1 Olga Barannikova University of Illinois at Chicago LHC09, Prague Multi-hadron correlations at RHIC...

1Olga Barannikova

University of Illinois at ChicagoLHC09, Prague

Multi-hadron Multi-hadron correlations at RHIC correlations at RHIC and LHCand LHC

Olga Barannikova

2Olga Barannikova

University of Illinois at ChicagoLHC09, PragueLHC09, Prague

OutlineOutline

Jet quenching in heavy ion collisionsEvolution of jet-type correlation analysesTheoretical interpretation of data

Multi-hadron correlations at RHIC

Jets studies via correlations at LHC

Outlook

3Olga Barannikova


Motivation: early resultsMotivation: early results

Signature two-particle correlation result: Disappearance of the away side jet

in central Au+Au collisions Effect vanishes in peripheral/d+Au

collisions

4<pT trig<6 GeV/c 2<pT assoc<pT trigPRL 91 (2003)

072304

PRL 91 (2003)

072303

High pT hadron suppression: Final state effect in Au+Au

collisions Observation extends to all accessible

pT range

4Olga Barannikova


Motivation: higher pMotivation: higher pTT??

4<pT trig<6 GeV/c 2<pT assoc<pT trig

Recovering the away side:• Away-side yield suppression• Little modification of the Near-side yields • No broadening on Near- or Away-sides

d+Au

1/N

trig

dN

/d(

)

Au+Au 20-40% Au+Au 0-5%

8 < pTtrig < 15 GeV/c, pT

assoc>6 GeV/c

PRL 97 (2006) 162301

5Olga Barannikova


High-pHigh-pT T – – vacuum fragmentation?vacuum fragmentation?

Dh1h2 zT ,pTtrig pT

trig d AAh1h2 dpT

trigdpT

d AAh1 dpT

trig

zT pTassoc

pTtrig

Near >

PRL 97 (2006) 162301

Near-side: No dependence on zT in the

measured range – no modification Away side:

Suppression ~ level of RAA

No dependence on zT in the measured range – no modification

6Olga Barannikova


Jet modifications: pJet modifications: pT T

One high-pT, one low-pT trigger Reappearance of the away-side jet Double-hump structure hints at additional

physics phenomena

3<pT trig<4 GeV/c 1.3<pT assoc<1.8GeV/c

M. v Leeuwen,

Hangzhou ‘06

PHENIX

PRL 97, 052301 (2006).

1.0 GeV/c < pT assoc

7Olga Barannikova


Au+Au 0-10%STAR preliminary

Intermediate pIntermediate pT T : the ridge: the ridge

d+Au min. bias

STAR preliminary

3 < pT,trigger < 4 GeV/c

Near-side correlation structure: Central Au+Au: cone-like + ridge-like Strong dependence of cone yield on trigger pT

Week dependence if ridge yield on trigger pT

J. Putschke QM ‘06

8Olga Barannikova


Energy Loss in QCD MediumEnergy Loss in QCD Medium

Double-hump Away-side Long-range Ridge on Same-side

Mach Cone Possible “splash back”

Parton mult. scattering, recombination Chiu, Hwa PRC72:034903,2005

– Radial flow + jet-quenchingS.A.Voloshin, Phys.Lett.B. 632(2006)490 E.Shuryak, hep-ph:0706.3531

Parton + longitudinal flow coupling Armesto et.al PRL93(2004) 242301

…

Quantitative measures energy loss…

Mach ConeStoecker, Nucl. Phys. A750(2005)121Casalderrey-Solana, Shuryak, Teaney, J. Phys. 27(2005)22 Ruppert, B. Muller, PLB 618 (2005)123Renk, Ruppert, PRC 76 (2007) 014908

Parton mult. scattering, recombination Chiu, Hwa, PRC 74(2006) 064909

Radial flow boost + jet quenching Armesto, Salgado, Wiedemann, PRL 93 (2004) 242301

Parton + longitudinal flow coupling

…

9Olga Barannikova


d+Au

Au+Au central

Away side: Away side: -- correlation correlation

nucl-exp:0805.0622

Experimental observation of conical emission = 1.37 ± 0.02 (stat.)± 0.06 (syst.)

Constrains the speed of sound cS ~ 0.2

10Olga Barannikova


Near-side: Near-side: -- correlations correlations

No acceptance

No acceptance

No apparent substructure – no gluon fragments/flow coupling?

No cross-like term – ridge and cone decoupled?

P. Netrakanti QM’08

3<pTTrig<10 GeV/c 1<pT

Asso<3 GeV/c

11Olga Barannikova


Use di-jets to study jet-medium effects “pin” the jet axis selecting back-to-

back triggers study correlation w.r.t. this axis

2+1 Correlation Technique2+1 Correlation Technique

Courtesy of

R .Hollis

“jet-axis”

trigger (T2)

primary

trigger (T1)

associates

associates Raw, uncorrected signal

-1-2 0 1 2 3 4 5

a.u

.

0.6

0.4

0.2

T1: pT>5GeV/c

T2: pT>4GeV/c± 0.2

O.B., QM’08

12Olga Barannikova


Olga BarannikovaUniversity of Illinois at Chicago

2+1 Signal Construction:2+1 Signal Construction:

Raw Correlation Background

Signal

0 - 10% 10-20%

20-30% 30-40%

Flow

T1: pT>5GeV/c

T2: pT>4GeV/c

A: pT>1.5GeV/c-1 0 1 2 3 4 5-2

0.5

0.51.0

1.0

0

STAR Preliminary

Away-side!

Phys. Rev. C72 (2005) 014904

O.B., QM’08

13Olga Barannikova


Correlated Background:Correlated Background:

Signal + Background

Background

Signal

a.u

. T1T2

0 2 4

Accounting for correlated background on T1 and T2 side

Correlated background approximated by di-hadron correlations T2A1, T1A1

2+1 Correlation

-1-2 0 1 2 3 4 5

2

1

0 1

_d

N_

N

trig

d

)

STAR Preliminary

-1-2 0 1 2 3 4 5

2

0 1

_d

N_

Ntr

ig d

)

-2

4

STAR Preliminary

14Olga Barannikova


Di-jets in d+Au 200 GeV Minimum bias data

Slight narrowing of the same-side, big effect for away-side

Difference in yields Di-triggers sample higher

energy jets

Di-jets in d+Au CollisionsDi-jets in d+Au Collisions

T2A1_T1

T2A1

-1-2 0 1 2 3 4 5

1

0

1

_d

N_

Ntr

ig d

) 2

STAR Preliminary

Single trigger

vs.Di-jet trigger

O.B., QM’08

15

LHC09, PragueOlga Barannikova

University of Illinois at Chicago

Di-Jets in Au+Au CollisionsDi-Jets in Au+Au Collisions

Au+Au

d+Au

-1-2 0 1 2 3 4 5

1

0

1

_d

N_

Ntr

ig d

)

STAR Preliminary

2

3

200 GeV Au+Au & d+Au

Central Au+Au ~ d+Au. No away-side suppression! Shapes of near- and away-sides are similar

projection: no significant shape/yield modifications projection: no apparent ridge

O.B., QM’08

Au+Au 12% central

||<0.7

T2A1_T1T1A1_T2

-1-1.5 0 1-0.5 0.5 1.5

1

_d

N_

Ntr

ig d

)

STAR Preliminary

0

200 GeV Au+Au

16Olga Barannikova


Model PredictionsModel Predictions

<E> deposition for back-to-back jets

The energy deposition : T1 , T2 Tune the sensitivity of 2+1 correlations to any medium recoil

T. Rank

PRC75 (2007) 054910

17Olga Barannikova


Monte Carlo studies for LHCMonte Carlo studies for LHC

Generator level study “Generic” HI detector:

Charge hadron tracker

full azimuthal coverage within ||<2.5

pTassoc> 2GeV/c

RHIC-based efficiency/v2

assumptions

10% central Pb+Pb 5.5TeV

HYDJET

Lokhtin et al,hep-ph:0810.2082

18Olga Barannikova


15<pTTrig<20 GeV/c

Mixed Event Background (ZYAM normalization)

Correlation studies with HydjetCorrelation studies with Hydjet

Can compare UNQUENCHED and QUENCHED mode

Raw Signal

a. u

.

HYDJET

Lokhtin et al,hep-ph:0810.2082

19Olga Barannikova


Unquenched Hydjet

Jet yields and energy measurementsJet yields and energy measurements

Jet-energy measurements via associated hadrons

pT in the correlation peak

Jet-multiplicity measurementsSensitivity to quenching?

Lower pT?

V. Chetluru

QM’08

20Olga Barannikova


Summary &Outlook:Summary &Outlook: Medium-induced jet modifications

Double-hump away side Ridge

Differential studies are afforded by multi-particle correlation techniques 3particle - consistent with mach cone 3 particle - no substructure in ridge

Change fragmentation/surface bias with di-jet triggers 2+1 correlations – unmodified di-jet observation Au+Au ~d+Au

Potent tool for the LHC

4-7 February 2009

21Olga Barannikova


Back-UpBack-Up

22Olga Barannikova


One high-pT trigger (only) Away-side modification

• Mono-jets?

• Energy loss for away-side jet?

Di-jet trigger No modification on away-side

• Surface dominated?

• No energy loss for di-jets?

Preliminary Results:Preliminary Results:

T1: pT>5GeV/c

T2: pT>4GeV/c

A: pT>1.5GeV/c

T2A1

T2A1_T1

-1-2 0 1 2 3 4 5

2

0 1

_d

N_

Ntr

ig d

)

-2

4

STAR Preliminary

23Olga Barannikova


4-7 February 2009

STAR Preliminary **

Surface EffectsSurface Effects

T1: pT>5GeV/c

T2: pT>4GeV/c

A: pT>1.5GeV/c

If the triggers have tangential bias: expect a term related to the surface

Surface ~ R2 ~ Npart2/3

** Shown are statistical errors only

Number of triggers per event (per number of binary collisions)

Single triggers and (all qualified) pairs behave similar to inclusives

STAR Preliminary **

T1= 5 GeV/c

1000 200 300 Npart

0

N

trig__

Nev

t Np

art

2/3

0.4

d+Au

x10 -3

STAR Preliminary **

#T1T2 pairs / #Single triggers

#Di-Jets / #Single triggers

1000 200 300

0.015

0.05

0.01

Npart

24Olga Barannikova

University of Illinois at ChicagoLHC09, Prague 24

October 6-10, 2008

3-particle correlation in 3-particle correlation in A1A2

T : Trigger particleA1: First Associated particleA2: Second Associated particle

Jet fragmentation in vacuum

In medium radiation + Longitudinal flow

Transverse flow boost

N.Armesto et.al Phys.Rev.Lett.93(2004) 242301

S.A.Voloshin, Phys.Lett.B. 632(2006)490E.Shuryak, hep-ph:0706.3531

STAR TPC acceptance for3-particle correlation in (||<1 and full azimuth)

Turbulent color field. Momentum Kick C.Y. Wong hep-ph:0712.3282A.Majumder et.al

Phys. Rev. Lett.99(2004)042301

1 Olga Barannikova University of Illinois at Chicago LHC09, Prague Multi-hadron correlations at RHIC...

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