Transcript ridge
Cone is medium response, Ridge is medium itself. Fuqiang Wang Purdue University For the STAR Collaboration Plan of talk • Away-side cone: medium response to hard probes • Near-side ridge: medium response or itself? Bridger ridge, Montana Fuqiang Wang Flow and Dissipation Workshop, Trento, Sept. 2009 2 The away-side structure Au+Au High pT trigger particle Df PHENIX p+p associated particles trigger jet Awayside -1 0 Fuqiang Wang 1 p Df Flow and Dissipation Workshop, Trento, Sept. 2009 3 Possible physics scenarios pTtrig=3-4 GeV/c, pTassoc=1-2.5 GeV/c trigger jet trigger jet Away-side -1 0 Df p 1 away trigger jet Surface bias event 1 away Fuqiang Wang event 2 deflected jets Mach cone away Flow and Dissipation Workshop, Trento, Sept. 2009 4 3-particle azimuthal correlation trigger jet trigger jet event 1 event 2 away away deflected jets away Mach cone Df2 = f2-ftrig p Df2 0 0 signature of conical emission p 0 Fuqiang Wang away p Df1= f1-ftrig 0 Flow and Dissipation Workshop, Trento, Sept. 2009 p Df1 5 Evidence of conical emission STAR, PRL 102, 052302 (2009) d+Au Au+Au central trigger Df2 p 0 0 Fuqiang Wang p Df1 Flow and Dissipation Workshop, Trento, Sept. 2009 Away-side 6 Conical emission angle STAR, PRL 102, 052302 (2009) trigger q = 1.37 ± 0.02 (stat.) ± 0.06 (syst.) q Away-side Fuqiang Wang Constant cone angle vs pT suggests Mach Cone shock waves may be the underlying mechanism. Flow and Dissipation Workshop, Trento, Sept. 2009 7 Higher trigger pT 1 < pTassoc < 2 GeV/c 4 < pTtrig < 6 GeV/c 1 < pTassoc < 2.5 GeV/c 6 < pTtrig < 10 GeV/c 1 < pTassoc < 2.5 GeV/c Fuqiang Wang Flow and Dissipation Workshop, Trento, Sept. 2009 8 Theory calculations pQCD + hydro: Neufeld et al. arXiv:0807.2996 quark v = 0.99955 r x ( x) 2 mD T r x gz ( x) mD2 T Parton energy loss: Renk et al. PRC 76, 014908 (2007) Fuqiang Wang Flow and Dissipation Workshop, Trento, Sept. 2009 9 AdS/CFT Correspondence Maldacena (1997), Gubser, Klebanov,Polyakov; Witten (1998) N = 4 Super-Yang-Mills theory in 4d with SU(NC) A string theory in 5d AdS YM observables at infinite NC and infinite coupling can be computed using classical gravity. Chesler & Yaffe arXiv:0712.0050 Heavy quark u = 0.75c Measure heavy quark Mach-cone shock waves: Experimental consequence of string theory? Fuqiang Wang Flow and Dissipation Workshop, Trento, Sept. 2009 10 Speed of sound? p EOS: p() cS 2 p / HG cS = 0.45 QGP cS = √1/3 = 0.58 Mixed phase cS = 0 qM = 1.37 speed of sound cS ~ 0.2 cS far smaller than HG or QGP. Must have mixed phase (phase transition). However, model calculations indicate that Mach Cone angle can be altered by medium flow. Fuqiang Wang Flow and Dissipation Workshop, Trento, Sept. 2009 11 Investigating flow effect on cone angle Fit to large Dh azimuthal correlations Au+Au 20-60%, 3<pTtrig<4, 1<pTtrig<2 GeV/c STAR Preliminary 2 Gaus: Ridge at 0 and ridge at p, same shape, diff. magnitudes 2 Gaus: identical conical emission peaks symmetric about p. Fuqiang Wang Flow and Dissipation Workshop, Trento, Sept. 2009 13 STAR Preliminary STAR Preliminary Fuqiang Wang • Cone angle takes off after trigger fs=45o. • Split in pT after fs=45o. • Cone angle ~constant over pT at fs<45o. Flow and Dissipation Workshop, Trento, Sept. 2009 14 Is there a back-to-back RIDGE? Away-Side Ridge Away 1 RP Ridge Near Jet Trig. Away 2 Fuqiang Wang Flow and Dissipation Workshop, Trento, Sept. 2009 15 Connection between near- and away-side STAR Preliminary Away-side -1 0 Fuqiang Wang 1 p Df Flow and Dissipation Workshop, Trento, Sept. 2009 16 • • • • Separate 1st and 2nd quadrants trigger particles Azimuthal correlation for large |Dh|>0.7 Near-side ridge Gauss repeated at “+π” Subtract back-to-back symmetric ridge peaks STAR Preliminary ∆φ ∆φ ∆φ ∆φ ∆φ ∆φ ∆φ ∆φ ∆φ ∆φ ∆φ ∆φ Fuqiang Wang Flow and Dissipation Workshop, Trento, Sept. 2009 17 Away-side asymmetric cone positions STAR Preliminary 1st cone 2nd Cone peak ∆φ RP 2nd Cone trigger 1st cone peak φs • • Evidence of flow effect on conical emission. Important to disentangle flow effect and conical emission angle. Fuqiang Wang Flow and Dissipation Workshop, Trento, Sept. 2009 18 The longitudinal ridge associated h~0 particle d+Au h~1 trigger particle pT > 3 GeV/c Dh Df |Df|<0.7 High-pT trigger particle Au+Au assoc. particle pT =1-2 GeV/c Fuqiang Wang ridge Bridger ridge, Montana Flow and Dissipation Workshop, Trento, Sept. 2009 19 What’s already known about ridge • Ridge increases with centrality. • Ridge pt spectrum is a bit harder than bulk. • Ridge particle composition similar to bulk. STAR, arXiv:0909.0191 • Ridge present in untriggered correlation. M. Daugherity (STAR), QM’08, J.Phys.G35:104090,2008 Ridge extended to very large Dh STAR, arXiv:nucl-ex/0701061 PHOBOS, arXiv:0903.2811 2.7<|Df|<3.9 > 1.0 GeV/c pTassoc STAR Preliminary Fuqiang Wang Flow and Dissipation Workshop, Trento, Sept. 2009 21 New insights from RP-dependent dihadron correlations Dh cut to “separate” jet and ridge |∆η|>0.7 = ridge + away-side Jet = (|∆η|<0.7) – Accept.*(|∆η|>0.7) assuming ridge is uniform in ∆η. Au+Au 20-60%, 3<pTtrig<4, 1.5<pTtrig<2.0 GeV/c d+Au Fuqiang Wang Feng, QM’06. STAR Preliminary Flow and Dissipation Workshop, Trento, Sept. 2009 23 Ridge decreases with RP STAR Preliminary Ridge drops when trigger particle moves away from RP. in-plane Fuqiang Wang trigger |fs| Flow and Dissipation Workshop, Trento, Sept. 2009 out-of-plane 24 A model prediction motivated by data Correlated Emission Model (CEM) 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. Fuqiang Wang Flow and Dissipation Workshop, Trento, Sept. 2009 25 Remove away-side from large Dh correlation Konzer, QM’09. STAR Preliminary Trig. pt=3-4 GeV/c, assoc pt=1-1.5 GeV/c Au-Au 20-60% |∆η|>0.7 ZYAM φs = 0 to -15 Ridge -15 to -30 -30 to -45 -45 to -60 -60 to -75 -75 to -90 0.05 Jet 0 -1 0 1 π ∆f = fassoc – ftrig • Jet remains constant • Ridge Decreases Fuqiang Wang • Jet symmetric • Ridge asymmetric Flow and Dissipation Workshop, Trento, Sept. 2009 26 Correlation Asymmetry STAR Preliminary trigger pt=3-4 GeV/c v2 syst. Ridge CEM model A N 0f 1 - N -1f 0 N 0f 1 N -1f 0 • Away-side is Asymmetric (not shown in plot). • Jet is symmetric. Ridge: assoc pt=1-1.5 GeV/c Ridge: assoc pt=1.5-2 GeV/c Jet: assoc pt=1.5-2 GeV/c in-plane Fuqiang Wang Jet |fs|= ftrig – ψRP out-ofplane • Ridge is Asymmetric! • Ridge may be due to jet-flow alignment. Flow and Dissipation Workshop, Trento, Sept. 2009 27 New insights from 3-particle Dh-Dh correlation How does long Dh come about? Many models on the market. 3-particle Dh-Dh correlations |Df|<0.7 3<pTtrig<10 GeV/c, 1<pTassoc<3 GeV/c Netrakanti, QM’09. arXiv:0907.4744 STAR Preliminary N. Armesto et al., Phys. Rev. Lett. 93 (2004) 242301 Fuqiang Wang d+Au Nucleus-Nucleus 2009, August 2009 Central Au+Au 29 3-particle Dh-Dh correlations trig<10 3<pT GeV/c 1<pTassoc<3 GeV/c |Df|<0.7 Netrakanti, QM’09. STAR Preliminary dAu AuAu 12% Charge independent (All) STAR Preliminary AALike = (AALikeTLike + AALikeTUnlike) AAUnlike = All - AALike Separate jet and ridge Jet has charge ordering ridge does not jet ridge Netrakanti, QM’09. arXiv:0907.4744. STAR Preliminary Same-sign triplets: Only ridge, no jet. R Ridge is structureless x Netrakanti, QM’09. arXiv:0907.4744. STAR Preliminary Radial Projection Angular Projection STAR Preliminary (jet) = 0.25 0.09 (ridge) = 1.53 0.41 Fuqiang Wang No prominent subtructures in ridge. Flow and Dissipation Workshop, Trento, Sept. 2009 32 Ridge-jet cross pairs Netrakanti, QM’09. arXiv:0907.4744. STAR Preliminary From 3-particle Dh -Dh correlation: From 2-particle Dh correlation: N pairs 1.42-0.19 0.31 N ridge pairs 1.26-0.13 0.27 N assoc 1.1 N ridge 0.8 N jet pairs and jet-ridge pairs 0.16-0.06 0.04 N jet-like 0.3 Let x fraction of events containing ridge y fraction of events containing jet z fraction of events containing both ridge and jet Assuming Poisson statistics: x (0.8 / x) 2 1.26 x 0.50 y (0.3 / y ) 2 2 (0.8 / x) (0.3 / y ) z 0.16 z 0.17 y - 0.09 y 0.53, z 0.08 Fuqiang Wang With systematic errors: x 0.50-0.05 0.11 y 0.53-0.15 0.20 z 0.08-0.05 0.04 Ridge and jet appear to be anti-correlated. 33 Experimental facts 1) 2) 3) 4) 5) 6) 7) 8) 9) 10) 11) 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 Df. Ridge is very wide. Ridge is random. No jet-ridge cross-talk. Ridge may be back-to-back. Ridge seems unrelated to jet. Now let’s go to models… Fuqiang Wang Flow and Dissipation Workshop, Trento, Sept. 2009 34 In-medium rad. + long. Flow push N. Armesto et al., Phys. Rev. Lett. 93 (2004) 242301 • Ridge increases with centrality. • Ridge spectrum a bit harder than bulk. • Ridge is mainly in-plane. • Ridge is asymmetric in Df. • Ridge is very wide. • No jet-ridge cross-talk. • Ridge may be back-to-back. x• Ridge particle composition similar to bulk. x• Ridge present in untriggered correlation. x• Ridge is random. Fuqiang Wang x• Ridge seems unrelated to jet. 35 Turbulent color field A. Majumder et al., Phys. Rev. Lett. 99 (2004) 042301 • 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 Df. • Ridge is random. • No jet-ridge cross-talk. • Ridge may be back-to-back. x• Ridge is very wide. Fuqiang Wang x• Ridge seems unrelated to jet. 36 Recombination of thermal+shower partons R.C. Hwa, C.B. Chiu, Phys. Rev. C 72 (2005) 034903 • Ridge increases with centrality. • Ridge spectrum a bit harder than bulk. • Ridge particle composition similar to bulk. x• Ridge present in untriggered correlation. • Ridge is mainly in-plane. • Ridge is asymmetric in Df. • Ridge is random. • No jet-ridge cross-talk. • Ridge may be back-to-back. x• Ridge is very wide. Fuqiang Wang x• Ridge seems unrelated to jet. 37 Momentum kick model C.Y. Wong hep-ph:0712.3282 • Ridge increases with centrality. • Ridge spectrum a bit harder than bulk. • Ridge particle composition similar to bulk. x• Ridge present in untriggered correlation. x• Ridge is mainly in-plane. x• Ridge is asymmetric in Df. Fuqiang Wang • Ridge is very wide. • Ridge is random. • No jet-ridge cross-talk. • Ridge may be back-to-back. x• Ridge seems unrelated to jet. 38 Transverse flow boost S.A. Voloshin, Phys. Lett. B 632 (2006) 490; E. Shuryak, Phys. Rev. C 76 (2007) 047901 • 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 Df. • Ridge is very wide. • Ridge is random. • Ridge may be back-to-back. • Ridge seems unrelated to jet. x• No jet-ridge cross-talk. Fuqiang Wang 39 Glasma flux tube fluctuation + radial flow ridge ridge R. Venugopalan et al., arXiv:0902.4435 Fluctuation of color flux tubes excess ridge particles (larger in-plane due to flow?) Fuqiang Wang • 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 Df. • Ridge is very wide. • Ridge is random. • Ridge may be back-to-back. • Ridge seems unrelated to jet. x• No jet-ridge cross-talk. 40 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? Fuqiang Wang Flow and Dissipation Workshop, Trento, Sept. 2009 41 Backups v2 systematic uncertainties Fuqiang Wang Flow and Dissipation Workshop, Trento, Sept. 2009 43 ˆ3 (t ,1,2 ) 3 (t ,1,2 ) - 2 (1,2 ) 1 (t ) - 2 (t ,1 ) 1 (2 ) - 2 (t ,2 ) 1 (1 ) 21 (t ) 1 (1 )1 (2 ) Jet-like 3-p correlation Fuqiang Wang RP-frame cumulant Lab-frame cumulant On-diag projection On-diag projection Off-diag projection Off-diag projection Flow and Dissipation Workshop, Trento, Sept. 2009 44 Fuqiang Wang Flow and Dissipation Workshop, Trento, Sept. 2009 45 Large combinatorics pTtrig=3-4 GeV/c, pTassoc=1-2 GeV/c trigger particle pT > 3 GeV/c Df N jet particles ~ 1, N bkgd particles ~ 20 Combinatorial pair bkgd is huge! assoc. particle pT =1-2 GeV/c Extremely difficult analysis. Careful subtraction of bkgd. Extensive assessment of systematics. Fuqiang Wang Flow and Dissipation Workshop, Trento, Sept. 2009 46 What’s left on the away-side? 0.2 4 second peak 0.6 3 Peak position 0.5 2 first peak φs Peak area 0.1 0 φs 0.4 p/2 Peak φs Differential pathlength sensitivity Peak distance Fuqiang Wang Flow and Dissipation Workshop, Trento, Sept. 2009 47 STAR Preliminary • Jet constant with fs. • Ridge decreases with fs. • Cone increases with fs. STAR Preliminary • Jet decreases with pT. • Ridge constant with pT. • Cone decreases with pT. Fuqiang Wang Flow and Dissipation Workshop, Trento, Sept. 2009 48 2-particle correlation AuAu ZDC central (0-12%) triggered data, 3<pTTrig<10 GeV/c, 1<pTAsso<3 GeV/c Black : Raw signal Pink : Mixed-event background Blue : Scaled bkgd by ZYA1 STAR Preliminary |Df|<0. 7 |Df|<0. 7 Red : Raw signal – bkgd Dh acceptance corrected Ridge Fuqiang Wang Flow and Dissipation Workshop, Trento, Sept. 2009 49 3-particle correlation background - correlated - Raw Raw Raw signal Raw Bkg Hard-Soft Bkg1 Bkg1 Soft-Soft Bkg1 Bkg2 Fuqiang Wang Flow and Dissipation Workshop, Trento, Sept. 2009 50 Jet and Ridge contributions Netrakanti, QM’09. STAR Preliminary AAlikeTlike : No Jet Only Ridge Ridge (T- A+) A+) Ridge (T+ A- ) A-) Ridge (T+ A-) A+) Ridge (T- A+ ) A-) Fuqiang Wang = Ridge (T+ A+) = Ridge (T- A- ) = Ridge (T+ A+) = Ridge (T- A- ) Flow and Dissipation Workshop, Trento, Sept. 2009 A+) A-) A+) A-) 51