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Azimuthally-sensitive HBT (asHBT) in Au+Au collisions at s NN =200 GeV

Azimuthally-sensitive HBT (asHBT) in Au+Au collisions at s NN =200 GeV. Zero-th – order information from. ^. Mike Lisa, Ohio State University for the STAR Collaboration. motivation – why study asHBT @ RHIC? BlastWave parameterization of freeze-out fits/predictions @ 130 GeV

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Azimuthally-sensitive HBT (asHBT) in Au+Au collisions at s NN =200 GeV

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  1. Azimuthally-sensitive HBT (asHBT) inAu+Au collisions at sNN=200 GeV Zero-th – order information from ^ Mike Lisa, Ohio State University for the STAR Collaboration • motivation – why study asHBT @ RHIC? • BlastWave parameterization of freeze-out • fits/predictions @ 130 GeV • sensitivity of asHBT to F.O. shape • asHBT in Au+Au collisions at s NN=200 GeV • RP/binning resolution correction • radii vs centrality, kT,  • physics implications • Summary 2nd Warsaw Meeting on Correlations and Resonances

  2. Already a problem with “traditional” HBT @ RHIC… dN/dt time • p-space observables well-understood within hydrodynamic framework • → hope of understanding early stage • x-space observables not well-reproduced • correct dynamical signatures with incorrect dynamic evolution? • Too-large timescales modeled? • emission/freezeout duration (RO/RS) • evolution duration (RL) Soff, Bass, Dumitru Heinz & Kolb, hep-ph/0204061 2nd Warsaw Meeting on Correlations and Resonances

  3. Already a problem with “traditional” HBT @ RHIC… hydro only hydro+hadronic rescatt dN/dt STAR PHENIX time • p-space observables well-understood within hydrodynamic framework • → hope of understanding early stage • x-space observables not well-reproduced • correct dynamical signatures with incorrect dynamic evolution? • Too-large timescales modeled? • emission/freezeout duration (RO/RS) • evolution duration (RL) “Realistically” treating FO with hadronic afterburner makes it worse 2nd Warsaw Meeting on Correlations and Resonances

  4. … so why study (more complicated) asHBT ? • sensitive to interplay b/t anisotropic geometry & dynamics/evolution Kolb & Heinz, Phys. Lett. B542 216 (2002) 2nd Warsaw Meeting on Correlations and Resonances

  5. … so why study (more complicated) asHBT ? P. Kolb and U. Heinz, hep-ph/0204061 P. Kolb, nucl-th/0306081 “radial flow” “elliptic flow” • sensitive to interplay b/t anisotropic geometry & dynamics/evolution • “broken symmetry” for b0 → more detailed, important physics information • another handle on dynamical timescales – likely impt in HBT puzzle 2nd Warsaw Meeting on Correlations and Resonances

  6. Freeze-out anisotropy as an evolution “clock” later hadronic stage? RS small fp=90° Teaney et al, nucl-th0110037 P. Kolb and U. Heinz, hep-ph/0204061 in-plane-extended hydro only hydro+hadronic rescatt RS big R.P. fp=0° STAR PHENIX Soff, Bass, Dumitru, PRL 2001 out-of-plane-extended Teaney et al, nucl-th0110037 Teaney, Lauret, Shuryak, nucl-th/0110037 hydro evolution • anisotropic pressure gradients • → preferential in-plane flow (v2) • → evolution towards in-plane shape • FO sensitive to evolution duration 0 • dilute (hadronic) stage • little effect on p-space at RHIC • significant (bad) effect on HBT radii • related to timescale • qualitative change in FO • FO from asHBT? 2nd Warsaw Meeting on Correlations and Resonances

  7. Need a model of the freezeout- BlastWave R Teaney, Lauret & Shuryak, nucl-th/0110037 • BW: hydro-inspired parameterization of freezeout • longitudinal direction • infinite extent geometrically • boost-invariant longitudinal flow • Momentum space • temperature T • transverse rapidity boost ~ r • Schnedermann et al (’93): 2-parameter (T, max) “hydro-inspired” functional form to fit spectra. • Useful to extract thermal, collective energy azimuthally isotropic source model – let’s generalize for finite impact parameter … 2nd Warsaw Meeting on Correlations and Resonances

  8. Need a model of the freezeout- BlastWave RY 0 RX  0 • BW: hydro-inspired parameterization of freezeout • longitudinal direction • infinite extent geometrically • boost-invariant longitudinal flow • Momentum space • temperature T • transverse rapidity boost ~ r • coordinate space • transverse extents RX, RY • freezeout in proper time  • evolution duration 0 • emission duration  2nd Warsaw Meeting on Correlations and Resonances F. Retière & MAL, in preparation

  9. Need a model of the freezeout- BlastWave RY RX • BW: hydro-inspired parameterization of freezeout • longitudinal direction • infinite extent geometrically • boost-invariant longitudinal flow • Momentum space • temperature T • transverse rapidity boost ~ r • coordinate space • transverse extents RX, RY • freezeout in proper time  • evolution duration 0 • emission duration  7 parameters describing freezeout 2nd Warsaw Meeting on Correlations and Resonances F. Retière & MAL, in preparation

  10. BlastWave fits to published RHIC data central midcentral peripheral • pT spectra constrain (mostly) T, 0 2nd Warsaw Meeting on Correlations and Resonances F. Retière & MAL, in preparation

  11. BlastWave fits to published RHIC data Rout Rout Rside Rside R=9 fm R=12 fm R=18 fm Rlong Rlong • pT spectra constrain (mostly) T, 0 • (traditional) HBT radii constrain R, 0,  • depend also on T, 0 2nd Warsaw Meeting on Correlations and Resonances F. Retière & MAL, in preparation

  12. BlastWave fits to published RHIC data central midcentral peripheral • pT spectra constrain (mostly) T, 0 • (traditional) HBT radii constrain R, 0,  • depend also on T, 0 • imperfect fit (esp. PHENIX RS) 2nd Warsaw Meeting on Correlations and Resonances F. Retière & MAL, in preparation

  13. BlastWave fits to published RHIC data central midcentral peripheral • pT spectra constrain (mostly) T, 0 • (traditional) HBT radii constrain R, 0,  • depend also on T, 0 • imperfect fit (esp. PHENIX RS) • v2(pT,m) constrain RY/RX, a • reasonable centrality evolution • OOP extended source in non-central collisions ~ 2 fm/c with Bowler CC (Not this talk) 2nd Warsaw Meeting on Correlations and Resonances F. Retière & MAL, in preparation

  14. Minbias v2, asHBT @ 130 GeV STAR, PRL 87 182301 (2001) • v2(pT,m) globally well-fit by hydro-inspired “blast-wave” • a ~ 0.04, RY/RX ~ 1.05 • Minbias asHBT well-reproduced with same BlastWave from minbias v2(pT,m) • Ry = 11.4 fm • Rx = 10.8 fm • 0 = 8.3 fm/c •  = 0 ( → ~1.5 fm/c w/ Bowler CC)) • asHBT: geometry dominates dynamics • Source out-of-plane extended 2nd Warsaw Meeting on Correlations and Resonances

  15. So far RS small fp=90° RS big R.P. fp=0° • v2(pT,m) indicates OOP-extended FO source for non-central collisions • (confirmation from minbias asHBT) • Would rather “view” the geometry more directly • analyze asHBT in higher-statistics 200 GeV dataset (next…) • But… HBT radii depend on “everything” (T, 0, …) • can we extract FO shape from asHBT alone? 2nd Warsaw Meeting on Correlations and Resonances

  16. can we extract FO shape from asHBT alone?the BlastWave view out side • non-central collisions – all HBT radii exhibit 0th & 2nd - order oscillations (n>2 negligible) • characterize each kT bin with 7 numbers: R2os,0 = 0 by symmetry (*) long out-side (*) Heinz, Hummel, MAL, Wiedemann, Phys. Rev. C66 044903 (2002) 2nd Warsaw Meeting on Correlations and Resonances F. Retière & MAL, in preparation

  17. can we extract FO shape from asHBT alone?the BlastWave view • non-central collisions – all HBT radii exhibit 0th & 2nd - order oscillations (n>2 negligible) • characterize each kT bin with 7 numbers: • for fixed (RY2+RX2), increasing RY/RX • R2,0 unchanged • |R2,2| increases (sensitivity to FO shape) • both R2,0 and |R2,2| fall with pT • same dependence/mechanism?(flow-induced x-p correlations) • examine “normalized” oscillations R2,2/R2,0 2nd Warsaw Meeting on Correlations and Resonances F. Retière & MAL, in preparation

  18. FO shape from “normalized” oscillationsthe BlastWave view • no-flow scenario: independent of pT… U. Wiedemann PR C57 266 (1998) MAL, U. Heinz, U. Wiedemann PL B489 287 (2000) • in BW: this remains ~true even with flow(esp @ low pT) /2 2nd Warsaw Meeting on Correlations and Resonances F. Retière & MAL, in preparation

  19. FO shape from “normalized” oscillationsthe BlastWave view fixed  • no-flow scenario: independent of pT… U. Wiedemann PR C57 266 (1998) MAL, U. Heinz, U. Wiedemann PL B489 287 (2000) • in BW: this remains ~true even with flow(esp @ low pT) • independent of RY2+RX2 • independent of  (and 0) • ~independent of T (and 0) • estimate  from R2,2/ R2s,0 (=o,s,os) 2nd Warsaw Meeting on Correlations and Resonances F. Retière & MAL, in preparation

  20. asHBT at 200 GeV in STAR – R() vs centrality • 12 (!) -bins b/t 0-180 (kT-integrated) • 72 independent CF’s • clear oscillations observed in transverse radii of symmetry-allowed* type • Ro2, Rs2, Rl2 ~ cos(2) • Ros2 ~ sin(2) • centrality dependence reasonable • oscillation amps higher than 2nd-order ~ 0 • → extract 0th, 2nd Fourier coefficients vs kT with 4 -bin analysis (*) Heinz, Hummel, MAL, Wiedemann, Phys. Rev. C66 044903 (2002) 2nd Warsaw Meeting on Correlations and Resonances

  21. Correcting for finite -binning & RP-resolution • Reaction-plane estimation (from event-wise p-space anisotropy) is imperfect • → nth-order oscillations reduced by cos(n(m--R)) * m- m--R R * cos(nm) from flow analysis – e.g. Poskanzer & Voloshin Phys. Rev. C58 1671 (1998) 2nd Warsaw Meeting on Correlations and Resonances

  22. Correcting for finite -binning & RP-resolution • Reaction-plane estimation (from event-wise p-space anisotropy) is imperfect • → nth-order oscillations reduced by cos(n(m--R)) * •  bins have finite width  • → nth-order oscillations reduced by * cos(nm) from flow analysis – e.g. Poskanzer & Voloshin Phys. Rev. C58 1671 (1998) 2nd Warsaw Meeting on Correlations and Resonances

  23. Correcting for finite -binning & RP-resolution • Reaction-plane estimation (from event-wise p-space anisotropy) is imperfect • → nth-order oscillations reduced by cos(n(m--R)) * •  bins have finite width  • → nth-order oscillations reduced by • oscillations of what? • not the HBT radii • what is measured (and averaged/smeared) are pair number distributions N(q), D(q)[ C(q) = N(q) / D(q) ] * cos(nm) from flow analysis – e.g. Poskanzer & Voloshin Phys. Rev. C58 1671 (1998) 2nd Warsaw Meeting on Correlations and Resonances

  24. Correcting for finite -binning & RP-resolutionHeinz, Hummel, MAL, Wiedemann, Phys. Rev. C66 044903 (2002) “raw” corrected Fourier coefficients for a given q-bin. Fourier coefficients for a given q bin • correction factor for nth-order oscillations for the damping effects of • finite resolution in determining the mth-order event-plane • non-vanishing bin width () in the emission angle with respect to the event-plane (j) • ~ 30% effect on 2nd-order radius oscillations • ~0% change in mean values 2nd Warsaw Meeting on Correlations and Resonances

  25. asHBT at 200 GeV in STAR – R() vs kT midcentral collisions (20-30%) • Clear oscillations observed at all kT • extract 7 radius Fourier Coefficients(shown by lines) 2nd Warsaw Meeting on Correlations and Resonances

  26. Grand Data Summary – R2,n vs kT, centrality • One plot w/ relevant quantities from 2x5x3x4=120 3D CFs (*) • left: R2,0  “traditional” radii • usual kT, centrality dependence • right: R2,2 / R2,0 • reasonable centrality dependence • BW: sensitive to FO source shape (*) first STAR HBT paper: 10 CFs 2nd Warsaw Meeting on Correlations and Resonances

  27. Estimate of initial vs F.O. source shape FO = INIT RHIC1 [Kolb & Heinz] • estimate INIT from Glauber • from asHBT: • FO < INIT→ dynamic expansion • FO > 1 → source always OOP-extended • constraint on evolution time 2nd Warsaw Meeting on Correlations and Resonances

  28. A simple estimate – 0 from init and final “radial flow” P. Kolb, nucl-th/0306081 • BW → X, Y @ F.O. (X > Y) • hydro: flow velocity grows ~ t • From RL(mT): 0 ~ 9 fm/c • consistent picture • Longer or shorter evolution times • inconsistent • toy estimate: 0 ~ 0(BW)~ 9 fm/c • But need a real model comparison→ asHBT valuable “evolutionary clock” constraint for models 2nd Warsaw Meeting on Correlations and Resonances

  29. Summary • FO source shape a “clock” for system evolution • OOP-extended  earlier kinetic FO • further test of long-lived hadronic stage: OOPIP-extended source  inconsistent w/ data • BlastWave parameterization of FO at RHIC -- sNN=130 GeV • not perfect fit @ 130 GeV, but can provide some guidance/insight • “traditional HBT” in fit suggest short emission, evolution timescales • qualitatively supported by OOP from v2, minbias asHBT • Fourier decomposition of HBT radius oscillations • even with flow-induced x-p correlations, asHBT alone useful to estimate FO (R2u,2/ R2s,0) • asHBT @ sNN=200 GeV • 0th, 2nd-order oscillation amplitudes characterize -dependence of HBT radii • of type allowed by symmetry • centrality dependence reasonable • oscillations at all kT • OOP FO shape  “consistent” story of fast evolution (~9 fm/c) 2nd Warsaw Meeting on Correlations and Resonances

  30. To do… P.T.  soft spot in EOS & “stall” 2 fm/c 4 fm/c 6 fm/c 8 fm/c no P.T. in EOS  explosive P. Kolb, Ph.D. thesis (2002) • Us • finalize analysis/systematic errors • BW fits to final 200 GeV data (spectra, v2, asHBT) – does it hang consistently together? • Theorists • can satisfactory FO be reached faster (e.g. more explosive EoS)? • and can it be done consistently??? 2nd Warsaw Meeting on Correlations and Resonances

  31. To do… • Us • finalize analysis/systematic errors • BW fits to final 200 GeV data (spectra, v2, asHBT) – does it hang consistently together? • Theorists • can satisfactory FO be reached faster (e.g. more explosive EoS)? • and can it be done consistently? • modification of hadronic stage needed?? Csörgő, Akkelin, Hama, Lukács, Sinyukov PRC67 034904 (2003) Heinz & Kolb, hep-ph/0206278 2nd Warsaw Meeting on Correlations and Resonances

  32. To do… • Us • finalize analysis/systematic errors • BW fits to final 200 GeV data (spectra, v2, asHBT) – does it hang consistently together? • Theorists • can satisfactory FO be reached faster (e.g. more explosive EoS)? • more constraints in that direction! • modification of hadronic stage needed?? Csörgő, Akkelin, Hama, Lukács, Sinyukov PRC67 034904 (2003) Heinz & Kolb, hep-ph/0206278 2nd Warsaw Meeting on Correlations and Resonances

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