1. Charm elliptic flow at RHIC B. Zhang 1, L.W. Chen 2, C.M. Ko 3 1 Arkansas State University, 2 Shanghai Jiao Tong University, 3 Texas A&M University Charm collective flow and properties of sQGP The AMPT model with string melting Implementation of charm particles transverse momentum spectra elliptic flow of charm particles Summary Work supported by the National Science Foundation under Grant No. 0140046 and Grant No. 0098805, by the Welch Foundation under Grant No. A-1385, and by the National Natural Science Foundation of China under Grant No. 10105008.

2. Charm Collective Flow Charm quarks are formed early during an A+A collision m c =1.35GeV, τ ≈0.15fm/c They are rare particles dN/dy≈2 in 200GeVAuAu Modifications of charm spectrum reveal properties of sQGP Batsouli et al., PLB557,26(2003) Electron p T distribution is not sensitive to charm final state interactions. It is necessary to go beyond p T distribution.

3. Charm Collective Flow Greco et al.,PLB595,202(2004) Coalescence at hadronization q elliptic flow from h, π data Assume c, q same elliptic flow D meson elliptic flow sensitive to charm final state interactions Question: How does the dynamics affect the flow? At mid-rapidity, coefficient of next order in the azimuthal angle Fourier expansion is the elliptic flow parameter, v 2.

4. AMPT model with String Melting (Lin&Ko, PRC65, Lin,Ko,Pal,PRL89) Zhang, CPC82 Fragment excited strings into partons ZPC (Zhang's Parton Cascade) Parton dynamics till freezeout Wang& Gyulassy PRD43,44, 45 HIJING (Heavy Ion Jet Interaction Generator) Energy in strings and minijet partons A+A Li&Ko,PRC52 Coalescence into hadrons Hadron dynamics. Resonance decays. ART (A Relativistic Transport model)

5. AMPT model with String Melting Chen et al.,PLB605,95(2005) Chen et al.,PRC69,031901(2004) Reasonable description of light hadron low p T spectra and elliptic flow

6. Transverse momentum distributions Momentum space power law parameterization of STAR data Coordinate space binary collision scaling σ=3mb for perturbative interactions σ=10mb for strongly interacting QGP Electron p T not sensitive to final state interactions Zhang et al.,nucl-th/0502056.

7. Differential elliptic flow Quark elliptic flow has mass ordering Light, heavy quarks saturate at same v 2 Elliptic flow sensitive to cross section D meson e-flow reflects c quarks e-flow Electron e-flow traces D meson e-flow

8. Differential elliptic flow e-flow sensitive to charm final state interactions data indicate strong charm final state interactions Large cross section indicates D meson resonances in QGP? (See also Chen and Ko,JPG31,S49(2005); Molnar,JPG31,S421(2005); Moore and Teaney,PRC,71,064904(2005); vanHees and Rapp, PRC71,034907(2005); Bratkovskaya et al.,PRC71,044901(2005); Djordjevic et al,nucl-th/0507019.)

9. Summary and Outlook  Charm p t spectrum reflects charm final state interactions.  Electron p t spectrum is not very sensitive to charm rescatterings.  Charm elliptic flow saturates at larger p t than light quark to about the same value.  Electron elliptic flow follows charm elliptic flow. Large electron v 2 indicates strong charm final state interactions with QGP.

10. Elliptic flow comparisons