The BlastWave parameterization of the Some aspects of Freeze-out configuration at RHIC
Download ReportTranscript The BlastWave parameterization of the Some aspects of Freeze-out configuration at RHIC
The BlastWave of the Someparameterization aspects of Freeze-out configuration at RHIC Particle Correlations and Collective Effects at RHIC in the soft sector from some of the data NOT an overview talk by Mike Lisa Ohio State University 22 May 2003 malisa - CIPANP2003 - NYC 1 The BlastWave parameterization of the Freeze-out configuration at RHIC • First motivation – pT spectra • Application to HBT radii • Out-of-the-box application to correlations of non-identical particles • Generalization to non-central collisions • v2(pT,m) • Azimuthally-sensitive HBT • Conclusions 22 May 2003 malisa - CIPANP2003 - NYC 2 Hydro @ RHIC: trouble in x-space, good in p-space 22 May 2003 malisa - CIPANP2003 - NYC Heinz & Kolb, hep-ph/0204061 3 Hydrodynamics & (soft sector) pT spectra at RHIC • (Boost-invariant) hydro: good reproduction of (,K,p) pT spectra near midrapidity • Spectra do not scale with pT (or mT) • shape depends on mass: superposition of thermal motion on collective flow velocity field • Transverse fluid rapidity yT (aka ) ~ linear in r • Schnedermann et al (’93): 2-parameter (T, max) “hydro-inspired” functional form to fit spectra. • Useful to extract thermal, collective energy R dN p sinh m sinh 0 r dr mT I0 T K1 T mT dmT T T 1, 2 r max R tanh -1 “Box” unrealistic? Reasonable to consider third Teaney, Lauret & Shuryak, nucl-th/0110037 parameter: “skin thickness” (more later) Note hard-edge (“box profile”) approximation 22 May 2003 malisa - CIPANP2003 - NYC Heinz & Kolb, hep-ph/0204061 4 T, 0 from published (130 GeV) pT spectra Central Midcentral Peripheral T (MeV) 108 3 106 2 95 4 0 0.88 0.01 0.87 0.02 0.81 0.02 • reasonable dependence on centrality • ~consistent with other BlastWaves Tth = 107 MeV = 0.55 22 May 2003 M. Kaneta malisa - CIPANP2003 - NYC 5 • pT spectra are insensitive to spatial scale R • However, two-particle correlations probe R → “new” parameter (not really) y (fm) Spatial implications – central collisions 10 =0.4 0 -10 -10 y (fm) • Also: gradients in collective velocity + finite geometric scale → space-momentum correlations • Homogeneity scale decreases with pT • Spatial separation between different-mass particles 0 x (fm)10 10 =0.8 pions 0 kaons protons -10 -10 0 x (fm)10 R=10 fm, T=0.1 GeV, 0=0.9 22 May 2003 malisa - CIPANP2003 - NYC 6 Timescale considerations • SSH: Freeze-out at constant proper time 0 dN ( 0 ) d • pT spectra insensitive to 0 → another “hidden” parameter to explore with 2-particle correlations (e.g. RL) 00 • Finally, 2-particle correlations sensitive to emission duration , as well as evolution duration 0 → generalize SSH model ( 0 ) 2 dN exp 2 d 2 • pT spectra insensitive to 22 May 2003 malisa - CIPANP2003 - NYC 7 Fits to published (130 GeV) pion HBT Central Midcentral Peripheral T (MeV) 108 3 106 2 95 4 0 0.88 0.01 0.87 0.02 0.81 0.02 “R” (fm) 13 11 9 0 (fm/c) 8.9 0.3 7.4 1.2 6.5 0.8 (fm/c) 0.0 1.4 0.8 3.2 0.8 1.9 central midcentral peripheral • ~consistent with STAR • PHENIX transverse fall faster than BW • Imperfect fit suggests short evolution and (especially) emission timescales • Evolution of source size, evolution time with centrality reasonable 22 May 2003 malisa - CIPANP2003 - NYC 8 Detour: Recent analysis developments • RHIC analyses used “standard” Coulomb correction, used by previous experiments • “apples-to-apples” extension of systematics A (q ) N (1 exp(R ij2qiq j )) B(q) K coul (q) f 177c (2002) STAR, QM01; NPA698, • Effects of “diluting” CC (resonances, etc) explored & reported @ QM01 • Ro affected most K coul (q) 1 f (K coul (q) 1) 0 f 1 • Y2 data: dilution effect vs pT, centrality • RO/RS ~ 10-15% increase when f = ≈ 0.5 • More correct CC method of Bowler (’91) & Sinyukov (’98), used by CERES (’02) • Similar effect on radii as dilution with f = A (q ) N 1 K coul (q) 1 exp(R ij2qiq j 1 B(q) 22 May 2003 No Coulomb CC “Standard” Coulomb CC In “right” direction, but does not solve • RO/RS problem • RL problem BW: ~2 fm/c / finite aS or… broken! malisa - CIPANP2003 - NYC 9 A check from another angle: Kaon-pion correlations: dominated by Coulomb STAR preliminary; F. Retiere, QM02; central Au130Au BlastWave Smaller source stronger (anti)correlation K- correlation ~well-described by BW with same parameters as spectra, HBT But with non-identical particles, we can access more information… 22 May 2003 malisa - CIPANP2003 - NYC 10 Initial idea: probing emission-time ordering purple K emitted first green is faster • Catching up: cosY 0 • • • Moving away: cosY 0 purple K emitted first green is slower • • Crucial point: kaon begins farther in “out” direction (in this case due to time-ordering) 22 May 2003 long interaction time strong correlation short interaction time weak correlation • Ratio of both scenarios allow quantitative study of the emission asymmetry malisa - CIPANP2003 - NYC 11 • pT spectra are insensitive to spatial scale R • However, two-particle correlations probe R → “new” parameter (not really) y (fm) Spatial implications – central collisions 10 =0.4 0 -10 -10 y (fm) • Also: gradients in collective velocity + finite geometric scale → space-momentum correlations • Homogeneity scale decreases with pT • Spatial separation between different-mass particles 0 x (fm)10 10 =0.8 pions 0 kaons protons -10 -10 Unavoidable hierarchy of emission zones 22 May 2003 0 x (fm)10 R=10 fm, T=0.1 GeV, 0=0.9 malisa - CIPANP2003 - NYC 12 Comparison (no fit) to preliminary K- STAR preliminary; F. Retiere, QM02; central Au130Au • overall scale reproduced (CF) • direction of shift reproduced (kaons emitted further out) • magnitude of effect overpredicted • data: r* = 5.6 fm • BW: r* = 6.9 fm 22 May 2003 malisa - CIPANP2003 - NYC 13 Summary for soft central data • Hydro-inspired functional form “designed” for spectra fits: T, 0 • Application to x-space probes ( HBT, K- correlations) – scales of “non-parameters” R, 0 become meaningful/measurable – “addition” (generalization) of emission timescale • Direct implications for x-space probes: – shrinking emission region with increasing pT – shifted emission regions for non-identical particles confirmed semi-quantitatively On to non-central collisions… 22 May 2003 malisa - CIPANP2003 - NYC 14 Noncentral collisions • intrinsic anisotropy in entrance channel preferential in-plane expansion (elliptic flow) • hydro reproduces v2(pT,m) (details!) @ RHIC for pT < ~1.5 GeV/c Heinz & Kolb hep-ph/0111075 22 May 2003 malisa - CIPANP2003 - NYC 15 • intrinsic anisotropy in entrance channel preferential in-plane expansion (elliptic flow) • elliptic flow quickly “self-quenches” as geometry in-plane-extended in-plane flow • hydro reproduces v2(pT,m) (details!) @ RHIC for pT < ~1.5 GeV/c in-plane geometry Noncentral collisions Heinz & Kolb, hep-th/0204061 22 May 2003 malisa - CIPANP2003 - NYC 16 Noncentral collisions later hadronic stage? • intrinsic anisotropy in entrance channel preferential in-plane expansion (elliptic flow) • hydro reproduces v2(pT,m) (details!) @ RHIC for pT < ~1.5 GeV/c • elliptic flow quickly “self-quenches” as geometry in-plane-extended • Effect of (presumed) hadronic stage? • little effect on v2 (@ RHIC) 22 May 2003 Teaney, -Lauret, malisa - CIPANP2003 NYC & Shuryak, nucl-th/0110037 17 Noncentral collisions • intrinsic anisotropy in entrance channel preferential in-plane expansion (elliptic flow) • hydro reproduces v2(pT,m) (details!) @ RHIC for pT < ~1.5 GeV/c later hadronic stage? hydro only hydro+hadronic rescatt • elliptic flow quickly “self-quenches” as geometry in-plane-extended • Effect of (presumed) hadronic stage? • little effect on v2 (@ RHIC) • RO/RS, RL increase 22 May 2003 STAR PHENIX Soff, Bass, Dumitru, PRL 2001 malisa - CIPANP2003calculation: - NYC 18 Noncentral collisions • intrinsic anisotropy in entrance channel preferential in-plane expansion (elliptic flow) later hadronic stage? in-planeextended • hydro reproduces v2(pT,m) (details!) @ RHIC for pT < ~1.5 GeV/c • elliptic flow quickly “self-quenches” as geometry in-plane-extended • Effect of (presumed) hadronic stage? • little effect on v2 (@ RHIC) • RO/RS, RL increase • freezeout geometry becomes in-plane-extended out-of-plane-extended Teaney, Lauret, & Shuryak, nucl-th/0110037 22 May 2003 malisa - CIPANP2003 - NYC 19 Noncentral collisions later hadronic stage? • intrinsic anisotropy in entrance channel preferential in-plane expansion (elliptic flow) • hydro reproduces v2(pT,m) (details!) @ RHIC for pT < ~1.5 GeV/c • elliptic flow quickly “self-quenches” as geometry in-plane-extended • Effect of (presumed) hadronic stage? • little effect on v2 (@ RHIC) • RO/RS, RL increase • freezeout geometry becomes in-plane-extended timescale effects (indep in BW) 22 May 2003 Teaney, Lauret, & Shuryak, nucl-th/0110037 malisa - CIPANP2003 - NYC 20 central midcentral peripheral Anisotropy in BW p Ry RX Central Midcentral Peripheral T (MeV) 108 3 106 2 95 4 0 0.88 0.01 0.87 0.02 0.81 0.02 a 0.06 0.01 0.05 0.01 0.04 0.01 RX (fm) 12.9 0.3 10.2 0.5 8.0 0.4 RY (fm) 12.8 0.3 11.8 0.6 10.1 0.4 0 (fm/c) 8.9 0.3 7.4 1.2 6.5 0.8 (fm/c) 0.0 1.4 0.8 3.2 0.8 1.9 2 / ndf 80.5 / 101 153.7 / 92 22 May 2003 74.3 / 68 • 0 → 0 + a ·cos(2S) – in-plane cells boost more • R → RX, RY – more cells boosting in-plane • Global fit to published Y1 – pT spectra – HBT radii – v2(pT,m) • Main “surprise”: short timescales – supported by out-of-plane freezeout geometry malisa - CIPANP2003 - NYC 21 v2 An alternative scenario – who needs flow? • saturation model – v2 : correlation b/t minijet products – no relationship to (true) reaction plane! pT (GeV/c) v2 • Can this be checked? Y. Kotchegov, K. Tuchin hep-ph0203213, nucl-th0207037 nch / nmax 22 May 2003 malisa - CIPANP2003 - NYC 22 First indirect indications of x-space anisotropy @ RHIC STAR, PRL 87 182301 (2001) Rside small Rside large check directly with azimuthally-sensitive HBT Rs2 [no-flow expectation] 22 May 2003 malisa - CIPANP2003 - NYC p 23 asHBT versus BlastWave • Minbias asHBT well-reproduced with same BlastWave from minbias v2(pT,m) • Ry = 11.4 fm s2 = 0.045 • Rx = 10.8 fm • 0 = 8.3 fm/c • = 0 ( → ~1.5 fm/c w/ Bowler CC)) • Consistent picture – convincing argument for bulk flow scenario • Saturation ???? Au+Au 130 GeV minbias • asHBT: geometry dominates dynamics • Source out-of-plane extended BAIL 22 May 2003 malisa - CIPANP2003 - NYC 24 Further systematics in Au+Au 200 GeV Centrality cuts kT-integrated 12 bins kT cuts Mid-central 4 bins • Oscillation phases: out-of-plane extended source • Source size increases, oscillations decrease with increasing centrality • 0th and 2nd harmonics only • Average size (0th harmonic) falls with kT • Mild evolution of 2nd harmonic with kT 22 May 2003 malisa - CIPANP2003 - NYC 25 “Grand summary” of asHBT Fourier Coefficients n=0 n=2 • Centrality- and kT- dependence of the -dependence summarized concisely by Fourier coefficients 2 R pT , cosn R ,n pT 2 R p , sin n T 2 o, s, l os central midcentral peripheral 22 May 2003 malisa - CIPANP2003 - NYC 26 “Grand summary” Fourier Coefficients n=0 n=2 • Centrality- and kT- dependence of the -dependence summarized concisely by Fourier coefficients 2 R pT , cosn R ,n pT 2 R p , sin n T 2 o, s, l os • Hydro predictions (*): b = 6 fm “RHIC” source “LHC” (IPES) source central midcentral peripheral • Scale of homogeneity lengths off • Phase/magnitude of oscillations from “RHIC” source in the ballpark • significance ? Heinz 22(*) May 2003& Kolb, hep-ph/0204061 malisa - CIPANP2003 - NYC 27 Evolution of spatial anisotropy • BW fit to preliminary STAR asHBT @ 200 Gev • Out-of-plane-extended freezeout geometry for all centralities RY RX – init from Glauber – final from asHBT – further constraint on evolution timescale (and dynamic models!!) 22 May 2003 malisa - CIPANP2003 - NYC 28 Summary • Flow scenario gives a consistent picture of low-pT dynamics at RHIC • BlastWave – – toy “model” designed to capture essential elements of scenario – parameters ~constrained by global fit to • spectra • HBT • v2(pT,m) – checks: • asHBT – “proof” that v2 is geometrically driven • K-pi – “proof” of x-p correlations from radial flow 22 May 2003 malisa - CIPANP2003 - NYC 29 BW - A rough picture “Reality” BlastWave version With some assumptions/prior knowledge, can identify gross properties • relative scale of child/animal • orientation/posture of child • etc. But NOT details: e.g. child’s expression, texture on pajamas More importantly: cannot tell how/why the child got there – picture can only provide feedback to true explanation (model) 22 May 2003 malisa - CIPANP2003 - NYC 30 Is BW “the” answer • • I’m convinced that it contains the major driving elements of the truth– i.e. it is approximately right – Hydro gives similar functional form – It gets trends in data qualitatively and approximately quantitatively, even for new observables for which it was not “designed” But I’m not yet totally decided how much of a “precision tool” it is. – Can we learn something physical from small discrepancies from BW? (e.g. different flow, temp for strange particles) or is that just a matter of tuning (e.g. as) and a limitation, period. • • Get a picture of me, and show it also in low resolution, and also distorted. That’s how I think of the BW representation of reality. Good only for broad strokes. Also: BW only describes the freezeout configuration (how big, how hot, how much flow, how long it took to get there, how long freezeout lasted) – it does NOT describe the evolution, so is not really a physical “model” 22 May 2003 malisa - CIPANP2003 - NYC 31 Discrepancies w/ BW Show Zhangbu/Nu’s plot of slope versus mass – strange particles different But then show effect of as on spectra – could “explain” it (needs to be investigated) Conclusion: who knows? Maybe strange particles ARE different. Still not sure if BW Is really such a “precision tool” to say something like that 22 May 2003 malisa - CIPANP2003 - NYC 32 Linked-to slides follow 22 May 2003 malisa - CIPANP2003 - NYC 33 • pT spectra are insensitive to spatial scale R • However, two-particle correlations probe R → “new” parameter (not really) y (fm) Spatial implications – central collisions as=0.3 10 =0.4 0 -10 -10 y (fm) • Also: gradients in collective velocity + finite geometric scale → space-momentum correlations • Homogeneity scale decreases with pT • Spatial separation between different-mass particles 0 x (fm)10 10 =0.8 pions 0 kaons protons -10 -10 Unavoidable hierarchy of emission zones 22 May 2003 0 x (fm)10 R=10 fm, T=0.1 GeV, 0=0.9 malisa - CIPANP2003 - NYC 34 S( x, K) mT cosh( Y) e (r,S ) e 0 / 2 2 Ku / T Jacobian 22 May 2003 Boltzman factor 2 Spatial density malisa - CIPANP2003 - NYC propertime distribution 35 Possible to “see” via HBT relative to reaction plane? p=90° • for out-of-plane-extended source, expect • large Rside at 0 2nd-order • small Rside at 90 oscillation Rside (small) Rside (large) p=0° Rs2 [no flow expectation] p 22 May 2003 malisa - CIPANP2003 - NYC 36 Indirect indications of x-space anisotropy @ RHIC STAR, PRL 87 182301 (2001) • v2(pT,m) globally well-fit by hydro-inspired “blast-wave” T (MeV) 0(c) a (c) S2 22 May 2003 dashed solid 135 20 0.52 0.02 0.09 0.02 0.0 100 24 0.54 0.03 0.04 0.01 0.04 0.01 temperature, radial flow consistent with fits to spectra anisotropy of flow boost spatial anisotropy (out-of-plane extended) malisa - CIPANP2003 - NYC 37 A shot at 200 GeV data 22 May 2003 malisa - CIPANP2003 - NYC 38 Points: preliminary STAR data Plain line: Blast wave calculation Dash line: BW without time Shifts and BW -K • Blast wave in the right ballpark • Need to decrease the uncertainties -p – In progress • Need to increase the acceptance – Need new 22 May 2003 K-p malisa - CIPANP2003 - NYC 39 Star preliminary Star preliminary Star preliminary 22 May 2003 malisa - CIPANP2003 - NYC 40 Star preliminary Star preliminary Star preliminary 22 May 2003 malisa - CIPANP2003 - NYC 41 Central (0-5%) Peripheral (30-70%) Temperature (MeV) 91.6 0.4 92.2 0.5 Maximum flow rapidity 0.993 0.001 0.870 0.002 Flow rapidity modulation 0.0161 0.0008 0.038 0.001 In-plane radius (fm) 13.86 0.07 8.67 0.09 Out-of-plane radius (fm) 14.25 0.07 10.5 0.1 Proper time (fm/c) 10.34 0.08 7.4 0.1 Emission duration (fm/c) 1.89 0.09 1.5 0.1 Chi2 / dof 2594 / 59 2070 / 59 22 May 2003 malisa - CIPANP2003 - NYC 42 here’s what’s next: • for non-central collisions, we already know (hydro – show kolb density contours) that there is anisotropy in flow field, and in geometric shape – – – one drives the other– entrance-channel anisotropy leads to flow gradient anisotropies, which means more flow in-plane (elliptic flow) hydro does good job also on THIS p-space observable (v2) [kolb vs STAR v2] hydro is not full story– what about later hadronic stage? • • • • • • – • This will mean that blastWave gets generalized – 2 more parameters show PID v2 fit of me/Fabrice (centrality cut) – good – • little effect on v2 [Teaney plot] but (reminder) significant effect on HBT radii [bass plot] (*and it’s even worse for Rlong) probably due to timescale [Teaney plot] to get a handle on that, look at (final) geometric anisotropy – it doesn’t saturate as quickly as does momentumspace anisotropy, so can play the role of a “clock” [kolb plot] both kolb and teaney hydro say out-of-plane at RHIC, but if hadronic stage included, then should be inplane. [teaney plot] let’s see – use blastwave to probe flow and shape anisotropy!!! variation with centrality makes sense etc. show STAR minbias PID fit published (don’t go into details of parameters) – check with asHBT! Randy • 22 May 2003 same parameters– good reproduction of data malisa - CIPANP2003 - NYC 43