Flow harmonics from self-consistent particlization of a viscous fluid

Abstract

The quantitative extraction of quark-gluon plasma (QGP) properties from heavy-ion data, such as its specific shear viscosity $\eta /s$, typically requires comparison to viscous hydrodynamic or "hybrid" hydrodynamics+transport simulations. In either case, one has to convert the fluid to hadrons, yet without additional theory input the conversion is ambiguous for dissipative fluids. Here, shear viscous phase-space corrections calculated using linearized transport theory are applied in Cooper-Frye freezeout to quantify the effects on anisotropic flow coefficients $v_n(p_T)$ at both RHIC and LHC energies. Expanding upon our previous flow harmonics studies [1,2], we calculate pion and proton $v_2(p_T)$, $v_4(p_T)$, and $v_6(p_T)$. Unlike in Ref. [1], we incorporate a hadron gas that is chemically frozen below a temperature of 175 MeV, and use hypersurfaces from realistic viscous hydrodynamic simulations. With additive quark model cross sections and relative phase-space corrections with $p^{3/2}$ momentum dependence, rather than the quadratic Grad form, we find at moderately high transverse momentum noticeably higher $v_4(p_T)$ and $v_6(p_T)$ for protons than for pions. In addition, the value of $\eta /s$ deduced from elliptic flow data differs by nearly 50\% from the value extracted using the naive "democratic Grad" form of freeze-out distributions. To facilitate the use of the self-consistent viscous corrections calculated here in hydrodynamic and hybrid calculations, we also present convenient parameterizations of the corrections for the various hadron species (cf. Table I).

Added Figure 4, subsection III E, 4 References [29-32], and one footnote [34]. Also added an outline of the paper at the end of the introduction, some discussion of Eq. (1), and fixed the redundant alpha notation in Sec III D to kappa. 12 pages, 11 Figures, 1 Table

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• Triangular flow in hydrodynamics and transport theory
• Hydrodynamic Models for Heavy Ion Collisions
• Influence of the shear viscosity of the quark-gluon plasma on elliptic flow in ultrarelativistic heavy-ion collisions
• Dissipative effects from transport and viscous hydrodynamics
• Chemical freeze-out temperature in hydrodynamical description of Au+Au collisions at sqrt(s_NN) = 200 GeV
• Fluid dynamics with saturated minijet initial conditions in ultrarelativistic heavy-ion collisions
• Shear viscosity of hadrons with K-matrix cross sections
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