Report

Workshop of European Group on Ultrarelativistic Heavy Ion Physics Close velocity Correlations JINR, Dubna 9-14. 03. 2006 q from STAR to ALICE Jan Pluta, Warsaw University of Technology The starting point 1972 - 4 Kopylov and Podgoretsky settled the basics of correlation femtoscopy: •correlation function, •mixing technique, •role of space-time charakterist... Podgorecki, Kopylov, Smorodinski Dubna, 1974 1975 ... Grishin, propane bubble chamber group and others in Dubna - measured the twoparticle correlations 1981 Lednicky and Lyuboshitz solved the problem of final state interaction Weekly meeting of propane bubble chamber group. The basic notions Two-particle interferometry: p-space separation space-time separation p x q q p p 1 1 2 qside Rside x2 p2 qout 1 1 k p 2 p1 2 qlong Rout • HBT: Quantum interference between identical particles Gaussian model (3-d): – Final-state effects (Coulomb, strong) also can cause correlations, need to be accounted for C (q) P( p1 , p2 ) real event pairs C ( p1 , p2 ) P( p1 )P( p2 ) mixed event pairs 2 2 2 2 2 2 qout Rout qside Rside qlong Rlong C (q , k ) 1 (k ) e ~ 2 1 R 1 q (GeV/c) HBT at RHIC... HBT Excitation Function “RHIC HBT puzzle” •unexpected (small) sizes •Rout/Rside = (approx.)1 •Pt dependence do not agree with models •The same Pt dependence for pp, dAu and AuAu STAR 130 GeV PHENIX 130 GeV Z.Chajęcki, QM’2005 Pion HBT radii from different systems and at different energies scale with (dNch/dη)1/3 RHIC/AGS/SPS Systematics <kT>≈ 400 MeV (RHIC) <kT>≈ 390 MeV (SPS) Lisa, Pratt, Soltz, Wiedemann, nucl-ex/0505014 STAR DATA (pp,dAu,CuCu,[email protected] - prelim.) System expansion: Initial vs Final Size Collisions at 200GeV only Smooth expansion of the system from p+p to Au+Au AuAu: system expands pp (dAu): no or less expansion Proton initial size = 0.89 fm from e-scattering Transverse mass dependence in Au+Au STAR, [email protected], PRC 71 (2005) 044906 0. 0. 0. .2 0.2 0.3 0.4 0.5 0.2 0.3 0.4 0.5 0.6 In Au+Au pT (mT) dependence attributed to collective expansion of the source Calc. with Blast-Wave Retiere, Lisa, PRC 70 (2004) 044907 Consistency check on flow – kaons Hania Gos, Kromeriz’05 More confirmation STAR preliminary Surprising („puzzling”) scaling All pT(mT) dependences of Ratio of (AuAu, CuCu, dAu) HBT radii by pp HBT radii observed by STAR scale with pp although it’s expected that different origins drive these dependences HBT radii scale with pp Scary coincidence or something deeper? pp, dAu, CuCu - STAR preliminary Hania Gos, Kromeriz’05 Adam Kisiel, Fabrice Retiere Nonidentical particle correlations – the asymmetry analysis Heavier particle faster Lighter particle faster Catching up C - interaction time larger •Stronger correlation Moving away C + C Kinematics selection along some direction •Effective + C -1 •Effective Interaction time smaller •Weaker correlation “Double” ratio •Sensitive to the space-time asymmetry in the emission process e.g. kOut, kSide, cos(v,k) k* R.Lednicky, V. L.Lyuboshitz, B.Erazmus, D.Nouais, Phys.Lett. B373 (1996) 30. Pion-Kaon at 200 AGeV kaon faster • Good agreement for same-charge combinations pion faster STAR preliminary • Clear emission asymmetry signal Out double ratio 0.9 syst. Sigma: 17.3 ± 0.8 +- 1.6 syst. fm 6.1 syst. Mean: -7.0 ± 1.2 +- 4.0 syst. fm Side double ratio Pion-Proton 130 AGeV • Good agreement for identical and opposite charge combinations • We observe Lambda peaks at k*~decay momentum of Λ proton faster Λ peaks STAR preliminary Side double ratio 1.0 syst. fm Sigma: 15.1 ± 0.4 +- 1.5 syst. 1.9 syst. Mean: -7.4 ± 0.9 -+3.4 syst. fm Fit assumes source is a gaussian in r*out pion faster Out double ratio Hania Gos, Kromeriz’05 Adam Kisiel, Kromeriz’05 Origins of asymmetry all pion emission times primordial all kaon emission times primordial • Measures asymmetry in pair rest frame is a combination of time and space shifts in source frame • In heavy-ion collisions one expects difference in emission time from resonance decays pion average = 16.1 kaon average = 14.8 time shift = 1.3 THERMINATOR calculation pion emission points side kaon emission points Space asymmetry from flow out proton emission points THERMINATOR calculation • Transverse momentum of particles is composed of the thermal (randomly distributed) and flow (directed “outwards”) components • With no flow average emission point is at center of the source and the length of homogeneity is the whole source • Flow makes the source smaller (“size”-p correlation) AND shifted in outwards direction (x-p correlation) • For particles with large mass thermal motion matters less – they are shifted more in “out” direction. The difference is measured as emission asymmetry. Fourier coefficients of HBT() oscillations • Out-of-plane sources at freeze-out – Pressure and/or expansion time was not sufficient to quench initial shape • From v2 we know... – Strong in-plane flow → significant pressure build-up in system R 2y R 2x R 2y R 2x eccentricity Ry Rx Time Short expansion time plays dominant role in out-of-plane freeze-out source shapes STAR Collaboration, nucl-ex/0312009 Dmitri Peresounko Direct photon interferometry PHENIX; d+Au collisions at √sNN=200 GeV Paul Chung, Stony Brook Technique Devised by: D. Brown, P. Danielewicz, PLB 398:252 (1997). PRC 57:2474 (1998). Emitting source ImagingTechnique Inversion of Linear integral equation to obtain source function 1D Koonin Pratt Eqn. C (q ) 1 4 drr 2 K 0 (q, r )S (r ) Encodes FSI Correlation function Source function (Distribution of pair separations) Inversion of this integral equation == Source Function T.Csorgo, Kromeriz’05 Rewiew of Bose-Einstein/HBT Correlations in high energy heavy ion physics Model F Model G Nature hides her secrets in data (D) Question 0: Do the models (E,F,G,H) describe the data? Answer 0: These models fail, but this is not a puzzle. Q. 1: Are any other models that descibe the data? A. 1: Yes, there are three models (A,B,C) that cannot be excluded (Conf. Lev. > 0.1 %) Q. 2: Do these models have anything in common? A. 2: Yes, and this where the data (D) are. This common part is what Nature is trying to tell us. Model E Model A D Model B Model C Model H Comparison of results of models Acceptable Comparison of results of models Comparison of results of models Comparison of results of models Comparison of results of models Comparison of results of models Comparison of results of models Comparison of results of models Comparison of results of models Comparison of results of models Acceptable Comparison of results of models Comparison of results of models ~Acceptable Comparison of results of models ~Acceptable Comparison of results of models T.Csorgo, Kromeriz’05 The HBT test Less unpromising models: don’t fail fitting Au+Au HBT data @ RHIC – nucl-th/0204054 Multiphase Transport model (AMPT) Z. Lin, C. M. Ko, S. Pal – nucl-th/0205053 `` Hadron rescattering model T. Humanic – nucl-th/0207016 Buda-Lund hydro (hep-ph/9503494, 9509040) T. Csorgo, B. Lörstad, A. Ster et al. (nucl-th/0403074, /0402037, /0311102 ) – hep-ph/0209054 Cracow model (single freeze-out, thermal) W. Broniowski, A. Baran, W. Florkowski – nucl-ex/0307026 Blast wave model (Schnedermann, Heinz) M. A. Lisa, F. Retiere, PRC70, 044907 (2004) – hep-ph/0404140 Time dependent Duke hydro model T. Renk – nucl-th/0411031 Seattle model (quantum opacity) J. G. Cramer, G. A. Miller, J.M.S. Wu, J.-H. Yoon – nucl-th/0507057 Kiev-Nantes model Borysova, Sinyukov, Akkelin, Erazmus, Karpenko Successfull models at RHIC (1): Blastwave T=106 ± 1 MeV <InPlane> = 0.571 ± 0.004 c Spectra <OutOfPlane> = 0.540 ± 0.004 c RInPlane = 11.1 ± 0.2 fm v2 ROutOfPlane = 12.1 ± 0.2 fm Life time () = 8.4 ± 0.2 fm/c Emission duration = 1.9 ± 0.2 fm/c HBT 2/dof = 120 / 86 (Errors are statistical only, CL = 0.91 %) Neglect of resonances F. Retiere, nucl-ex/0405024; F. Retiere and M. A. Lisa, nucl-th/0312024 Successfull model (2): Cracow model Model features: Thermal model included (abundances driven by Tchem and B) Assumes full Hubble flow Sudden freeze-out (at a constant proper-time) Single freeze-out, Tchem = Tkin Boost-invariance nucl-th/0212053 All resonances included, they decay but do not rescatter. Future plans at LHC RHIC/AGS/SPS Systematics <kT>≈ 400 MeV (RHIC) <kT>≈ 390 MeV (SPS) ...and expectations for LHC Assuming the same tendency: 40961/3=16 80001/3=20 Rexpected < 10fm Tom Humanic, Kromeriz’05 Pion freezeout time and z-position for LHC form rescattering calculations Pion freezeout times are about twice as long at LHC compared to RHIC Two-pion correlation function for LHC form rescattering calculations Projected 3D two-pion C2 for LHC Pb+Pb from rescattering for b=8 fm centrality and pT bin 0-200 MeV/c Transverse radius parameters for LHC vs. RHIC Transverse radius parameters are somewhat larger and show a stronger pT dependence for LHC compared with RHIC RLong and parameters for LHC vs. RHIC RLong for LHC is almost twice as large as for RHIC reflecting longer freezeout times; behaves about the same at LHC and RHIC Current status of momentum correlation analysis Results of PPR preparation; Chapter 6.3 Momentum Correlations 1. „HBT-analyser” – a dedicated sofrware for momentum coorelation analysis at ALICE - ready and integrated in Ali-root environment 2. Experimental factors specific for correlation analysis: track splitting, merging, two-particle resolution and PD - evaluated for different two-particle systems 3. Universal fitting procedure for identical and nonidentical particles „Corfit” – ready, but not integrated yet in Ali-root environment 4. Influence of hard processes (jets) on particle correlatins – under investigations 5. Single event pion interferometry will be possible at ALICE Current status of momentum correlation analysis For details see: ALICE-INT-2005-026, One and two-particle resolution and PID ALICE-INT-2005-031, Two-tracks effects at ALICE ALICE-INT-2005-045, Some specific features of momentum correlations to be seen at ALICE (draft-0) • Formalism of two-particle correlations • Particle correlations for expanding sources • Role of Coulomb and strong final state interactions • Nonidentical particle correlations and space-time asymmetries • Azimuthally sensitive HBT • Formation of light (anti)nuclei • Multi-particle Coulomb effects • Correlation measurements of two-particle scattering • Influence of resonance decays on two-particle correlations Some examples Simulation chain for particle correlations Piotr Skowroński Two Particle Resolutions Resolution (r.m.s) [MeV] Qinv Qout Qside Qlong PDC04 TP PDC0 4 + 0.9 1.3 3.4 3.8 0.4 0.4 1 0.8 K K 2.3 4.2 6.4 9.5 0.6 0.5 1.9 2.3 pp 4.0 8.0 9.4 13.0 0.8 0.7 3.2 4.3 K- x x 4.4 4.1 1.2 0.7 1.7 1.1 p x x 5.8 4.2 2.1 0.7 1.8 1.2 K p x x 6.4 8.3 1.9 1.0 2.6 3.2 TP PDC04 TP PDC04 TP Compare the results presented in „Technical Proposal” (TP, in 1995) and obtained from PDC04 (in 2005) Almost the same results after ten years of work – very well ( ! ) : reasonable first estimation, and very good complete reconstruction. Track Merging • Anti-Merging cut as implemented by STAR – Cutting on average distance between two tracks in TPC – Space coordinates of tracks are calculated assuming helix shape using track parameters as reconstructed in the inner part of TPC Single event pion-pion interferometry (with FSI)... by Zbyszek Chajęcki, (ro=8fm) Single event pion-pion interferometry by Hania GOS We are looking forward, working, and waiting for the first event of ALICE Two-particle kinematics LCMS: (P1+P2)z=0 Getting quantitative What can be probed through fitting? Source of particle 2 Source of particle 1 r Separation between source 1 and 2 in pair rest frame Boost to pair rest frame r [fm] r* =pairr –pairt r* separation in pair rest frame Function of pair(pair) r* [fm] When fitting “double-ratios” two independent variables are accessible: - Mean shift (<r*>) or μ - Sigma (r*) Two important events; sources of information and discussion forum: Quark Matter Conference and satellite topical meeting.