicated (but >> 0)
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3-Particle Correlations - DATAat RHIC and
SPS
CE
RE
SC
ER
ES
STAR preliminarySTAR preliminaryQM’06QM’06
QM’06QM’06
Au+Au 0-12%Au+Au 0-12%
Alongation:Alongation:SPS:no(?)SPS:no(?)RHIC: yesRHIC: yes
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Another method for 3-particle correlations Study angular correlations between the associated particles on the away
side
trigger norm
norm
S ( )
B (C )
)(
associate1 associate2
pt : (1.0-2.5) GeV/c pt : (2.5-4.0)
GeV/c S: trigger and accociates from the same event
B: trigger, accociate1, associate2 from different events
Orientation of angles with respect to the trigger
0°
180°
cut on associate with respect to trigger
trig<->ass> 1.0
trigger
Phase SpacePhase Space
Count angles: 0-360 degCount angles: 0-360 deg
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Monte Carlo studies of the background
flow*flow
flow*jet +flow*flow
data
flow comp.subtracted
•Monte Carlo construction of non jet-jet contributions to the measured data •based on the 2 particle conditional yield and measured elliptic flow.
Yield of away side pairs
a.u.
normalized bysteeply falling
distribution
Indication of cone structure on the away side ? needs further investigation
C(
Preliminary
Preliminary
Preliminary
No trigger separation cut
geom : (0.0-5.0)%
Trigger pt : (2.5-4.0) GeV/c Associate pt : (1.0-2.5) GeV/c
C(
Project the 2D plot into 1D * plot at * that gives maximum correlation at away side
Mach ConeDeflected Jet
* *
PHENIX MC - PHENIX MC - Chun Zhang QM’06
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Sructure on the away side also seen with cut around the trigger region
TA 1.0
a.u.
trigger sep. cut TA>1.0
Yield of away side pairs
TPreliminary
Indication of cone structure on the away side ? needs further investigation
??
24th of March 2007 High-pT at LHC 27
Summary At intermediate pT 2-particle correlations show strong
modifications of the away-side structure as compared to p+p collisions – both at RHIC and SPS
Near- and away-side yields are sensitive to the trigger-associated charge combinations – near side: both at RHIC and SPS – away side: only SPS
Preliminary analysis of the 3-particle correlations indicates possible cone-like emission – further analysis in progress – both at RHIC and SPS… ;)
LHC? : Looking forward for the first data…
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CERES CollaborationD. Adamova, G. Agakichiev, D. Antończyk, A. Andronic, H. Appelshäuser,
V. Belaga, J. Bielcikova, P. Braun-Munzinger, O. Busch, A. Castillo, A. Cherlin, S. Damjanovic, T. Dietel, L. Dietrich, A. Drees, S. Esumi, K. Filimonov, K. Fomenko,
Z. Fraenkel, C. Garabatos, P. Glässel, G. Hering, J. Holeczek, S. Kniege, V. Kushpil, B. Lenkeit, W. Ludolphs, A. Maas, A. Marin, J. Milosevic, A. Milov, D. Miśkowiec, R. Ortega,
Yu. Panebrattsev, O. Petchenova, V. Petracek, A. Pfeiffer, M.Płoskoń, S. Radomski, J. Rak, Ravinovich, P. Rehak, W. Schmitz, J. Schukraft, H. Sako, S. Shimansky,
S. Sedykh, J. Stachel, M. Sumbera, H. Tilsner, I. Tserruya, G. Tsiledakis, T. Wienold, B. Windelband, J.P. Wessels, J.P. Wurm, W. Xie, S. Yurevich, V. Yurevich
NPI ASCR, Rez, Czech RepublicGSI Darmstadt, Germany
Frankfurt University, GermanyHeidelberg University, Germany
JINR Dubna, RussiaWeizmann Institute, Rehovot, Israel
SUNY at Stony Brook, USACERN, SwitzerlandBNL, Upton, USA
Münster University, GermanyMPI Heidelberg, Germany
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PYTHIA and UrQMD testswithin CERES
acceptance
UrQMD – special customized setup(!): Pb+Au @ 160 AGeV, b<5.8fmPythia called for hard-scatterings with Ecm > 10 GeV, short formation time to allow multiple interactions
Standard PYTHIA sqrt(s) = 17.32 GeV2-track resolution cut appliedCeres TPC geometrical acceptance
5% central
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Pythia (red) and UrQMD (blue)
ALL LIKE-SIGN
UNLIKE-SIGN
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3 Particle correlations : two particle contributions
- (..+..+.. ) =
yieldraw correlations
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More MC studies (?)No dip at pi in 2-part. correl.No dip at pi in 2-part. correl.Dip at pi in 2-part. correl. – not data-likeDip at pi in 2-part. correl. – not data-like
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Pure correlation function !!!No flow subtraction , No normalisation
C(
like signall unlike sign
correlations on top of a steeply falling background
(due to orientation of angleswith respect to the trigger)
background
a.u.
(Very) preliminary results
24th of March 2007 High-pT at LHC 34
correlations among the associates
trigger separation cut TA>1.0
no trigger separation cut
all unlike sign like sign
all unlike sign like sign
Trigger pt : (2.5-4.0) GeV/c Associate pt : (1.0-2.5) GeV/c
Preliminary Preliminary
Preliminary Preliminary Preliminary
Preliminary
geom : (0.0-5.0)%
geom : (0.0-5.0)%
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Energy scan – eta +-1
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Energy scan – wide eta
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Data and Pythia and UrQMD
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3-particle correlations – CERES data Limiting factor – statistics:
Example from Au+Au central at RHIC: Typical S/B = 1/30 For 3-particle correl: S/B~10-3
Systematic precision of the order of 10-4
Estimations for SPS: number of particles in the
associated pT range is 10 on average
most of them are from background(!)
S/B is of about 1/150 S/B for 3-particle correlations is
squared!
Only correlation function – no background subtraction
PRELIMINARY
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Transverse momentum spectra
NUCL-EX/0407019
Preliminary
Rapidities 2-2.6Corrected for efficiency only
h_
Measured with TPC-year 2000 data -~7% centralityNo corrections at all
2.1 < < 2-65
Preliminary
Present correlationsstudies :pT 1-4 GeV/c
Mixed event stat. problemNot resolution effect