Saturation of elliptic flow and the transport opacity of the gluon plasma at RHIC

✍ Scribed by Dénes Molnár; Miklos Gyulassy

• Publisher: Elsevier Science
• Year: 2002
• Tongue: English
• Weight: 392 KB
• Volume: 697
• Category: Article
• ISSN: 0375-9474
• DOI: 10.1016/s0375-9474(01)01224-6

✦ Synopsis

Differential elliptic flow and particle spectra are calculated taking into account the finite transport opacity of the gluon plasma produced in Au + Au at E cm ∼ 130 A GeV at RHIC. Covariant numerical solutions of the ultrarelativistic Boltzmann equation are obtained using the MPC parton cascade technique. For typical pQCD (∼ 3 mb) elastic cross sections, extreme initial gluon densities, dN g /dη ∼ 15 000, are required to reproduce the elliptic flow saturation pattern reported by STAR. However, we show that the solutions depend mainly on the transport opacity, χ = dz σ t ρ g , and thus the data can also be reproduced with dN g /dη ∼ 1000, but with extreme elastic parton cross sections, ∼ 45 mb. We demonstrate that the spectra and elliptic flow are dominated by numerical artifacts unless parton subdivisions ∼ 100-1000 are applied to retain Lorentz covariance for RHIC initial conditions.