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Cone is medium response, Ridge is medium itself. Fuqiang Wang Purdue University For the STAR Collaboration
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Plan of talk Away-side cone: medium response to hard probes Near-side ridge: medium response or itself? Bridger ridge, Montana 2Flow and Dissipation Workshop, Trento, Sept. 2009Fuqiang Wang
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The away-side structure 3 p+p Au+Au Flow and Dissipation Workshop, Trento, Sept. 2009Fuqiang Wang PHENIX High p T trigger particle associated particles Away- side trigger jet 0 1
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Possible physics scenarios p T trig =3-4 GeV/c, p T assoc =1-2.5 GeV/c Away-side trigger jet 0 1 trigger jet Mach cone away trigger jet deflected jets away event 1 event 2 Surface bias 4Flow and Dissipation Workshop, Trento, Sept. 2009Fuqiang Wang
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1 = 1 trig 2 0 0 = 2 trig 3-particle azimuthal correlation 1 2 0 0 away trigger jet deflected jets away event 1 event 2 trigger jet Mach cone away signature of conical emission 5Flow and Dissipation Workshop, Trento, Sept. 2009Fuqiang Wang
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Evidence of conical emission d+AuAu+Au central 1 2 0 0 Away-side STAR, PRL 102, 052302 (2009) trigger 6Flow and Dissipation Workshop, Trento, Sept. 2009Fuqiang Wang
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Conical emission angle = 1.37 ± 0.02 (stat.) ± 0.06 (syst.) STAR, PRL 102, 052302 (2009) Away-side trigger Constant cone angle vs p T suggests Mach Cone shock waves may be the underlying mechanism. 7Flow and Dissipation Workshop, Trento, Sept. 2009Fuqiang Wang
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Higher trigger p T 4 < p T trig < 6 GeV/c 1 < p T assoc < 2.5 GeV/c 6 < p T trig < 10 GeV/c 1 < p T assoc < 2.5 GeV/c 1 < p T assoc < 2 GeV/c 8Flow and Dissipation Workshop, Trento, Sept. 2009Fuqiang Wang
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Theory calculations Parton energy loss: Renk et al. PRC 76, 014908 (2007) pQCD + hydro: Neufeld et al. arXiv:0807.2996 quark v = 0.99955 (z - ut) 9Flow and Dissipation Workshop, Trento, Sept. 2009Fuqiang Wang
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AdS/CFT Correspondence N N = 4 Super-Yang-Mills theory in 4d with SU(N C ) Maldacena (1997), Gubser, Klebanov,Polyakov; Witten (1998) YM observables at infinite N C and infinite coupling can be computed using classical gravity. A string theory in 5d AdS Measure heavy quark Mach-cone shock waves: Experimental consequence of string theory? Chesler & Yaffe arXiv:0712.0050 Heavy quark u = 0.75c 10Flow and Dissipation Workshop, Trento, Sept. 2009Fuqiang Wang
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M = 1.37 p HG c S = 0.45 QGP c S = √1/3 = 0.58 Mixed phase c S = 0 Speed of sound? c S far smaller than HG or QGP. Must have mixed phase (phase transition). EOS: p( ) speed of sound c S ~ 0.2 However, model calculations indicate that Mach Cone angle can be altered by medium flow. 11Flow and Dissipation Workshop, Trento, Sept. 2009Fuqiang Wang
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Investigating flow effect on cone angle
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Fit to large azimuthal correlations 2 Gaus: Ridge at 0 and ridge at , same shape, diff. magnitudes 2 Gaus: identical conical emission peaks symmetric about . STAR Preliminary 13Flow and Dissipation Workshop, Trento, Sept. 2009Fuqiang Wang Au+Au 20-60%, 3<p T trig <4, 1<p T trig <2 GeV/c
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Cone angle takes off after trigger s =45 o. Split in p T after s =45 o. Cone angle ~constant over p T at s <45 o. STAR Preliminary 14Flow and Dissipation Workshop, Trento, Sept. 2009Fuqiang Wang
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Is there a back-to-back RIDGE? RP Trig. Ridge Away 2 Away 1 Near Jet Away-Side Ridge 15Flow and Dissipation Workshop, Trento, Sept. 2009Fuqiang Wang
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Connection between near- and away-side Away-side 0 1 STAR Preliminary 16Flow and Dissipation Workshop, Trento, Sept. 2009Fuqiang Wang
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∆φ Separate 1 st and 2 nd quadrants trigger particles Azimuthal correlation for large | |>0.7 Near-side ridge Gauss repeated at “+π” Subtract back-to-back symmetric ridge peaks ∆φ STAR Preliminary 17Flow and Dissipation Workshop, Trento, Sept. 2009Fuqiang Wang
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Away-side asymmetric cone positions Evidence of flow effect on conical emission. Important to disentangle flow effect and conical emission angle. 1 st cone peak 2 nd Cone peak φsφs ∆φ STAR Preliminary RP trigger 2 nd Cone 1 st cone 18Flow and Dissipation Workshop, Trento, Sept. 2009Fuqiang Wang
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trigger particle p T > 3 GeV/c assoc. particle p T =1-2 GeV/c d+Au Au+Au ridge The longitudinal ridge ~ 1 ~ 0 High-p T trigger particle associated particle | |< 0.7 Bridger ridge, Montana 19Flow and Dissipation Workshop, Trento, Sept. 2009Fuqiang Wang
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What’s already known about ridge M. Daugherity (STAR), QM’08, J.Phys.G35:104090,2008 STAR, arXiv:0909.0191 Ridge present in untriggered correlation. Ridge increases with centrality. Ridge pt spectrum is a bit harder than bulk. Ridge particle composition similar to bulk.
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Ridge extended to very large PHOBOS, arXiv:0903.2811 STAR Preliminary 2.7<| |<3.9 p T assoc > 1.0 GeV/c STAR, arXiv:nucl-ex/0701061 21Flow and Dissipation Workshop, Trento, Sept. 2009Fuqiang Wang
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New insights from RP-dependent dihadron correlations
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jet ridge cut to “separate” jet and ridge |∆η|>0.7 = ridge + away-side Jet = (|∆η| 0.7) assuming ridge is uniform in ∆η. Feng, QM’06. STAR Preliminary Au+Au 20-60%, 3<p T trig <4, 1.5<p T trig <2.0 GeV/c d+Au 23Flow and Dissipation Workshop, Trento, Sept. 2009Fuqiang Wang
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Ridge decreases with RP Ridge drops when trigger particle moves away from RP. in-planeout-of-plane trigger | s STAR Preliminary 24Flow and Dissipation Workshop, Trento, Sept. 2009Fuqiang Wang
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A model prediction motivated by data in-plane jet flow aligned more ridge out-of-plane jet flow misaligned less ridge Chiu,Hwa, arXiv:0809.3018 Correlated Emission Model (CEM) Alignment of jet propagation and medium flow produces the ridge. If correct, would produce measureable asymmetry in near-side ridge correlation peak. Correlated Emission Model (CEM) 25Flow and Dissipation Workshop, Trento, Sept. 2009Fuqiang Wang
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Remove away-side from large correlation Ridge Jet Konzer, QM’09. STAR Preliminary |∆η|>0.7 ∆ = assoc – trig Trig. pt=3-4 GeV/c, assoc pt=1-1.5 GeV/c φ s = 0 to -15-15 to -30-30 to -45-45 to -60 -60 to -75 -75 to -90 -1 0 1 π 0.05 0 Au-Au 20-60% ZYAM Jet remains constant Ridge Decreases Jet symmetric Ridge asymmetric 26Flow and Dissipation Workshop, Trento, Sept. 2009Fuqiang Wang
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Correlation Asymmetry in-plane trigger pt=3-4 GeV/c Jet Ridge s |= trig – ψ RP out-of- plane CEM model Ridge: assoc pt=1-1.5 GeV/c Ridge: assoc pt=1.5-2 GeV/c Jet: assoc pt=1.5-2 GeV/c STAR Preliminary Away-side is Asymmetric (not shown in plot). Jet is symmetric. Ridge is Asymmetric! Ridge may be due to jet-flow alignment. v 2 syst. 27Flow and Dissipation Workshop, Trento, Sept. 2009Fuqiang Wang
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New insights from 3-particle - correlation
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How does long come about? Many models on the market. | |<0.7 3<p T trig <10 GeV/c, 1<p T assoc <3 GeV/c d+AuCentral Au+Au Netrakanti, QM’09. arXiv:0907.4744 STAR Preliminary 3-particle - correlations N. Armesto et al., Phys. Rev. Lett. 93 (2004) 242301 Fuqiang WangNucleus-Nucleus 2009, August 200929
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3<p T trig <10 GeV/c 1<p T assoc <3 GeV/c | |<0.7 3-particle - correlations Charge independent (All) AA Like = (AA Like T Like + AA Like T Unlike ) AA Unlike = All - AA Like dAu AuAu 12% STAR Preliminary Netrakanti, QM’09. STAR Preliminary
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Separate jet and ridge Jet has charge ordering ridge does not ridge Same-sign triplets: Only ridge, no jet. jet Netrakanti, QM’09. arXiv:0907.4744. STAR Preliminary
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Ridge is structureless No prominent subtructures in ridge. (jet) = 0.25 0.09 (ridge) = 1.53 0.41 Radial Projection Angular Projection STAR Preliminary Netrakanti, QM’09. arXiv:0907.4744. STAR Preliminary R 32Flow and Dissipation Workshop, Trento, Sept. 2009Fuqiang Wang
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Ridge-jet cross pairs 33 Ridge and jet appear to be anti-correlated. Netrakanti, QM’09. arXiv:0907.4744. STAR Preliminary Fuqiang Wang
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Experimental facts 1)Ridge increases with centrality. 2)Ridge spectrum a bit harder than bulk. 3)Ridge particle composition similar to bulk. 4)Ridge present in untriggered correlation. 5)Ridge is mainly in-plane. 6)Ridge is asymmetric in . 7)Ridge is very wide. 8)Ridge is random. 9)No jet-ridge cross-talk. 10)Ridge may be back-to-back. 11)Ridge seems unrelated to jet. Now let’s go to models… 34Flow and Dissipation Workshop, Trento, Sept. 2009Fuqiang Wang
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In-medium rad. + long. Flow push Ridge increases with centrality. Ridge spectrum a bit harder than bulk. Ridge particle composition similar to bulk. Ridge present in untriggered correlation. Ridge is mainly in-plane. Ridge is asymmetric in . Ridge is very wide. Ridge is random. No jet-ridge cross-talk. Ridge may be back-to-back. Ridge seems unrelated to jet. N. Armesto et al., Phys. Rev. Lett. 93 (2004) 242301 x x x x 35Fuqiang Wang
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Turbulent color field Ridge increases with centrality. Ridge spectrum a bit harder than bulk. Ridge particle composition similar to bulk. Ridge present in untriggered correlation. Ridge is mainly in-plane. Ridge is asymmetric in . Ridge is very wide. Ridge is random. No jet-ridge cross-talk. Ridge may be back-to-back. Ridge seems unrelated to jet. A. Majumder et al., Phys. Rev. Lett. 99 (2004) 042301 x x 36Fuqiang Wang
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Recombination of thermal+shower partons 37 Ridge increases with centrality. Ridge spectrum a bit harder than bulk. Ridge particle composition similar to bulk. Ridge present in untriggered correlation. Ridge is mainly in-plane. Ridge is asymmetric in . Ridge is very wide. Ridge is random. No jet-ridge cross-talk. Ridge may be back-to-back. Ridge seems unrelated to jet. R.C. Hwa, C.B. Chiu, Phys. Rev. C 72 (2005) 034903 x x x Fuqiang Wang
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Momentum kick model 38 Ridge increases with centrality. Ridge spectrum a bit harder than bulk. Ridge particle composition similar to bulk. Ridge present in untriggered correlation. Ridge is mainly in-plane. Ridge is asymmetric in . Ridge is very wide. Ridge is random. No jet-ridge cross-talk. Ridge may be back-to-back. Ridge seems unrelated to jet. C.Y. Wong hep-ph:0712.3282 x x x x Fuqiang Wang
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Transverse flow boost 39 Ridge increases with centrality. Ridge spectrum a bit harder than bulk. Ridge particle composition similar to bulk. Ridge present in untriggered correlation. Ridge is mainly in-plane. Ridge is asymmetric in . Ridge is very wide. Ridge is random. No jet-ridge cross-talk. Ridge may be back-to-back. Ridge seems unrelated to jet. S.A. Voloshin, Phys. Lett. B 632 (2006) 490; E. Shuryak, Phys. Rev. C 76 (2007) 047901 x Fuqiang Wang
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Glasma flux tube fluctuation + radial flow 40 Ridge increases with centrality. Ridge spectrum a bit harder than bulk. Ridge particle composition similar to bulk. Ridge present in untriggered correlation. Ridge is mainly in-plane. Ridge is asymmetric in . Ridge is very wide. Ridge is random. No jet-ridge cross-talk. Ridge may be back-to-back. Ridge seems unrelated to jet. R. Venugopalan et al., arXiv:0902.4435 ridge Fluctuation of color flux tubes excess ridge particles (larger in-plane due to flow?) x Fuqiang Wang
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Summary and open questions Conical emission of correlated particles. Medium response to hard probes. Suggests Mach cone shock waves. – What distortion to Mach angle by medium? – How to extract speed of sound? EOS? Ridge is uniform in pseudo-rapidity. Likely medium itself at early time. – Is it due to color flux tubes? – What additional work to falsify this and other models, or learn something from them? 41Flow and Dissipation Workshop, Trento, Sept. 2009Fuqiang Wang
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Backups
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v2 systematic uncertainties 43Flow and Dissipation Workshop, Trento, Sept. 2009Fuqiang Wang
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On-diag projection Off-diag projection On-diag projection Off-diag projection Jet-like 3-p correlation RP-frame cumulant Lab-frame cumulant 44Flow and Dissipation Workshop, Trento, Sept. 2009Fuqiang Wang
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45Flow and Dissipation Workshop, Trento, Sept. 2009Fuqiang Wang
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trigger particle p T > 3 GeV/c assoc. particle p T =1-2 GeV/c Large combinatorics N jet particles ~ 1, N bkgd particles ~ 20 p T trig =3-4 GeV/c, p T assoc =1-2 GeV/c Extremely difficult analysis. Careful subtraction of bkgd. Extensive assessment of systematics. Combinatorial pair bkgd is huge! 46Flow and Dissipation Workshop, Trento, Sept. 2009Fuqiang Wang
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What’s left on the away-side? first peak second peak φsφs φsφs φsφs Differential pathlength sensitivity 2 3 4 0 /2 0.1 0.2 Peak position Peak area Peak 0.4 0.5 0.6 Peak distance 47Flow and Dissipation Workshop, Trento, Sept. 2009Fuqiang Wang
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Jet constant with s. Ridge decreases with s. Cone increases with s. Jet decreases with p T. Ridge constant with p T. Cone decreases with p T. STAR Preliminary 48Flow and Dissipation Workshop, Trento, Sept. 2009Fuqiang Wang
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Black : Raw signal Pink : Mixed-event background Blue : Scaled bkgd by ZYA1 Red : Raw signal – bkgd 2-particle correlation AuAu ZDC central (0-12%) triggered data, 3<p T Trig <10 GeV/c, 1<p T Asso <3 GeV/c acceptance corrected STAR Preliminary | |<0. 7 Ridge 49Flow and Dissipation Workshop, Trento, Sept. 2009Fuqiang Wang
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3-particle correlation background Raw Raw Raw signal Raw Bkg Hard-Soft Bkg1 Bkg1 Bkg1 Bkg2 correlated Soft-Soft - - 50Flow and Dissipation Workshop, Trento, Sept. 2009Fuqiang Wang
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Jet and Ridge contributions AA like T like : No Jet Only Ridge Ridge (T- A+) A+) = Ridge (T+ A+) A+) Ridge (T+ A- ) A-) = Ridge (T- A- ) A-) Ridge (T+ A-) A+) = Ridge (T+ A+) A+) Ridge (T- A+ ) A-) = Ridge (T- A- ) A-) Netrakanti, QM’09. STAR Preliminary 51Flow and Dissipation Workshop, Trento, Sept. 2009Fuqiang Wang
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