Eur. Phys. J. C (2007) 49: 303-308
https://doi.org/10.1140/epjc/s10052-006-0125-2

Regular Article - Theoretical Physics

Is constituent quark scaling a unique sign of parton recombination?

¹ Institut für Theoretische Physik, J.W. Goethe Universität, Max von Laue Strasse 1, 60438, Frankfurt am Main, Germany
² Frankfurt Institute for Advanced Studies (FIAS), Max von Laue Strasse 1, 60438, Frankfurt am Main, Germany
³ Physics Department, Tsinghua University, Beijing, 100084, China

^* e-mail: bleicher@th.physik.uni-frankfurt.de

Received: 1 August 2006
Published online: 2 December 2006

Abstract

We study the transverse momentum dependence of the anisotropic flow v₂ for π, K, nucleon, Λ, Ξ and Ω for Au+Au collisions at within two independent string-hadron transport approaches (RQMD and UrQMD). Although both models reach only 60% of the absolute magnitude of the measured v₂, they both predict the particle-type dependence of v₂ as observed by the RHIC experiments: v₂ exhibits a hadron-mass hierarchy in the low p_T region and a number-of-constituent-quark (NCQ) dependence in the intermediate p_T region. The failure of the hadronic models to reproduce the absolute magnitude of the observed v₂ indicates that transport calculations of heavy-ion collisions at RHIC must incorporate interactions among quarks and gluons in the early, hot and dense phase. The presence of an NCQ scaling in the string-hadron model results suggests that the particle-type dependences observed in heavy-ion collisions at intermediate p_T might be related to the hadronic cross sections in vacuum rather than to the hadronization process itself.