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Charm elliptic flow at RHIC. 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. B. Zhang 1 , L.W. Chen 2 , C.M. Ko 3
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Charm elliptic flow at RHIC • 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 B. Zhang1, L.W. Chen2, C.M. Ko3 1Arkansas State University, 2Shanghai Jiao Tong University, 3Texas A&M University 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.
Charm Collective Flow • Charm quarks are formed early during an A+A collision • mc=1.35GeV,τ≈0.15fm/c • They are rare particles • dN/dy≈2 in 200GeVAuAu • Modifications of charm spectrum reveal properties of sQGP Electron pT distribution is not sensitive to charm final state interactions. It is necessary to go beyond pT distribution. Batsouli et al., PLB557,26(2003)
Charm Collective Flow At mid-rapidity, coefficient of next order in the azimuthal angle Fourier expansion is the elliptic flow parameter, v2. 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?
Wang& Gyulassy PRD43,44,45 HIJING (Heavy Ion Jet Interaction Generator) Energy in strings and minijet partons A+A Fragment excited strings into partons Zhang, CPC82 ZPC (Zhang's Parton Cascade) Parton dynamics till freezeout Coalescence into hadrons ART (A Relativistic Transport model) Hadron dynamics. Resonance decays. Li&Ko,PRC52 AMPT model with String Melting (Lin&Ko, PRC65, Lin,Ko,Pal,PRL89)
AMPT model with String Melting Chen et al.,PLB605,95(2005) Reasonable description of light hadron low pT spectra and elliptic flow Chen et al.,PRC69,031901(2004)
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 pT not sensitive to final state interactions Zhang et al.,nucl-th/0502056.
Differential elliptic flow • Quark elliptic flow has mass ordering • Light, heavy quarks saturate at same v2 • Elliptic flow sensitive to cross section • D meson e-flow reflects c quarks e-flow • Electron e-flow traces D meson e-flow
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.)
Summary and Outlook • Charm pt spectrum reflects charm final state interactions. • Electron pt spectrum is not very sensitive to charm rescatterings. • Charm elliptic flow saturates at larger pt than light quark to about the same value. • Electron elliptic flow follows charm elliptic flow.Large electron v2 indicates strong charm final state interactions with QGP.
