Mass ordering of differential elliptic flow and its violation for phi mesons

Abstract

We simulate the dynamics of Au+Au collisions at the Relativistic Heavy Ion Collider (RHIC) with a hybrid model that treats the dense early quark-gluon plasma (QGP) stage macroscopically as an ideal fluid, but models the dilute late hadron resonance gas (HG) microscopically using a hadronic cascade. By comparing with a pure hydrodynamic approach we identify effects of hadronic viscosity on the transverse momentum spectra and differential elliptic flow v_2(p_T). We investigate the dynamical origins of the observed mass-ordering of v_2(p_T) for identified hadrons, focusing on dissipative effects during the late hadronic stage. We find that, at RHIC energies, much of the finally observed mass-splitting is generated during the hadronic stage, due to build-up of additional radial flow. The phi meson, having a small interaction cross section, does not fully participate in this additional flow. As a result, it violates the mass-ordering pattern for v_2(p_T) that is observed for other hadron species. We also show that the early decoupling of the phi meson from the hadronic rescattering dynamics leads to interesting and unambiguous features in the p_T-dependence of the nuclear suppression factor R_AA and of the phi/p ratio.

14 pages, 11 figures; Figures and discussion updated

References in corpus (4)

• Viscosity in Strongly Interacting Quantum Field Theories from Black Hole Physics
• Viscosity Information from Relativistic Nuclear Collisions: How Perfect is the Fluid Observed at RHIC?
• Suppression of elliptic flow in a minimally viscous quark-gluon plasma
• Fluctuating initial conditions in heavy-ion collisions from the Glauber approach

Cited by in corpus (5)

• Fully integrated transport approach to heavy ion reactions with an intermediate hydrodynamic stage
• Multiplicity scaling in ideal and viscous hydrodynamics
• Anisotropic fluid dynamics in the early stage of relativistic heavy-ion collisions
• Parton Distributions at Hadronization from Bulk Dense Matter Produced at RHIC
• Hadronic dissipative effects on transverse dynamics at RHIC