Femtoscopy in heavy ion collisions Part 2 Mike

Femtoscopy in heavy ion collisions - Part 2 Mike Lisa The Ohio State University ! “School” lecture May 2005 ! The Berkeley School Femtoscopy - malisa 1

2 Outline Lecture I - basics and sanity check • Motivation (brief) • Formalism (brief reminder) – accessible geometric substructure • Some experimental details • 2 decades* of data systematics – system size: AB, |b|, Npart. . . – system shape: (P, b) Lecture II - dynamics (insanity check? ) • data systematics [cnt’d] – boost-invariance? : Y – transverse dynamics: k. T, m. T – new substructure: m 1≠m 2 • Interpretations (& puzzles) – Messages from data itself – Model comparisons – Prelim. comparison: pp, d. A • Summary * in time and in s. NN May 2005 The Berkeley School - Femtoscopy - malisa

Motivation Formalism Experiment Strongly-interacting 6 Li released from an asymmetric trap O’Hara, et al, Science 298 2179 (2002) Trends 3 Models What can we learn? ? in-planeextended transverse FO shape + collective velocity evolution time estimate check independent of RL(p. T) out-of-plane-extended May 2005 Teaney, & School Shuryak- Femtoscopy nucl-th/0110037 The. Lauret, Berkeley - malisa

Motivation Formalism Experiment Trends Models Blast wave : the truth, or something like it F. Retière , QM 04 RY Spectra RX v 2 F. Retière & MAL PRC 70 044907 (2004) • generalized anisotropic BW in ubiquitous use • consistent picture capturing essence of data • homo. region “whole source” with realistic flow gradients May 2005 The Berkeley School - Femtoscopy - malisa HBT 4

Motivation Formalism Experiment Extracting FO shape/size Trends out Models side • 2 nd - order oscillations in radii (n>2 negligible) • characterize each k. T bin with 7 numbers: R 2 os, 0 = 0 by symmetry [Heinz, Hummel, MAL, Wiedemann PRC 66, 044903] out-side in no-flow scenario. . . U. Wiedemann PR C 57 266 (1998) MAL, U. Heinz, U. Wiedemann PL B 489 287 (2000) May 2005 F. Retière & MAL PRC 70 School 044907 -(2004) The Berkeley Femtoscopy - malisa long 5

Motivation Formalism Experiment Trends Models Extracting FO shape/size • 2 nd - order oscillations in radii (n>2 negligible) • characterize each k. T bin with 7 numbers: R 2 os, 0 = 0 by symmetry [Heinz, Hummel, MAL, Wiedemann PRC 66, 044903] in no-flow scenario. . . U. Wiedemann PR C 57 266 (1998) MAL, U. Heinz, U. Wiedemann PL B 489 287 (2000) continues to be good approximation even with flow! (~30%) May 2005 F. Retière & MAL PRC 70 School 044907 -(2004) The Berkeley Femtoscopy - malisa /2 6

Motivation Formalism Experiment Trends Extracting FO shape/size • 2 nd - order oscillations in radii (n>2 negligible) • characterize each k. T bin with 7 numbers: R 2 os, 0 = 0 by symmetry [Heinz, Hummel, MAL, Wiedemann PRC 66, 044903] in no-flow scenario. . . U. Wiedemann PR C 57 266 (1998) MAL, U. Heinz, U. Wiedemann PL B 489 287 (2000) continues to be good approximation even with flow! (~30%) May 2005 F. Retière & MAL PRC 70 School 044907 -(2004) The Berkeley Femtoscopy - malisa Models 7

Motivation Formalism Experiment Trends Models Measured final source shape STAR, PRL 93 012301 (2004) central collisions mid-central collisions peripheral collisions Expected evolution: May 2005 The Berkeley School - Femtoscopy - malisa 8

Motivation Formalism Experiment Trends Models Evolution of size and shape @RHIC STAR PRC 71 044906 (2005) STAR PRL 93 012301 (2004) l ina f nit ial = 2 i Rfinal/Rinitial 2. 5 1 0 100 200 300 ~ x 2 size increase Npart 400 ~ 1/2 shape reduction Initial size/shape estimated by Glauber calculation May 2005 The Berkeley School - Femtoscopy - malisa 9

10 Evolution ahead Detour May 2005 The Berkeley School - Femtoscopy - malisa

Motivation Formalism Experiment Trends Models as. HBT systematics (1/100 * s. NN) • = 0 -2 (not 0 - ) first-order plane used Au+Au s. NN = 2. 3 Ge. V; b 5 fm • similar oscillations in purely transverse radii • out-long & side-long? • new symmetry! E 895, PLB 496 1 (2000) May 2005 The Berkeley School - Femtoscopy - malisa 11

Motivation Formalism Experiment out-side-long versus x-y-z • Source in b-fixed system: (x, y, z) • Space/time entangled in pair system (x. O, x. S, x. L) Trends side 12 Models y K out b x (several terms vanish @ p. T = y = 0) May 2005 U. Wiedemann, PRC 57, 266 (1998) MAL, U. Heinz, U. Wiedemann PLB 489, 287 (2000) The Berkeley School - Femtoscopy - malisa

13 First-order information in HBT(f) y 2 nd-harmonic oscillations from elliptical transverse shape b x 1 st-harmonic oscillations: spatial tilt angle q. S y x qs z (Beam) May 2005 Coordinate space! The Berkeley School - Femtoscopy - malisa

14 Data: - correlation functions Au(4 AGe. V)Au, b 4 -8 fm 2 D projections ( ) C(q) 1 D projections, =45° out side long lines: projections of 3 D Gaussian fit • 6 components to radius tensor: i, j = o, s, l E 895, PLB 496 1 (2000) May 2005 The Berkeley School - Femtoscopy - malisa

Cross-term radii Rol, Ros, Rsl quantify “tilts” in correlation functions fit results to correlation functions Lines: Simultaneous fit to HBT radii to extract underlying geometry May 2005 The Berkeley School - Femtoscopy - malisa 15 ( )

16 Images of --emitting sources (scaled ~ x 1014) y similar to naïve overlap: b~5 fm y x’ x’ 2 AGe. V 3 fm z y q. S=47° x’ 4 AGe. V z 6 AGe. V q. S=37° z q. S=33° Large, positive tilt angles x May 2005 The Berkeley School - Femtoscopy - malisa x x

17 Opposing average tilts in p, x & the physics of flow + 6 AGe. V B. Caskey, E 895 May 2005 z (fm) • “antiflow” (negative tilt in p-space) • x-space tilt in positive direction non-hydro nature of flow (@ AGS) RQMD The Berkeley School - Femtoscopy - malisa Au(2 Ge. V)Au x (fm)

18 • transverse shape: • non-trivial excitation function • increased flow*time rounder FO geometry @ RHIC • insufficient [flow]x[time] to become in-plane AGS: FO init RHIC: FO < init (approximately same centrality) s. NN (Ge. V) May 2005 The Berkeley School - Femtoscopy - malisa

(o ) 19 AGS • transverse shape: • non-trivial excitation function • increased flow*time rounder FO geometry @ RHIC • insufficient [flow]x[time] to become in-plane • Spatial orientation: • another handle on flow & time • HUGE tilts @ AGS!! • RHIC? • QGP-induced orientation? May 2005 STAR: soon ? ? s. NN (Ge. V) y The Berkeley School - Femtoscopy - malisa x qs z (Beam)

20 v 1 predictions (QGP invoked) x-p transverse-longitudinal coupling may be affected in early (v 1) stage J. Brachmann et al. , Phys. Rev. C. 61 024909 (2000) May 2005 L. P. Csernai, D. Rohrich: Phys. Lett. B 458 (1999) 454 The Berkeley School - Femtoscopy - malisa

(o ) 21 AGS • transverse shape: • non-trivial excitation function • increased flow*time rounder FO geometry @ RHIC • insufficient [flow]x[time] to become in-plane • Spatial orientation: • another handle on flow & time • HUGE tilts @ AGS!! • RHIC? • QGP-induced orientation? • requires true 3 D dynamical model (explicitly non-B. I. ) May 2005 STAR: soon ? ? ? s. NN (Ge. V) y The Berkeley School - Femtoscopy - malisa x qs z (Beam)

22 x 2 size increase & decreasing deformation -- ? collective expansion? -- Spectra Evolution ahead v 2 Resume legal speed May 2005 HBT The Berkeley School - Femtoscopy - malisa

23 Decreasing R(p. T) • usually attributed to collective flow • flow integral to our understanding of R. H. I. C. ; taken for granted • femtoscopy the only way to confirm x-p correlations – impt check May 2005 & -Heinz, QGP 3 nucl-th/0305084 The Berkeley. Kolb School Femtoscopy - malisa

24 Decreasing R(p. T) • usually attributed to collective flow • flow integral to our understanding of R. H. I. C. ; taken for granted • femtoscopy the only way to confirm x-p correlations – impt check Non-flow possibilities • cooling, thermally (not collectively) expanding source • combo of x-t and t-p correlations early times: small, hot source late times: large, cool source May 2005 The Berkeley School - Femtoscopy - malisa

25 Decreasing R(p. T) • usually attributed to collective flow • flow integral to our understanding of R. H. I. C. ; taken for granted • femtoscopy the only way to confirm x-p correlations – impt check Non-flow possibilities • cooling, thermally (not collectively) expanding source • combo of x-t and t-p correlations May 2005 MAL et al, School PRC 49 2788 (1994) The Berkeley - Femtoscopy - malisa

26 Decreasing R(p. T) • usually attributed to collective flow • flow integral to our understanding of R. H. I. C. ; taken for granted • femtoscopy the only way to confirm x-p correlations – impt check Non-flow possibilities • cooling, thermally (not collectively) expanding source • combo of x-t and t-p correlations • hot core surrounded by cool shell • important ingredient of Buda-Lund hydro picture e. g. Csörgő & Lörstad PRC 54 1390 (1996) May 2005 The Berkeley School - Femtoscopy - malisa

27 Each scenario generates x-p correlations but… Decreasing R(p. T) • usually attributed to collective flow • flow integral to our understanding of R. H. I. C. ; taken for granted • femtoscopy the only way to confirm x-p correlations – impt check x 2 -p correlation: yes x -p correlation: yes Non-flow possibilities • cooling, thermally (not collectively) expanding source • combo of x-t and t-p correlations t • hot core surrounded by cool shell • important ingredient of Buda-Lund hydro picture e. g. Csörgő & Lörstad PRC 54 1390 (1996) May 2005 The Berkeley School - Femtoscopy - malisa x 2 -p correlation: yes x -p correlation: no

28 • flow-dominated “models” can reproduce soft -sector x-space observables • imply short timescales • however, are we on the right track? [flow] • puzzles? check your assumptions! • look for flow’s “special signature” x -p correlation • In flow pictures, low-p. T particles emitted closer to source’s center (along “out”) • non-identical particle correlations (FSI at low v) probe: • (x 1 -x 2)2 (as does HBT) • x 1 -x 2 T K p. T p [click for more details on non-id correlations] May 2005 F. Retiere & MAL, Csanád, nucl-th/0312024 Csörgő, Lörstad nucl-th/0311102 and nucl-th/0310040 The Berkeley School - Femtoscopy - malisa

29 x (fm) QM 02 T x (fm) T • extracted shift in emission point x 1 -x 2 w/ flow-dominated blastwave • consistent In flow pictures, low-p. T particles emitted closer to source’s center (along “out”) • non-identical particle correlations (FSI at low v) probe: • (x 1 -x 2)2 (as does HBT) • x 1 -x 2 May 2005 The Berkeley School - Femtoscopy - malisa A. Kisiel (STAR) QM 04

Motivation Formalism Experiment Trends Models Strong flow confirmed by all expts. . . LPSW(05) - DATA in color-- experimentalist’s plot what agreement!! (what agreement? ) May 2005 The Berkeley School - Femtoscopy - malisa 30

Motivation Formalism Experiment Trends Models Strong flow confirmed by all expts. . . Central (~10%) Au. Au (Pb. Pb) collisions at y~0 May 2005 The Berkeley School - Femtoscopy - malisa 31

Motivation Formalism Experiment Trends Models Another implication of strong flow: ~m. T scaling May 2005 The Berkeley School - Femtoscopy - malisa 32

Motivation Formalism Experiment Trends Models Some longitudinal systematics ce n a i r a v i n t-i on c n i te s i s nt th i w s o bo ith w t en ar v -in ce n a t os o b t s i ns o c May 2005 PHOBOS nucl-ex/0410022 The Berkeley School - Femtoscopy - malisa 33

34 “Dynamic” BI without “Chemical” BI ? Only femtoscopy can tell! beam May 2005 The Berkeley School - Femtoscopy - malisa

35 “Dynamic” BI without “Chemical” BI ? Only femtoscopy can tell! beam May 2005 The Berkeley School - Femtoscopy - malisa

Motivation Formalism Experiment Trends Models Greater detail - -p correlations @ AGS C sizes and offsets in impact parameter and longitudinal E 877, Miskowiec CRIS’ 98 directions nucl-ex/9808003 p- 10 fm b q. X (Ge. V/c) q. Y (Ge. V/c) z May 2005 The Berkeley School - Femtoscopy - malisa q. Z (Ge. V/c) 36

Summary - very brief. More in Friday’s discussion May 2005 The Berkeley School - Femtoscopy - malisa 37

Summary - very brief. More in Friday’s discussion • Part I – space-time THE special aspect of our field – systematics pass sanity check • Data show remarkable consistency R = 1. 2 (fm) • A • HUGE range of systematics, b (mag and direction), p. T, m 11/3 m 2, y, AB – – size shape orientation in 3 D space detailed dynamic substructure in all directions including shifts • At a given s, flow-dominated scenario strongly indicated. Can work (Blast Wave) • (Unfortunately? ) 2 decades of experimental effort over 2 decades of s – very little changes – scaling with final multiplicity, not A. . . progress? May 2005 The Berkeley School - Femtoscopy - malisa 38

39 final words (for today) • We are measuring system geometry • Space and time geometry (in detail) hardly changes AGS RHIC • This astounding fact is the 0 th HBT Puzzle, and much more important/troubling than the 1 st Puzzle (model failures) – generic expectation: entropy & latent heat / “softest point” • Given the importance of spacetime to RHI and QGP, this deserves our attention, despite its being a wart on otherwise “perfect” story May 2005 The Berkeley School - Femtoscopy - malisa