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1 Olga Barannikova University of Illinois at Chicago LHC09, Prague Multi-hadron correlations at RHIC and LHC Olga Barannikova
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2 University of Illinois at Chicago LHC09, Prague Outline Jet quenching in heavy ion collisions Evolution of jet-type correlation analyses Theoretical interpretation of data Multi-hadron correlations at RHIC Jets studies via correlations at LHC Outlook
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3 Olga Barannikova University of Illinois at Chicago LHC09, Prague Motivation: 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<p T trig <6 GeV/c 2<p T assoc <p T trig PRL 91 (2003) 072304 PRL 91 (2003) 072303 High p T hadron suppression: Final state effect in Au+Au collisions Observation extends to all accessible p T range
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4 Olga Barannikova University of Illinois at Chicago LHC09, Prague Motivation: higher p T ? 4<p T trig <6 GeV/c 2<p T assoc <p T 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 6 GeV/c PRL 97 (2006) 162301
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5 Olga Barannikova University of Illinois at Chicago LHC09, Prague High-p T – vacuum fragmentation? Near> PRL 97 (2006) 162301 Near-side: No dependence on z T in the measured range – no modification Away side: Suppression ~ level of R AA No dependence on z T in the measured range – no modification
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6 Olga Barannikova University of Illinois at Chicago LHC09, Prague Jet modifications: p T One high-p T, one low-p T trigger Reappearance of the away-side jet Double-hump structure hints at additional physics phenomena 3<p T trig <4 GeV/c 1.3<p T assoc <1.8GeV/c M. v Leeuwen, Hangzhou ‘06 PHENIX PRL 97, 052301 (2006). 1.0 GeV/c < p T assoc
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7 Olga Barannikova University of Illinois at Chicago LHC09, Prague Au+Au 0-10% STAR preliminary Intermediate p T : the ridge d+Au min. bias STAR preliminary 3 < p T,trigger < 4 GeV/c Near-side correlation structure: Central Au+Au: cone-like + ridge-like Strong dependence of cone yield on trigger p T Week dependence if ridge yield on trigger p T J. Putschke QM ‘06
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8 Olga Barannikova University of Illinois at Chicago LHC09, Prague Energy 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-quenching S.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 Cone Stoecker, Nucl. Phys. A750(2005)121 Casalderrey-Solana, Shuryak, Teaney, J. Phys. 27(2005)22 Ruppert, B. Muller, PLB 618 (2005)123 Renk, 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 …
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9 Olga Barannikova University of Illinois at Chicago LHC09, Prague d+Au Au+Au central Away side: - correlation nucl-exp:0805.0622 Experimental observation of conical emission = 1.37 ± 0.02 (stat.)± 0.06 (syst.) Constrains the speed of sound c S ~ 0.2
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10 Olga Barannikova University of Illinois at Chicago LHC09, Prague Near-side: - correlations No acceptance No apparent substructure – no gluon fragments/flow coupling? No cross-like term – ridge and cone decoupled? P. Netrakanti QM’08 3<p T Trig <10 GeV/c 1<p T Asso <3 GeV/c
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11 Olga Barannikova University of Illinois at Chicago LHC09, Prague 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 Technique Courtesy of R.Hollis “jet-axis” trigger (T2) primary trigger (T1) associates Raw, uncorrected signal -2 01 2 345 a.u. 0.6 0.4 0.2 T1: p T >5GeV/c T2: p T >4GeV/c ± 0.2 O.B., QM’08
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12 Olga Barannikova University of Illinois at Chicago LHC09, Prague Olga Barannikova University of Illinois at Chicago 2+1 Signal Construction: Raw Correlation Background Signal 0 - 10% 10- 20% 20-30% 30- 40% Flow T1: p T >5GeV/c T2: p T >4GeV/c A: p T >1.5GeV/c 01 2 3 45 -2 0.5 1.0 0 STAR Preliminary Away-side! Phys. Rev. C72 (2005) 014904 O.B., QM’08
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13 Olga Barannikova University of Illinois at Chicago LHC09, Prague 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 -2 01 2 345 2 1 0 1 _dN_ N trig d ) STAR Preliminary -2 01 2 345 2 0 1 _dN_ N trig d ) -2 4 STAR Preliminary
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14 Olga Barannikova University of Illinois at Chicago LHC09, Prague 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 Collisions T2A1_T1 T2A1 -2 01 2 345 1 0 1 _dN_ N trig d ) 2 STAR Preliminary Single trigger vs. Di-jet trigger O.B., QM’08
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15 LHC09, Prague Olga Barannikova University of Illinois at Chicago Di-Jets in Au+Au Collisions Au+Au d+Au -2 01 2 345 1 0 1 _dN_ N trig 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_T1 T1A1_T2 -1.5 0 1 -0.5 0.5 1.5 1 _dN_ N trig d ) STAR Preliminary 0 200 GeV Au+Au
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16 Olga Barannikova University of Illinois at Chicago LHC09, Prague Model Predictions 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
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17 Olga Barannikova University of Illinois at Chicago LHC09, Prague Monte Carlo studies for LHC Generator level study “Generic” HI detector: Charge hadron tracker full azimuthal coverage within | |<2.5 p T assoc > 2GeV/c RHIC-based efficiency/v 2 assumptions 10% central Pb+Pb 5.5TeV HYDJET Lokhtin et al, hep-ph:0810.2082
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18 Olga Barannikova University of Illinois at Chicago LHC09, Prague 15<p T Trig <20 GeV/c Mixed Event Background (ZYAM normalization) Correlation studies with Hydjet Can compare UNQUENCHED and QUENCHED mode Raw Signal a. u. HYDJET Lokhtin et al, hep-ph:0810.2082
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19 Olga Barannikova University of Illinois at Chicago LHC09, Prague Unquenched Hydjet Jet yields and energy measurements Jet-energy measurements via associated hadrons p T in the correlation peak Jet-multiplicity measurements Sensitivity to quenching? Lower p T ? V. Chetluru QM’08
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20 Olga Barannikova University of Illinois at Chicago LHC09, Prague 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
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21 Olga Barannikova University of Illinois at Chicago LHC09, Prague Back-Up
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22 Olga Barannikova University of Illinois at Chicago LHC09, Prague One high-p T 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: T1: p T >5GeV/c T2: p T >4GeV/c A: p T >1.5GeV/c T2A1 T2A1_T1 -2 01 2 345 2 0 1 _dN_ N trig d ) -2 4 STAR Preliminary
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23 Olga Barannikova University of Illinois at Chicago LHC09, Prague 4-7 February 2009 STAR Preliminary ** Surface Effects T1: p T >5GeV/c T2: p T >4GeV/c A: p T >1.5GeV/c If the triggers have tangential bias: expect a term related to the surface Surface ~ R 2 ~ N part 2/3 ** 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 100 0 200 300 N part 0 N trig __ N evt N part 2/3 0.4 d+Au x 10 -3 STAR Preliminary ** #T1T2 pairs / #Single triggers #Di-Jets / #Single triggers 100 0 200 300 0.015 0.05 0.01 N part
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24 Olga Barannikova University of Illinois at Chicago LHC09, Prague 24 October 6-10, 2008 3-particle correlation in A1 A2 T : Trigger particle A1: First Associated particle A2: 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)490 E.Shuryak, hep-ph:0706.3531 STAR TPC acceptance for 3-particle correlation in (| |<1 and full azimuth) Turbulent color field. Momentum Kick C.Y. Wong hep-ph:0712.3282 A.Majumder et.al Phys. Rev. Lett.99(2004)042301
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