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2-particle correlation at RHIC. Fabrice Reti è re, LBNL for the STAR collaboration. Hydro at RHIC Rather successful for spectra and elliptic flow But, cannot describe pion HBT A blast wave model? Very strong flow Short emission duration.
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2-particle correlation at RHIC Fabrice Retière, LBNL for the STAR collaboration
Hydro at RHIC Rather successful for spectra and elliptic flow But, cannot describe pion HBT A blast wave model? Very strong flow Short emission duration More constraints : new 2-particle correlations from STAR Pion HBT with respect to the reaction plane Kaon HBT Kaon – pion correlations Outlines
Blast wave features Interplay between flow and temperature Correlation position - momentum Short emission duration Kt = pair Pt Rside Rout Pion HBT explained in a blast wave scenario Data, Phys.Rev.Lett. 87, 082301 (2001) bt 6 5 p+ p- Rout (fm) 4 R 6 5 Model : R = 13.5 fm, t = 1.5 fm/c T = 110 MeV, <bt> = 0.52c Rside (fm) 4 Hydro lower limit 1 Rout/Rside 0.9 0.8 0.3 0.1 0.2 Pt (GeV/c)
Additional features for v2 Momentum and position anisotropy p Other blast wave model successSpectra and elliptic flow STAR preliminary - K- 1/mT dN/dmT (a.u.) Submitted to PRL Masashi Kaneta mT - m[GeV/c2] A. Poskanzer, R. Snellings, S.Voloshin
Oscillations From flow From space asymmetry HBT and Elliptic flow Rside2 (fm2) without flow Only space asymmetry f=90 degree Rout small Rside large f=0 degree Rout large Rside small In plane example f (deg)
Clear in-plane oscillation Blast wave fit R=10 fm, T=110 MeV, <bt> = 0.52c Consistent with other measurements Favor a scenario with an anisotropy both in space and momentum HBT and Elliptic flowResult from STAR STAR preliminary Randy Wells, Mike Lisa
More constraints to the blast wave model : mass dependence Blast wave (a.u.) p K p 0.6 0.5 NA44 @ SPS PRL 87 (2001) 112301 0.4 0. 0. 0.2 0.4 0.6 0.8 1. 1.2 mT (GeV/c2)
Rinv = 4.5 ± 0.3 fm (stat) Coming soon 2D/3D HBT Needed for comparison to the blast wave model Mass scaling?Kaon HBT C(Qinv) STAR preliminary Qinv (GeV) Sergei Panitkin
Static sphere : R= 7 fm ± 2 fm (syst+stat) Blast wave T = 110 MeV (fixed) <bt> = 0.52c (fixed) R = 13 fm ± 4 fm (syst+stat) Consistent with other measurements Kaon – pion correlation STAR preliminary
Probing the space-time emission asymmetry Catching up Large interaction time Large correlation Moving away Small interaction time Small correlation • Ratio • Sensitive to the space-time asymmetry Kinematics selection
Evidence of a space – time asymmetry tp-tK ~ 4fm/c ± 2 fm/c, static sphere Consistent with “default” blast wave calculation Space-time asymmetry STAR preliminary Pion <pt> = 0.12 GeV/c Kaon <pt> = 0.42 GeV/c
New measurements from STAR : Pion HBT with respect to reaction plane Kaon HBT Kaon-pion CF Qualitative agreement with a blast wave scenario But, so far, cannot be achieved by any hydro or microscopic model Next Pion HBT @ 200 GeV (and others) More statistics for reaction plane dependence Different mass 3D K+,K- , proton, K0s, L More non-identical Pion-proton Proton-L @ 200GeV Pion-X- @ 200GeV? Conclusions and outlook
Consistent with Spectra Elliptic flow Pion HBT Pion HBT wrt reaction plane Pion – kaon correlation function Question for theorists How to get there? Strong flow and short emission duration at RHIC Kaon <pt> = 0.42 GeV/c Pion <pt> = 0.12 GeV/c
Kaon Hbt 7 MeV/c bins Positive Kaons, Mult 3 (~11% Central), Pt 150-400 MeV/c, |y|<0.3 Qinv (GeV/c)
Chi2 contour Tth[GeV] Tth[GeV] s [c] s [c]
color: c2 levels from HBT data error contour from elliptic flow data