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M. Oldenburg STAR Heavy Flavor Workshop October 13–15, 2005, LBNL 1 Multi-strange Hadron v 2 and Partonic Collectivity Markus Oldenburg Lawrence Berkeley.

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Presentation on theme: "M. Oldenburg STAR Heavy Flavor Workshop October 13–15, 2005, LBNL 1 Multi-strange Hadron v 2 and Partonic Collectivity Markus Oldenburg Lawrence Berkeley."— Presentation transcript:

1 M. Oldenburg STAR Heavy Flavor Workshop October 13–15, 2005, LBNL 1 Multi-strange Hadron v 2 and Partonic Collectivity Markus Oldenburg Lawrence Berkeley National Laboratory STAR Heavy Flavor Workshop October 1315, 2005

2 M. Oldenburg STAR Heavy Flavor Workshop October 13–15, 2005, LBNL 2 Overview Motivation on why to measure v 2 of multi-strange hadrons Analysis details and technique Data and results Discussion Conclusion Outlook: from multi-strange to heavy flavor

3 M. Oldenburg STAR Heavy Flavor Workshop October 13–15, 2005, LBNL 3 Timeline of a heavy-ion collision Time partonic stage thermal photons hadronization Ξ,, hadronic stage, K, p direct photons initial collisions hard scatterings, jet production by S. Bass

4 M. Oldenburg STAR Heavy Flavor Workshop October 13–15, 2005, LBNL 4 Flow of strange hadrons STAR: freeze-out of multi-strange hadrons - at higher temperature T fo - with lower collective velocity T small cross section of strange hadrons with non- strange hadrons sensitivity to the early, partonic stage Nucl. Phys. A715, 458c (2003) Phys. Rev. Lett. 92, (2004) Phys. Rev. Lett. 92, (2004) (GeV)

5 M. Oldenburg STAR Heavy Flavor Workshop October 13–15, 2005, LBNL 5 Importance of v 2 is a true signal from the early stage of the collision! anisotropic flow measurement of will conclude: –type of the system at an early stage partonic vs. hadronic –origin of observed scaling at intermediate p T mass vs. particle type Kaon coalescence effectively ruled out as a dominant channel for production at these energies. STAR: Phys. Rev. C65, (R) (02) Phys. Lett. B612, 181 (2005)

6 M. Oldenburg STAR Heavy Flavor Workshop October 13–15, 2005, LBNL 6 x z y pxpx pypy y x non-central collisions: azimuthal anisotropy in coordinate-space interactions asymmetry in momentum-space sensitive to early time in the systems evolution Measurement: Fourier expansion of the azimuthal p T distribution Elliptic flow v 2

7 M. Oldenburg STAR Heavy Flavor Workshop October 13–15, 2005, LBNL 7 Dataset system: Au+Au collisions energy: s NN = 200 GeV event sample: ~11 M events centrality:0–80 % event plane resolution~75 % correction:

8 M. Oldenburg STAR Heavy Flavor Workshop October 13–15, 2005, LBNL 8 Particle identification and mass spectra Ξ - and (anti- Ξ) + identified via decay topology: Ξ Λ + and Λ p + background estimated by rotating the Λ by 180° in the transverse plane > 450,000 particles identified Ω - and (anti-Ω) + identified via decay topology: Λ + K and p + background estimated by rotating the Λ by 180° in the transverse plane > 13,000 particles identified identified via decay topology: K + + K - background estimation by event mixing > 10,000,000 particles identified results by Sarah Blyth

9 M. Oldenburg STAR Heavy Flavor Workshop October 13–15, 2005, LBNL 9 New analysis technique analysis method: v 2 vs. m inv motivated by Borghini et al. [nucl-th/ ] advantages over standard method: –only one fit per p T bin smaller systematic uncertainties new method used for K 0 S, Λ, Ξ,, and analysis standard method and v 2 vs. m inv method give consistent results SIG + BG BG (SIG+BG) SIG (SIG+BG) v 2 TOT (m inv )

10 M. Oldenburg STAR Heavy Flavor Workshop October 13–15, 2005, LBNL 10 v 2 of multi-strange hadrons _ _ baryons mesons Ξ+ΞΞ+Ξ Ω+ΩΩ+Ω 200 GeV Au+Au v2v2 common fit to K and Λ n = number of constituent quarks [X. Dong et al., Phys. Lett. B597 (2004)] p T /n > 0.75 GeV/c 2 /ndf for NCQ=2 2 /ndf for NCQ=3 Ξ+ΞΞ+Ξ 82.7/627.4/6 Ω+ΩΩ+Ω 4.1/32.1/3 2.0/57.4/5 _ _ results by Sarah Blyth

11 M. Oldenburg STAR Heavy Flavor Workshop October 13–15, 2005, LBNL 11 Discussion of strange hadron v 2 results flows as strongly as other mesons. Collective flow is generated during the partonic stage already. The strange baryons Ξ and Ω show strong elliptic flow. The Ξ v 2 clearly follows the baryon v 2 (p T ). STAR preliminary Hydro: P. Huovinen, priv. comm. (2004) results by Sarah Blyth K 0 S and Λ results by Yan Lu

12 M. Oldenburg STAR Heavy Flavor Workshop October 13–15, 2005, LBNL 12 Conclusions from the measurements v 2 of multi-strange hadrons: –, Ξ, and show strong elliptic flow. – Their behavior is similar to the other mesons and baryons. = They flow as strongly as the other particles. NCQ scaling of v 2 : –observed scaling is a meson baryon, not a mass effect! Collectivity develops early among partons! = Partonic Collectivity at RHIC Thermalization ?

13 M. Oldenburg STAR Heavy Flavor Workshop October 13–15, 2005, LBNL 13 Timeline of a heavy-ion collision Time partonic stage thermal photons hadronization Ξ,, hadronic stage, K, p direct photons initial collisions hard scatterings, jet production production of heavy quarks by S. Bass

14 M. Oldenburg STAR Heavy Flavor Workshop October 13–15, 2005, LBNL 14 Heavy-Flavor Quarks Mass (MeV/c 2 ) B. Mueller, nucl-th/ Even in a QGP with chiral restoration, the c, b (and t) quarks stay heavy. If charm quarks show collective behavior (= flow) the must have suffered frequent interactions with the light quarks u, d, s. The light quarks u, d, s must be thermalized.


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