1. mike lisa - austin texas - 10 sept 20071 Mike Lisa Ohio State University *femtoscopy (fem-ta-skö-pee) noun Measurement of spatial scales at the fermi level with 2-particle correlations Non-trivially related to the “HBT effect” invented to measure stellar scales Femtoscopy in relativistic heavy ion collisions: a (too-universal) dynamical picture

2. mike lisa - austin texas - 10 sept 20072 Femtoscopy in relativistic heavy ion collisions: a (too-universal) dynamical picture Reminder: why heavy ions (@ RHIC & beyond)

3. mike lisa - austin texas - 10 sept 20073 Femtoscopy in relativistic heavy ion collisions: a (too-universal) dynamical picture Reminder: why heavy ions (@ RHIC & beyond) femtoscopy: relevance and method

4. mike lisa - austin texas - 10 sept 20074 Femtoscopy in relativistic heavy ion collisions: a (too-universal) dynamical picture Reminder: why heavy ions (@ RHIC & beyond) femtoscopy: relevance and method detailed systematics & what it tells us pT, mT, y,   s, dN/dy, A+B “exotic beam factory”

5. mike lisa - austin texas - 10 sept 20075 Femtoscopy in relativistic heavy ion collisions: a (too-universal) dynamical picture Reminder: why heavy ions (@ RHIC & beyond) femtoscopy: relevance and method detailed systematics & what it tells us pT, mT, y,   s, dN/dy, A+B “exotic beam factory” excitation function, comparison to “simpler” (?) systems in progress Summary

6. mike lisa - austin texas - 10 sept 20076 Introduction: Heavy ions & bulk matter

7. mike lisa - austin texas - 10 sept 20077 RHIC BRAHMS PHOBOS PHENIX STAR AGS TANDEMS NuclearParticle

8. mike lisa - austin texas - 10 sept 20078 Why heavy ion collisions? NuclearParticle STAR ~500 Collaborators

9. mike lisa - austin texas - 10 sept 20079 2 types (?) of collisions... looks like fun... looks like a mess...

10. mike lisa - austin texas - 10 sept 200710 A dynamical but crude view of the collision In this model, insufficient re-interactions c/o UrQMD Collaboration, Frankfurt

11. mike lisa - austin texas - 10 sept 200711 A dynamical but crude view of the collision In this model, insufficient re-interactions

12. mike lisa - austin texas - 10 sept 200712 R.H.I.C. defined... collision of nuclei sufficiently large that nuclear details unimportant distinct from nuclear or particle physics “Geranium on Linoleum” sufficiently large for meaningful bulk & thermodynamic quantities non-trivial spatial scales & geometry drive bulk dynamics (e.g. flow) how big is “sufficient” ? important reference issue

13. mike lisa - austin texas - 10 sept 200713 phase structure of bulk system: driving symmetries long-range collective behaviour “new” physics [superfluidity in l-He] relevance of meaningful EoS

14. mike lisa - austin texas - 10 sept 200714 The four elements from 400 BC to 2000AD 400 BC : all creation EarthFire Air Water ?

15. mike lisa - austin texas - 10 sept 200715 RHIC energies: the first quantitative success of hydro direct access to EoS (phase transitions, lattice, etc.) EoS: P versus  versus n (Heinz et al)

16. mike lisa - austin texas - 10 sept 200716 Microexplosions Femtoexplosions  10 17 J/m 3 5 GeV/fm 3 = 10 36 J/m 3 ss0.1  J 1  J T10 6 K200 MeV = 10 12 K rate10 18 K/sec10 35 K/s energy quickly deposited enter plasma phase expand hydrodynamically cool back to original phase do geometric “postmortem” & infer momentum

17. mike lisa - austin texas - 10 sept 200717 MicroexplosionsFemtoexplosions ss0.1  J 1  J  10 17 J/m 3 5 GeV/fm 3 = 10 36 J/m 3 T10 6 K200 MeV = 10 12 K rate10 18 K/sec10 35 K/s energy quickly deposited enter plasma phase expand hydrodynamically cool back to original phase do geometric “postmortem” & infer momentum

18. mike lisa - austin texas - 10 sept 200718 Impact parameter & Reaction plane b = 0  “central collision” many particles produced “peripheral collision” fewer particles produced

19. mike lisa - austin texas - 10 sept 200719 Impact parameter & Reaction plane b = 0  “central collision” many particles produced “peripheral collision” fewer particles produced

20. mike lisa - austin texas - 10 sept 200720 How do semi-central collisions evolve? 1) Superposition of independent p+p: momenta pointed at random relative to reaction plane

21. mike lisa - austin texas - 10 sept 200721 How do semi-central collisions evolve? 1) Superposition of independent p+p: 2) Evolution as a bulk system momenta pointed at random relative to reaction plane high density / pressure at center “zero” pressure in surrounding vacuum Pressure gradients (larger in-plane) push bulk “out”  “flow” more, faster particles seen in-plane

22. mike lisa - austin texas - 10 sept 200722 How do semi-central collisions evolve? 1) Superposition of independent p+p: 2) Evolution as a bulk system momenta pointed at random relative to reaction plane Pressure gradients (larger in-plane) push bulk “out”  “flow” more, faster particles seen in-plane N  -  RP (rad) 0  /2   /43  /4 N  -  RP (rad) 0  /2   /43  /4

23. mike lisa - austin texas - 10 sept 200723 Azimuthal distributions at RHIC STAR, PRL90 032301 (2003) b ≈ 4 fm “central” collisions b ≈ 6.5 fm midcentral collisions

24. mike lisa - austin texas - 10 sept 200724 Azimuthal distributions at RHIC STAR, PRL90 032301 (2003) b ≈ 4 fm b ≈ 6.5 fm b ≈ 10 fm peripheral collisions

25. mike lisa - austin texas - 10 sept 200725 Wow ! Sensitivity to early EoS! STAR, PRL90 032301 (2003) Hydro: P. Huovinen, P. Kolb, U. Heinz

26. mike lisa - austin texas - 10 sept 200726 It’s not just good, it’s... perfect!

27. mike lisa - austin texas - 10 sept 200727 Hydromania - careful... single-point agreement - red flag in H.I. physics STAR, PRL86 402 (2001)

28. mike lisa - austin texas - 10 sept 200728 Beyond press releases The detailed work now underway is what can probe & constrain sQGP properties It is probably not press-release material... (...but, hey, you’ve already got your coffee mug) ature of EoS unde estigation ; agreement wi data might be accidental ; viscous hydrodynamics under development ; assumption of thermalization in question sensitivity to modeling of initial state, under intense study

29. mike lisa - austin texas - 10 sept 200729 Femtoscopy

30. mike lisa - austin texas - 10 sept 200730 More direct access to geometric substructure?

31. mike lisa - austin texas - 10 sept 200731 Simple picture: probing source geometry through interferometry Measurable! F.T. of pion source Creation probability  (x,p) = U * U 5 fm 1 m  source  (x) r1r1 r2r2 x1x1 x2x2 p1p1 p2p2 The Bottom line… if a pion is emitted, it is more likely to emit another pion with very similar momentum if the source is small experimentally measuring this enhanced probability: quite challenging

32. mike lisa - austin texas - 10 sept 200732 Correlation functions for different sized systems C 2 (Q inv ) Q inv (GeV/c) STAR p+p R ~ 1 fm d+Au R ~ 2 fm Au+Au R ~ 6 fm Different colliding systems studied at RHIC Interferometry probes the smallest scales ever measured ! nucl-ex/0505014

33. mike lisa - austin texas - 10 sept 200733 q out q side q long High-statistics: beyond simple scales R side R long R out x1x1 x2x2 p1p1 p2p2 Two-particle interferometry: p-space separation  space-time separation R side R out Pratt-Bertsch (“out-side-long”) decomposition designed to help disentangle space & time source s p (x) = homogeneity region [Sinyukov(95)]  connections with “whole source” always model-dependent

34. mike lisa - austin texas - 10 sept 200734 Femtoscopic information xaxa xbxb papa pbpb xaxa xbxb papa pbpb Distillation of ~10 5 datapoints in correlation function into ~5 numbers often: S(r) assumed 3D Gaussian Au+Au: central collisions C(Q out ) C(Q side ) C(Q long ) 3 “radii” by using 3-D vector q STAR Collab PRC 2004 Koonin ‘77; Pratt ‘84

35. mike lisa - austin texas - 10 sept 200735 “”“” Rischke, Gyulassy, NP A 608 (1996) 479 R out /R side R(√S NN ) – simple signal ? Generic expectation pre-RHIC turnon

36. mike lisa - austin texas - 10 sept 200736 “”“” Rischke, Gyulassy, NP A 608 (1996) 479 R out /R side R(√S NN, b, N part, A, B, m T, y, , PID) No glaring signal in simple measures The „real” (experimentalist’s) „puzzle” mass |b| pTpT R(√S NN ) – simple signal ? Generic expectation pre-RHIC turnon

37. mike lisa - austin texas - 10 sept 200737 Wide range of systematics @ RHIC

38. mike lisa - austin texas - 10 sept 200738 Why do the radii fall with increasing momentum ??

39. mike lisa - austin texas - 10 sept 200739 Spectra v2v2 HBT measure explosive pattern of the thermalized bulk matter (low-pT) hydro expectation (off-center collision) collective p T component: m*v T

40. mike lisa - austin texas - 10 sept 200740 Spectra v2v2 HBT measure explosive pattern of the thermalized bulk matter (low-pT) “elliptic flow”

41. mike lisa - austin texas - 10 sept 200741 Spectra v2v2 HBT measure explosive pattern of the thermalized bulk matter (low-pT) femtoscopy probes x-p substructure Amount of flow consistent with p-space nucl-th/0312024 Huge, diverse systematics consistent with this substructure nucl-ex/0505014 “homogeneity regions”

42. mike lisa - austin texas - 10 sept 200742 Comparison to “perfect” hydro calculations LPSW(05) “embarrassing” experimental consistency considerable physics/model sensitivity R out too big (too long emission time?) R long too big (too long evolution time?) R side too small (?) BlastWave  ~9 fm/c hydro:  ~15 fm/c

43. mike lisa - austin texas - 10 sept 200743 Time, (isotropic) pressure gradients and (isotropic) flow old figures hydro models: pressure too low & time too long?? impacts EoS / “soft point” need more info to confirm (model-dep)

44. mike lisa - austin texas - 10 sept 200744 Strongly-interacting 6 Li released from an asymmetric trap O’Hara, et al, Science 298 2179 (2002) What can we learn? ? Hydro:Huovinen, Kolb, Heinz Time, (anisotropic) pressure gradients and (anisotropic) flow momentum only (  dt ) space! (& time)

45. mike lisa - austin texas - 10 sept 200745 big R S small R S

46. mike lisa - austin texas - 10 sept 200746 central collisions mid-central collisions peripheral collisions

47. mike lisa - austin texas - 10 sept 200747 The rule of 2  initial =  final STAR PRL93 012301 (2004) R final /R initial 1 2 2.5 1.5 1002003004000 STAR PRC71 044906 (2005) @RHIC Initial size/shape estimated by Glauber calculation ~ x2 size increase~ 1/2 shape reduction angle-integrated angle-differential harder EoS (no latent heat) likely required

48. mike lisa - austin texas - 10 sept 200748 Global picture should include more than ... K 0 s - K 0 s STAR PRC74 054902

49. mike lisa - austin texas - 10 sept 200749 Global picture should include more than ... K 0 s - K 0 s  -p STAR PRC 74 (2006) 064906

50. mike lisa - austin texas - 10 sept 200750 Global picture should include more than ... K 0 s - K 0 s  -p p(bar)-p(bar) centrality dependence ok but more... 0-10% 30-80% Fits are kernel-filtered Gaussian sources Typically one considers “contamination” in terms of uncorrelated pairs (mid-id, weak decays,...) measured CF is just “diluted” true CF (e.g. “ ”)

51. mike lisa - austin texas - 10 sept 200751 Correlated ‘contamination’ in (anti-)baryon correlations STAR, PRC74 (2006) 064906 Crucial to extract reliable source estimates H. Gos

52. mike lisa - austin texas - 10 sept 200752 Global geometric substructure of explosive source All signatures of explosive flow observed momentum-space-only (spectra, v2) falling pion “radii” with mT Spectra v2v2 HBT slow  emission fast  emission

53. mike lisa - austin texas - 10 sept 200753 Global geometric substructure of explosive source All signatures of explosive flow observed momentum-space-only (spectra, v2) falling pion “radii” with mT falling other “radii” with mT  emission region K emission region R (fm) m T (GeV/c) But there is something more...

54. mike lisa - austin texas - 10 sept 200754 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 PRC54 1390 (1996) t Each scenario generates x-p correlations but…  x 2  -p correlation:yes  x  -p correlation:yes  x 2  -p correlation:yes  x  -p correlation:no  x 2  -p correlation:yes  x  -p correlation:no Beyond size-momentum correlations

55. mike lisa - austin texas - 10 sept 200755 In flow pictures (BlastWave), low-p T particles emitted closer to source’s center non-identical particle correlations (FSI at low  v) probe:  (x 1 -x 2 ) 2  (as does HBT)  x 1 -x 2  F. Retiere & MAL, PRC70 044907 (2004) pTpT TT K p 

56. mike lisa - austin texas - 10 sept 200756 Kaon – pion correlations: dominated by Coulomb interaction Smaller source  stronger (anti)correlation K-p correlation well-described by: Blast wave with same parameters as spectra, HBT But with non-identical particles, we can access more information… STAR PRL 91 (2003) 262302

57. mike lisa - austin texas - 10 sept 200757 Initial idea: probing emission-time ordering Catching up: cos  0 long interaction time strong correlation Ratio of both scenarios allow quantitative study of the emission asymmetry Moving away: cos  0 short interaction time weak correlation Crucial point: kaon begins farther in “out” direction (in this case due to time-ordering) purple K emitted first green  is faster purple K emitted first green  is slower e.g. Lednicky et al Phys. Lett. B373:30–34, 1996

58. mike lisa - austin texas - 10 sept 200758 Initial idea: probing emission-time ordering Catching up: cos  0 long interaction time strong correlation Ratio of both scenarios allow quantitative study of the emission asymmetry Moving away: cos  0 short interaction time weak correlation Crucial point: kaon begins farther in “out” direction (in this case due to time-ordering) purple K emitted first green  is faster purple K emitted first green  is slower STAR PRL 91 (2003) 262302 e.g. Lednicky et al Phys. Lett. B373:30–34, 1996 Mass-ordering observed in agreement with blast substructure  emission region K emission region

59. mike lisa - austin texas - 10 sept 200759 Sidetrack: phaseshifts

60. mike lisa - austin texas - 10 sept 200760 Systematic mapping ++ -- K+K+ K-K- K0SK0S p pp  ++ --  -  K+K+  K-K-  --K0SK0S  p pp     central vs peripheral !!!

61. mike lisa - austin texas - 10 sept 200761 Parallel focus - vary kernel parameters, too xaxa xbxb papa pbpb xaxa xbxb papa pbpb ++ -- K+K+ K-K- K0SK0S p pp  ++ --  -  K+K+  K-K-  --K0SK0S  p pp     “exotic beams”

62. mike lisa - austin texas - 10 sept 200762 Parallel focus - vary kernel parameters, too First-ever  p- , p- ,  p-  correlations Consistency from baryon sector for flow-generated x-p correlations Extraction of real/imaginary  p- , p-  scattering lengths from CF !! similarly for K 0 S important new physics direction STAR, PRC 2006 xaxa xbxb papa pbpb xaxa xbxb papa pbpb

63. mike lisa - austin texas - 10 sept 200763 F. Retiere WPCF05 see talk of M. Bysersky / M. Sumbera

64. mike lisa - austin texas - 10 sept 200764 Another first -- femtoscopy in p+p collisions in same detector (same systematics) as in A+A

65. mike lisa - austin texas - 10 sept 200765 p+p: A clear reference system?

66. mike lisa - austin texas - 10 sept 200766 femtoscopy in p+p @ STAR DELPHI Z 0 decay @ LEP m, m T (GeV) R (fm) R Z (fm) hep-ph/0108194   K p  STAR preliminary m T (GeV) 1. Heisenberg uncertainty? e.g. G. Alexander “plausible” in z-direction unlikely in transvrse 2. String fragmentation? (Lund) p T dependence maybe (??) mass dependence probably no [Andersson, Moriond 2000] 3. Resonance effects? e.g. Wiedemann & Heinz ‘97 maybe, but presumably significantly different effect than for Au+Au under investigation Zbigniew Chajecki QM05 p+p and A+A measured in same experiment great opportunity to compare physics what causes pT-dependence in p+p? same cause as in A+A?

67. mike lisa - austin texas - 10 sept 200767 femtoscopy in p+p @ STAR DELPHI Z 0 decay @ LEP m, m T (GeV) R (fm) R Z (fm) hep-ph/0108194   K p  STAR preliminary m T (GeV) 1. Heisenberg uncertainty? 2. String fragmentation? (Lund) 3. Resonance effects? Zbigniew Chajecki QM05 p+p and A+A measured in same experiment great opportunity to compare physics what causes pT-dependence in p+p? same cause as in A+A?  d+Au : Rlong doesn’t change with centrality flow not expected in such a small system as p+p e.g. Shuryak: hep-ph/0405066  Csorgo et al.: Buda-Lund treatment of p+p collision as bulk system (w/ temperature gradients) hep-ph/0406042 R OUT R SIDE R LONG m T -m (GeV) 1/(2  m T )d 2 n/(dm T dy)  K p m T (GeV) 4. Bulk system („hydro”) in pp? b

68. mike lisa - austin texas - 10 sept 200768 Surprising („puzzling”) scaling  All p T (m T ) dependences of 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 Ratio of (AuAu, CuCu, dAu) HBT radii by pp A. Bialasz (ISMD05): I personally feel that its solution may provide new insight into the hadronization process of QCD

69. mike lisa - austin texas - 10 sept 200769 Summary Diverse systematic femtoscopic program at RHIC Naive dramatic expectations disappointed (“puzzle”) Sanity check : strong correlation with initial state  Explosive dominance extensively mapped in full geometric substructure shape - 3D, long-range tail (imaging) size-momentum correlations [incl various FSI combos] position-momentum correlations [unique information] exotic correlations: substructure of space-time dynamics of  Physics sensitivity: indications for small latent heat (no “softest point”) low-energy QCD connection: H.I.C. as “exotic beam” factory Crucial question: apples::apples comparison of geometry hadronic/nuclear collisions similarity of p+p & Au+Au (& d+Au) : “deep” or coincidental? R(√S NN, b, N part, A, B, m T, y, , PID 1, PID 2 )

70. mike lisa - austin texas - 10 sept 200770 OPAL @ LEP CERN-PH-EP/2007-02