Transcript Document
Review of pt Fluctuations and Correlations Duncan Prindle Firenze, IT July 7, 2006 A bit of history… • • • • In the 90s we planned for a QCD phase transition RHIC data did contain large-amplitude fluctuations But critical fluctuations were not seen at full energy Instead, correlations reveal copious low-Q2 partons if you can’t get rid of the noise … study the noise! –Penzias and Wilson QCD from the bottom up Prindle 2 Agenda • • • • Prindle pt fluctuations, scaling and inversion pt angular autocorrelations Recoil response of the bulk medium Energy dependence of pt correlations 3 COBE WMAP pt Fluctuations minijets in nuclear collisions hadron pt is drawn from local parent blackbody radiation local parent velocity correlations h f collision axis dv dT pt pt fluctuating local mean hard component localized on (h,f) differently in each p-p or Au-Au event 1) local temperature variation dT 2) local velocity variation dv Prindle one bang one Au-Au event 4 pt Fluctuation Measures s rab º 2 a s s a=b 2 ab 2 pt :n 2 b ® rpt ,ab ( pt - n pˆ t )a ( pt - n pˆ t )b Pearson’s normalized = covariance: bins a, b s p2ˆ t na nb 2 2 ˆ d x p d x n d x p / n d x t t pˆ pˆ rp ,aa STAR 2 t t t scale-dependent variance difference d ptid ptj i j ( pt n pˆ t )2 / n(n 1) p2ˆ t 1/(n 1) pt pt n pˆ t CERES pt Prindle 2 pt :n / n pˆ 2 t Fpt 2 / n pˆ t STAR NA49 PHENIX pt ,data pt ,mix 1 1 p2t ,dyn / p2ˆ t 1/ n 1 5 pt Fluctuations – NA49 yp [4,5.5], pt<1.5 GeV/c Φpt 17 GeV Phys. Rev. C 70, 034902 (2004) Phys. Lett. B459, 679 (1999) first pt fluctuation measurements, first search for critical fluctuations Prindle 6 pt Fluctuations – PHENIX Fpt 130 GeV 200 GeV Phys. Rev. Lett. 93, 092301 (2004) Phys. Rev. C 66, 024901 (2002) Prindle first RHIC fluctuation measurements first centrality dependence first indications of mechanism: hard scattering 7 pt Fluctuations – CERES Φpt 8 GeV 12 GeV Σpt 17 GeV Nucl. Phys. A 727, 97 (2003) first non-zero pt measurements first h scale dependence first energy dependence estimate further hints of physical mechanism and structure of angular correlations Σpt Prindle 8 pt Fluctuations – STAR 200 GeV data 130 GeV reference (data – ref) / data Phys. Rev. C 71, 064906 (2005) 20 huge effect! scale-dependent variance difference Phys. Rev. C 72, 044902 (2005) J. Phys. G 32, L37 (2006) units of Poisson rms what mechanisms contribute? Prindle 9 Inverting pt Fluctuation Scaling how is pt distributed event-wise on (h,f)? J. Phys. G 32, L37 (2006) full STAR acceptance pt autocorrelation r/√rref f 20-30% subtract multipoles fluctuation inversion r/√rref pt fluctuations r/√rref variance excess 70-80% centrality 0-5% pt fluctuation scale dependence inverted to pt autocorrelations Prindle r/√rref J. Phys. G 31, 809 (2005) T. A. Trainor, R. J. Porter and D. J Prindle, J. Phys. G 31, 809 (2005) 10 h Compare with p-p pt Autocorrelations p-p 200 GeV minbias p-p 200 GeV nch > 9 STAR preliminary CI=LS+US r/√rref r/√rref direct – from pair counting Hijing Au-Au 200 GeV 70-80% data Au-Au 200 GeV r/√rref Phys. Lett. B 632, 197 (2006) J. Phys. G 32, L37 (2006) Prindle from fluctuation inversion r/√rref r/√rref CD=LS–US isovector pt correlations 11 PID Autocorrelations – 62 GeV Au-Au STAR preliminary r/√rref LS - pt pion HBT US pions pt Prindle r/√rref LS - n STAR preliminary US pt US US kaons n US LS protons n 12 Hijing Identified Particles pt [0.15,1.0] GeV/c pp LS, pt [0.15,1.0] GeV/c r/√rref K-K US, pt pp n is all ‘strings’ pp US, pt Prindle r/√rref K-K LS is flat K-K US, n p-K LS, pt p-K n is all ‘strings’ p-K US, pt 13 PID Crosscorrelations – 62 GeV Au-Au STAR preliminary LS LS n p-p n p-K US LS Prindle pt US US STAR preliminary LS pt US 14 K Possible Interpretation a recoil? a pt b jt b a b a string picture – Hijing/Pythia contact plane f2 df Prindle jty ,2 K+ STAR preliminary K-K US pt localized on thrust due to flavor conservation low-pt cut: large angles f jt / pt data pt autocorrelation Hijing pt autocorrelation h dpt low-Q2 fragmentation picture pt,part kinematic limit z jty ,1 pt,2 ˆt yt minijet a f1 yz b pt,1 back-to-back: jt conservation Hijing number autocorrelation K-K US pt K-K US n 15 peak amplitudes B1 peak widths h B2 data 80-90% fit residuals f fit fit peak data fit peak Model Fits red shifts and blue shifts 20-30% B1 data fit peak B3 B2 ~ p-p Prindle negative structure is unanticipated –what is the origin? 16 B1 Data and Monte Carlo B2 hijing pQCD hijing B1 mean participant path length pQCD data Hijing does not predict strong h broadening or negative structure Hijing centrality dependence deviates strongly from data Hijing 70-80% quench on quench off 0-10% Prindle J. Phys. G 32, L37 (2006) Phys. Lett. B 632, 197 (2006) 0-10% 17 Recoil Response of the QCD Medium Au-Au – 200 GeV red shifts and blue shifts p-p 200 GeV pt autocorrelations fragments STAR preliminary r/√rref low-Q2 ‘jet’ h recoil Au-Au 200 GeV data fit peak colored medium p-p A-A centrality Hijing B1 quench-on medium response Prindle Hubble flow 18 pt Fluctuations – SPS RHIC – I fluctuation scale and energy dependence correlation centrality and energy dependence full STAR acceptance dramatic increase of per-particle fluctuations with collision energy Prindle centrality 19 pt Fluctuations – SPS RHIC – II scale dependence df 2p STAR ! Hijing ‘string’ structure in Hijing does not appear in Au-Au data direct comparison with CERES pt ? CERES NPA727:97, 2003 STAR df 2p pt pt :n SSC CERES upper limits Prindle dramatic increase of pt fluctuations with increasing sNN ln sNN /10 GeV 20 Summary • Inversion of pt fluctuations provides first access to pt autocorrelations – direct pair-counting is also possible • pt correlations: temperature/velocity structure of A-A • pt correlation structure reveals complex parton dissipation process in A-A collisions relative to p-p • Identified-particle correlations reveal new physics • Bulk-medium recoil response to parton stopping • Strong energy dependence of pt fluctuations Prindle 21 2 pt :n 2 Dynamical – 2 pt :n δp tiδp tj . Hijing 200 GeV Au-Au 65-85% central ( pt n pˆ t )2 p2ˆ t (n 1) d ptid ptj n scale dependence i j (n-1) p2t ,dynamical ( pt n pˆ t )2 n n 1 2 n 1 pˆ t n n n 1 n 1 n = 30 δp tiδp tj fluctuations r/rref (GeV/c)2 autocorrelations physical correlations Prindle **r/rref** (GeV/c)2 fluctuation inversion unphysical biased measure doesn’t tolerate low multiplicities unphysical 22 Parton Dissipation and Intermediate pt Au-Au centrality dependence mid-central Au-Au transport hydro r/√rref r/√rref r/√rref transport RAA 6 GeV transport r/rref 0.15 GeV r/√rref r/rref p-p peripheral Au-Au central Au-Au 2 GeV pt angular correlations Prindle 0.15 GeV number correlations on pt/yt complementary evolution of fragment correlations on angle and on transverse momentum/rapidity 23 pt Fluctuations – Survey NA49 yp [4,5.5], pt<1.5 GeV/c 17 GeV PHENIX CERES 200 GeV Phys.Rev.Lett.93:092301,2004 8 GeV 12 GeV 17 GeV Phys.Lett.B459, 679 (1999) 130 GeV Phys.Rev.C70, 034902 (2004) Nucl.Phys.A727, 97 (2003) Prindle Phys.Rev.C66, 024901 (2002) 24 pt Fluctuations – SPS RHIC – II scale dependence full STAR acceptance df 2p STAR STAR pt ? centrality STAR df 2p pt pt :n CERES Prindle CERES NPA727:97, 2003 ! Hijing dramatic increase of pt fluctuations with increasing sNN ln ‘string’ structure in Hijing does not appear in Au-Au data sNN /10 GeV 25 PID Autocorrelations – 62 GeV Au-Au pt kaons n Prindle LS US US US pt pions LS US protons: pt has no structure e-e n LS protons pions: LS is only HBT n US 26 PID Crosscorrelations – 62 GeV Au-Au LS LS pt US pt US p-K LS p-p LS n Prindle n US no significant K-p structure US 27 Summary • Inversion of pt fluctuations provides first access to pt autocorrelations – direct pair-counting is also possible • pt correlations: temperature/velocity structure of A-A • pt correlation structure reveals complex parton dissipation process in A-A collisions relative to p-p • Strong disagreement with pQCD Hijing Monte Carlo • Bulk-medium recoil response to parton stopping • Strong energy dependence of pt fluctuations Prindle 29