2008/05/31 by G. Ferini, M. Colonna, M. Di Toro +2 · 3 citations
Mathematics · Physics and Astronomy · #Coalescence (physics) #Elliptic flow #Geometry #Hadronization #High-Energy Particle Collisions Research #Mathematics #Mechanics #Nuclear physics #Particle physics theoretical and experimental studies #Physics #Quantum Chromodynamics and Particle Interactions #Quantum mechanics #Quark #Scaling #Thermodynamics #hep-ph #nucl-th
paper · pdf · doi:10.1016/j.physletb.2008.10.062
published as Phys.Lett.B670:325-329,2009 · 5 pages, 5 figures. Two points in fig.4 has been changed
arxiv created 2008/06/27 · openalex publication_date 2008/11/09 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Within a parton cascade approach we investigate the scaling of the differential elliptic flow v2(pT) with eccentricity ϵx and system size and its sensitivity to finite shear viscosity. We present calculations for shear viscosity to entropy density ratio η/s in the range from 1/4π up to 1/π, finding that the v2 saturation value varies by about a factor 2. Scaling of v2(pT)/ϵx is seen also for finite η/s which indicates that it does not prove a perfect hydrodynamical behavior, but is compatible with a plasma at finite η/s. Introducing a suitable freeze-out condition, we see a significant reduction of v2(pT) especially at intermediate pT and for more peripheral collisions. This causes a breaking of the scaling for both v2(pT) and the pT-averaged v2, while keeping the scaling of v2(pT)/〈v2〉. This is in better agreement with the experimental observations and shows as a first indication that the η/s should be significantly lower than the pQCD estimates. We finally point out the necessity to include the hadronization via coalescence for a definite evaluation of η/s from intermediate pT data.