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arXiv · 1404.7850

Self-consistent conversion of a viscous fluid to particles

Denes Molnar·Zack Wolff
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Abstract

Comparison of hydrodynamic and "hybrid" hydrodynamics+transport calculations to heavy-ion data inevitably requires the conversion of the fluid to particles. For dissipative fluids the conversion is ambiguous without additional theory input complementing hydrodynamics. We obtain self-consistent shear viscous phase space corrections from linearized Boltzmann transport theory for a gas of hadrons. These corrections depend on the particle species, and incorporating them in Cooper-Frye freezeout affects identified particle observables. For example, with additive quark model cross sections,proton elliptic flow is larger than pion elliptic flow at moderately high $p_T$ in $Au+Au$ collisions at RHIC. This is in contrast to Cooper-Frye freezeout with the commonly used "democratic Grad" ansatz that assumes no species dependence. Various analytic and numerical results are also presented for massless and massive two-component mixtures to aid the interpretation. Self-consistent viscous corrections for each species are tabulated in Appendix F for convenient inclusion in pure hydrodynamic and hybrid calculations.

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Denes Molnar, Zack Wolff. 2017-02-14. Self-consistent conversion of a viscous fluid to particles. https://doi.org/10.1103/physrevc.95.024903

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