Anisotropic flows and the shear viscosity of the QGP within an event-by-event massive parton transport approach

Abstract

Abstract We have developed an event-by-event relativistic kinetic transport approach to study the build up of the anisotropic flows $$v_{n}(p_T)$$ vn(pT) for a system at fixed $$\eta /s(T)$$ η/s(T) . The partonic approach describe the evolution of massless partons which imply $$\epsilon =3p$$ ϵ=3p as Equation of State (EoS). We extend previous studies to finite partonic masses tuned to simulate a system that expand with an EoS close to the recent lQCD results. We study the role of EoS and the effect of $$\eta /s(T)$$ η/s(T) ratio on the build up of $$v_n(p_T)$$ vn(pT) up to $$n=5$$ n=5 for two beam energies: RHIC energies at $$\sqrt{s}=200$$ s=200 GeV and LHC energies at $$\sqrt{s}=2.76$$ s=2.76 TeV. We find that for the two beam energies considered the suppression of the $$v_n(p_T)$$ vn(pT) due to the viscosity of the medium have different contributions coming from the cross over or QGP phase. We shows that in ultra-central collisions (0–0.2%) the $$v_n(p_T)$$ vn(pT) have a stronger sensitivity to the T dependence of $$\eta /s$$ η/s that increases with the order of the harmonic n. Finally, we discuss the results for the integrated flow harmonics $$\langle v_{n} \rangle $$ ⟨vn⟩ in ultra-central collisions pointing-out how the relative strength of $$\langle v_{n} \rangle $$ ⟨vn⟩ depend on the colliding energies as well as on the freeze-out dynamics.