RHIC FLOW & HBT 29 oct 2003malisa - DNP03 - Tucson, AZ1 Flow & Correlations in the soft RHIC (Selected highlights) Mike Lisa Ohio State University

RHIC FLOW & HBT 29 oct 2003malisa - DNP03 - Tucson, AZ2 Relevance of soft physics during high-pT heyday p p ? pedestal and flow subtracted Au+Au recent high-p T results: clearly a very interesting medium of dense color fields created in RHIC jet energy loss in medium (QGP?)

RHIC FLOW & HBT 29 oct 2003malisa - DNP03 - Tucson, AZ3 Relevance of soft physics during high-pT heyday ? Au+Au recent high-p T results: clearly a very interesting medium of dense color fields created in RHIC jet energy loss in medium (QGP?) (rare) high-p T particles are the probes evidence in direction of QGP existence medium itself decays largely into soft sector non-perturbative, low-Q phenomenon to understand/study this new system, must focus on soft sector dynamics/chemistry (latter discussed previously) systematic, detailed studies important here 99.5%

RHIC FLOW & HBT 29 oct 2003malisa - DNP03 - Tucson, AZ4 Bulk system dynamics at RHIC Detailed probes of dynamics through momentum- and coordinate-space characterization of the source Central collisions / azimuthally-integrated studies –p-space: spectra collective radial flow (?) –x-space: two-particle (K- ,  -  ) correlations collective radial flow (!) [impt to verify] timescales Noncentral collisions / shape analyses –p-space: elliptic flow (and beyond!) sensitivity to early stage? –x-space: azimuthally-sensitive  HBT detailed handle on anisotropic dynamics further constraints on timescales Summary emergence of a consistent picture?

RHIC FLOW & HBT 29 oct 2003malisa - DNP03 - Tucson, AZ5 K. Schweda M. Kaneta (old figure) p-space probe of bulk dynamics:  -integrated spectral shape analysis suggestive of strong collective radial flow important evidence for expanding bulk system T falls,  rises with system size

RHIC FLOW & HBT 29 oct 2003malisa - DNP03 - Tucson, AZ6 p-space probe of bulk dynamics:  -integrated spectral shape analysis suggestive of strong collective radial flow important evidence for expanding bulk system T falls,  rises with system size consistent with hydro/rescattering scenario But is it really bulk flow? test from space-time side Heinz & Kolb, hep-ph/

RHIC FLOW & HBT 29 oct 2003malisa - DNP03 - Tucson, AZ7  -integrated x-space probe: K-  correlations Coulomb FSI  like (unlike) sign charged particles show (anti-)correlation at small v rel sensitive to effective source sizes (homogeneity regions) observed at RHIC 130 GeV) consistent w/flowing source model (BW) &  HBT Pion slowerPion faster bulk collective flow  x-p correlations spatial shift between  r out  [K] and  r out  [  ] odd terms in  rel   r out  is measurable by selecting on sign of v rel shift ~consistent w/flowing source model (same parameters as for spectra, HBT)   r out  [  ]  r out  [K]  r out  STAR, nucl-ex/ DataBlastwave  r * out  (fm)-5.6±

RHIC FLOW & HBT 29 oct 2003malisa - DNP03 - Tucson, AZ8  -integrated x-space probe:  HBT bulk collective flow  x-p correlations spatial scale of homogeneity regions (measured by HBT) decreases with p T observed at RHIC roughly consistent w/ flow models w/ same flow as spectra low p T  ’s high p T  ’s Data: STAR, PRL (’01) PHENIX, PRL (’02) Fit: Retière & Lisa, in prep. Buda-Lund hydro: Csörgő et al consistent, simultaneous description of spectra, HBT, K-  BUT: imply very short timescales!

RHIC FLOW & HBT 29 oct 2003malisa - DNP03 - Tucson, AZ9 Data: STAR, PRL (’01) PHENIX, PRL (’02) Buda-Lund hydro: Csörgő et al time dN/dt Blast-wave type fits  0 ~6-9 fm/c  ~0-2 fm/c

RHIC FLOW & HBT 29 oct 2003malisa - DNP03 - Tucson, AZ10 time dN/dt Blast-wave type fits  0 ~6-9 fm/c  ~0-2 fm/c Heinz & Kolb, hep-ph/ ideal, boost-invariant hydro hydro-inspired “toy” models simultaneous description of p- and x-space strong collective flow needed “real” model: ideal boost-invariant hydro good job at p-space observables fails at x-space observables timescale issues?

RHIC FLOW & HBT 29 oct 2003malisa - DNP03 - Tucson, AZ11 Alleviations of HBT “puzzles”? Experimental: improved treatment of Coulomb interaction : Bowler (’91) & Sinyukov (’98) urged by CERES (’02) –in right direction for R O /R S but not sufficient to match hydro expectation –no effect on R L problem STAR 200 GeV central - preliminary

RHIC FLOW & HBT 29 oct 2003malisa - DNP03 - Tucson, AZ12 Alleviations of HBT “puzzles”? Experimental: improved treatment of Coulomb interaction: Bowler (’91) & Sinyukov (’98) urged by CERES (’02) –in right direction for R O /R S but not sufficient to match hydro expectation –no effect on R L problem Theoretical: modify ideal B.I. hydro –discard Boost-invariance assumption? Hirano et al RSRS RORO RLRL R O /R S Hirano & Tsuda, PRC (02) * implicit in most BlastWave parameterizations

RHIC FLOW & HBT 29 oct 2003malisa - DNP03 - Tucson, AZ13 Alleviations of HBT “puzzles”? Experimental: improved treatment of Coulomb interaction: Bowler (’91) & Sinyukov (’98) urged by CERES (’02) –in right direction for R O /R S but not sufficient to match hydro expectation –no effect on R L problem Theoretical: modify ideal B.I. hydro –discard Boost-invariance assumption? Hirano et al –discard zero-viscosity assumption? Teaney also: Lin, Molnar, Humanic et al Teaney, nucl-th/ * implicit in most BlastWave parameterizations

RHIC FLOW & HBT 29 oct 2003malisa - DNP03 - Tucson, AZ14 Alleviations of HBT “puzzles”? Teaney, nucl-th/ * implicit in most BlastWave parameterizations v2v2 Experimental: improved treatment of Coulomb interaction: Bowler (’91) & Sinyukov (’98) urged by CERES (’02) –in right direction for R O /R S but not sufficient to match hydro expectation –no effect on R L problem Theoretical: modify ideal B.I. hydro –discard Boost-invariance assumption? Hirano et al –discard zero-viscosity assumption? Teaney also: Lin, Molnar, Humanic et al –common issue: ability to simultaneously describe p-space observables also?

RHIC FLOW & HBT 29 oct 2003malisa - DNP03 - Tucson, AZ15 Further info – noncentral collisions/shape analyses “broken symmetry” for b  0 → more detailed, important physics information momentum space: increased sensitivity to early stage, EoS coordinate space: another handle on dynamical timescales P. Kolb and U. Heinz, hep-ph/ P. Kolb, nucl-th/ “radial flow” “elliptic flow”

RHIC FLOW & HBT 29 oct 2003malisa - DNP03 - Tucson, AZ16 P-space shape: Flow (radial, directed, elliptic,...) x y Radial flow: Only type of transverse flow in central collision (b=0) Integrates pressure history over complete expansion phase Elliptic flow: caused by anisotropic initial overlap region (b > 0). More weight towards early stage of expansion. Directed flow: probe earliest collision stage (pre-equilibrium, b > 0) x y z x v1v1 v2v2 v n>2 finer detail..?

RHIC FLOW & HBT 29 oct 2003malisa - DNP03 - Tucson, AZ17 Directed flow at RHIC z x geometric anisotropy in x-z plane (reaction plane)  p-space anisotropy early stage rescattering

RHIC FLOW & HBT 29 oct 2003malisa - DNP03 - Tucson, AZ18 Directed flow at RHIC geometric anisotropy in x-z plane (reaction plane)  p-space anisotropy early stage rescattering 1 st observation of directed flow at RHIC small signal, only away from y cm 3-particle cumulants, using strong v 2 [see A. Tang’s talk] no obvious “wiggle” (big uncert.) comp w/SPS: limiting fragmentation concept extends to p anisotropy? confirms in-plane elliptic RHIC non-BI models needed STAR, submitted to PRL

RHIC FLOW & HBT 29 oct 2003malisa - DNP03 - Tucson, AZ19 Preliminary v Final v Elliptic flow (v 2 ) tremendous amount of RHIC – , p T, m, centrality sensitive to EoS/QGP does B.I. approximation break down quickly? PHOBOS: Phys. Rev. Lett. 89, (2002)

RHIC FLOW & HBT 29 oct 2003malisa - DNP03 - Tucson, AZ20 Elliptic flow (v 2 RHIC tremendous amount of RHIC – , p T, m, centrality sensitive to EoS/QGP does B.I. approximation break down quickly? pT, m systematics for wide range of particles reasonably described at low-pt with common set of parameters –x-space anisotropy indicated v 2 is BIG! (~2x more particles in-plane than p T >1 GeV) R. Snelling, minbias compilation & BW STAR & PHENIX (squares)

RHIC FLOW & HBT 29 oct 2003malisa - DNP03 - Tucson, AZ21 Higher order flow coefficients? P. Kolb: “v 4 - a small, but sensitive observable for heavy ion collisions” PRC 68, (R) Strong potential to constrain model calculations and carries valuable information on the dynamical evolution of the system Magnitude, and even the sign, sensitive to initial conditions of hydro

RHIC FLOW & HBT 29 oct 2003malisa - DNP03 - Tucson, AZ22 Higher order flow coefficients! STAR, submitted to PRL cumulant analysis  v 4, v 6 !!!

RHIC FLOW & HBT 29 oct 2003malisa - DNP03 - Tucson, AZ23 Freeze-out anisotropy as an evolution “clock” anisotropic pressure gradients → preferential in-plane flow (v 2 ) → 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? hydro evolutionlater hadronic stage? P. Kolb and U. Heinz, hep-ph/ Teaney, Lauret, Shuryak, nucl-th/ STAR PHENIX hydro only hydro+hadronic rescatt Soff, Bass, Dumitru, PRL 2001 Teaney et al, nucl-th in-plane- extended out-of-plane-extended Teaney et al, nucl-th  p =0°  p =90° R S small R S big R.P.

RHIC FLOW & HBT 29 oct 2003malisa - DNP03 - Tucson, AZ24 asHBT at 200 GeV in STAR – R(  ) vs centrality 12 (!)  -bins b/t  (k T -integrated) clear oscillations observed in transverse radii centrality dependence reasonable oscillation amps higher than 2 nd -order ~ 0 → extract 0 th, 2 nd Fourier coefficients vs k T with 4  -bin analysis

RHIC FLOW & HBT 29 oct 2003malisa - DNP03 - Tucson, AZ25 asHBT at 200 GeV in STAR – R(  ) vs k T Clear oscillations observed at all k T extract 7 radius Fourier Coefficients (shown by lines) midcentral collisions (20-30%)

RHIC FLOW & HBT 29 oct 2003malisa - DNP03 - Tucson, AZ26 Estimate of initial vs F.O. source shape estimate  INIT from Glauber from asHBT:  FO =  INIT  FO <  INIT → dynamic expansion  FO > 1 → source always OOP-extended constraint on evolution time

RHIC FLOW & HBT 29 oct 2003malisa - DNP03 - Tucson, AZ27 A simple estimate –  0 from  init and  final “radial flow” P. Kolb, nucl-th/ BW →  X,  F.O. (  X >  Y ) hydro: flow velocity grows ~ t From R L (m T ):  0 ~ 9 fm/c consistent picture Longer or shorter evolution times X inconsistent toy estimate:  0 ~  0 (BW)~ 9 fm/c...but need a real model comparison → asHBT valuable “evolutionary clock” constraint for models

RHIC FLOW & HBT 29 oct 2003malisa - DNP03 - Tucson, AZ28 Broad strokes of the highlights impressive degree of detail in characterization of soft dynamics at RHIC – , pT, m, centrality,  –p-space: “v0” through v6 !!! –x-space: transverse shape analysis !!! from p- and x-space sectors, clear, consistent evidence of bulk flow can be described in simple (simplistic?) BlastWave scenario with short timescales very strong constraints on “real” dynamical models –new constraints on both early (init conditions) and late (FO) configurations plenty more work to do before we claim to understand bulk dynamics at RHIC