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Azimuthally-sensitive HBT in STAR

Explore the dynamics of noncentral collisions through azimuthally-sensitive interferometry and previous STAR results at RHIC. Discuss hydrodynamic predictions, early dense stages, and system response. Analyze the effect of dilute and hadronic stages on v2 and HBT radii. Investigate freezeout shapes and symmetries in the emission function.

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Azimuthally-sensitive HBT in STAR

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  1. Azimuthally-sensitive HBT in STAR Mike Lisa Ohio State University • Motivation • Noncentral collision dynamics • Azimuthally-sensitive interferometry & previous results • STAR results • Hydrodynamic predictions for RHIC and “LHC” • Summary Mike Lisa - XXXII ISMD - Alushta, Ukraine

  2. Central collision dynamics @ RHIC • Hydrodynamics reproduces p-space aspects of particle emission up to pT~2GeV/c (99% of particles) hopes of exploring the early, dense stage Mike Lisa - XXXII ISMD - Alushta, Ukraine Heinz & Kolb, hep-th/0204061

  3. Central collision dynamics @ RHIC • Hydrodynamics reproduces p-space aspects of particle emission up to pT~2GeV/c (99% of particles) hopes of exploring the early, dense stage • x-space is poorly reproduced • model source lives too long and disintegrates too slowly? • Correct dynamics signatures with wrong space-time dynamics? • Turn to richer dynamics of non-central collisions for more detailed information Mike Lisa - XXXII ISMD - Alushta, Ukraine Heinz & Kolb, hep-th/0204061

  4. Noncentral collision dynamics • hydro reproduces v2(pT,m) (details!) @ RHIC for pT < ~1.5 GeV/c • system response  EoS • early thermalization indicated Heinz & Kolb, hep-ph/0111075 hydro evolution • Dynamical models: • x-anisotropy in entrance channel  p-space anisotropy at freezeout • magnitude depends on system response to pressure Mike Lisa - XXXII ISMD - Alushta, Ukraine

  5. Effect of dilute stage later hadronic stage? hydro evolution • hydro reproduces v2(pT,m) (details!) @ RHIC for pT < ~1.0 GeV/c • system response  EoS • early thermalization indicated • dilute hadronic stage (RQMD): • little effect on v2 @ RHIC Mike Lisa - XXXII ISMD - Alushta, Ukraine Teaney, Lauret, & Shuryak, nucl-th/0110037

  6. Effect of dilute stage later hadronic stage? hydro only hydro+hadronic rescatt STAR PHENIX hydro evolution • hydro reproduces v2(pT,m) (details!) @ RHIC for pT < ~1.5 GeV/c • system response  EoS • early thermalization indicated • dilute hadronic stage (RQMD): • little effect on v2 @ RHIC • significant (bad) effect on HBT radii calculation: Soff, Bass, Dumitru, PRL 2001 Mike Lisa - XXXII ISMD - Alushta, Ukraine

  7. Effect of dilute stage later hadronic stage? hydro evolution • hydro reproduces v2(pT,m) (details!) @ RHIC for pT < ~1.5 GeV/c • system response  EoS • early thermalization indicated • dilute hadronic stage (RQMD): • little effect on v2 @ RHIC • significant (bad) effect on HBT radii • related to timescale? - need more info Mike Lisa - XXXII ISMD - Alushta, Ukraine Teaney, Lauret, & Shuryak, nucl-th/0110037

  8. Effect of dilute stage later hadronic stage? in-plane-extended out-of-plane-extended hydro evolution • hydro reproduces v2(pT,m) (details!) @ RHIC for pT < ~1.5 GeV/c • system response  EoS • early thermalization indicated • dilute hadronic stage (RQMD): • little effect on v2 @ RHIC • significant (bad) effect on HBT radii • related to timescale? - need more info • qualitative change of freezeout shape!! • important piece of the puzzle! Mike Lisa - XXXII ISMD - Alushta, Ukraine Teaney, Lauret, & Shuryak, nucl-th/0110037

  9. Possible to “see” via HBT relative to reaction plane? fp=90° Rside (small) Rside (large) fp=0° • for out-of-plane-extended source, expect • large Rside at 0 • small Rside at 90 2nd-order oscillation Rs2 [no flow expectation] fp Mike Lisa - XXXII ISMD - Alushta, Ukraine

  10. “Traditional HBT” - cylindrical sources K Rout Rside Decompose q into components: qLong: in beam direction qOut : in direction of transverse momentum qSide:  qLong & qOut (beam is into board) Mike Lisa - XXXII ISMD - Alushta, Ukraine

  11. Anisotropic sources Six HBT radii vs f side y K out • Source in b-fixed system: (x,y,z) • Space/time entangled in pair system (xO,xS,xL) fp x b ! • explicit and implicit (xmxn(f)) dependence on f Mike Lisa - XXXII ISMD - Alushta, Ukraine Wiedemann, PRC57 266 (1998).

  12. Symmetries of the emission function I. Mirror reflection symmetry w.r.t. reactionplane (for spherical nuclei):  with II. Point reflection symmetry w.r.t. collision center (equal nuclei):  with Heinz, Hummel, MAL, Wiedemann, nucl-th/0207003 Mike Lisa - XXXII ISMD - Alushta, Ukraine

  13. Fourier expansion of HBT radii @ Y=0 Insert symmetry constraints of spatial correlation tensor into Wiedemann relations and combine with explicit F-dependence: Note: These most general forms of the Fourier expansions for the HBT radii are preserved when averaging the correlation function over a finite, symmetric window around Y=0. Relations between the Fourier coefficients reveal interplay between flow and geometry, and can help disentangle space and time Mike Lisa - XXXII ISMD - Alushta, Ukraine Heinz, Hummel, MAL, Wiedemann, nucl-th/0207003

  14. Anisotropic HBT results @ AGS (s~2 AGeV) out side long 40 R2 (fm2) 20 os ol sl 10 0 -10 0 0 0 180 180 180 fp (°) Au+Au 2 AGeV; E895, PLB 496 1 (2000) xside xout K fp = 0° • strong oscillations observed • lines: predictions for static (tilted) out-of-plane extended source  consistent with initial overlap geometry Mike Lisa - XXXII ISMD - Alushta, Ukraine

  15. Meaning of Ro2(f) and Rs2(f) are clearWhat about Ros2(f) ? out side long xside 40 R2 (fm2) xside xside xside xside xside xside xout xout xout xout xout xout xout 20 K os ol sl 10 K K K K K K 0 -10 0 0 0 180 180 180 No access to 1st-order oscillations in STAR Y1 fp (°) Au+Au 2 AGeV; E895, PLB 496 1 (2000) fp = 0° fp ~45° • Ros2(f) quantifies correlation between xout and xside • No correlation (tilt) b/t between xout and xside at fp=0° (or 90°) • Strong (positive) correlation when fp=45° • Phase of Ros2(f) oscillation reveals orientation of extended source Mike Lisa - XXXII ISMD - Alushta, Ukraine

  16. Indirect indications of x-space anisotropy @ RHIC dashed solid T (MeV) 135  20 100  24 0(c) 0.52  0.02 0.54  0.03 a (c) 0.09  0.02 0.04  0.01 S2 0.0 0.04  0.01 • v2(pT,m) globally well-fit by hydro-inspired “blast-wave” temperature, radial flow consistent with fits to spectra  anisotropy of flow boost spatial anisotropy (out-of-plane extended) Mike Lisa - XXXII ISMD - Alushta, Ukraine STAR, PRL 87 182301 (2001)

  17. STAR data Au+Au 130 GeV minbias full blastwave consistent with R(pT), K-p • significant oscillations observed • blastwave with ~ same parameters as used to describe spectra & v2(pT,m) • additional parameters: • R = 11 fm •  = 2 fm/c !! preliminary Mike Lisa - XXXII ISMD - Alushta, Ukraine

  18. STAR data Au+Au 130 GeV minbias full blastwave no flow anisotropy consistent with R(pT), K-p no spatial anisotropy • significant oscillations observed • blastwave with ~ same parameters as used to describe spectra & v2(pT,m) • additional parameters: • R = 11 fm •  = 2 fm/c !! preliminary • both flow anisotropy and source shape contribute to oscillations, but… • geometry dominates dynamics • freezeout source out-of-plane extended fast freeze-out timescale ! Mike Lisa - XXXII ISMD - Alushta, Ukraine

  19. Azimuthal HBT: hydro predictions • RHIC (T0=340 MeV @ t0=0.6 fm) • Out-of-plane-extended source (but flips with hadronic afterburner) • flow & geometry work together to produce HBT oscillations • oscillations stable with KT (note: RO/RS puzzle persists) Heinz & Kolb, hep-th/0204061 Mike Lisa - XXXII ISMD - Alushta, Ukraine

  20. Azimuthal HBT: hydro predictions • RHIC (T0=340 MeV @ t0=0.6 fm) • Out-of-plane-extended source (but flips with hadronic afterburner) • flow & geometry work together to produce HBT oscillations • oscillations stable with KT • “LHC” (T0=2.0 GeV @ t0=0.1 fm) • In-plane-extended source (!) • HBT oscillations reflect competition between geometry, flow • low KT: geometry • high KT: flow sign flip Heinz & Kolb, hep-th/0204061 Mike Lisa - XXXII ISMD - Alushta, Ukraine

  21. HBT(φ) Results – 200 GeV STAR PRELIMINARY • Oscillations similar to those measured @ 130GeV • 20x more statistics explore systematics in centrality, kT • much more to come… Mike Lisa - XXXII ISMD - Alushta, Ukraine

  22. Summary • Quantitative understanding of bulk dynamics crucial to extracting real physics at RHIC • p-space - measurements well-reproduced by models • anisotropy  system response to compression (EoS) • probe via v2(pT,m) • x-space - generally not well-reproduced • anisotropy  evolution, timescale information, geometry / flow interplay • Azimuthally-sensitive HBT: correlating quantum correlation with bulk correlation • reconstruction of full 3D source geometry • Freezeout geometry out-of-plane extended • early (and fast) particle emission ! • consistent with blast-wave parameterization of v2(pT,m), spectra, R(pT), K-p • With more detailed information, “RHIC HBT puzzle” deepens • what about hadronic rescattering stage? - “must” occur, or…? • does hydro reproduce t or not?? • ~right source shape via oscillations, but misses RL(mT) • Models of bulk dynamics severely (over?)constrained Mike Lisa - XXXII ISMD - Alushta, Ukraine

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