Bayesian Inference of the Specific Shear and Bulk Viscosities of the Quark-Gluon Plasma at Crossover from $ϕ$ and $Ω$ Observables

Abstract

Due to their weak final state interactions, the $ϕ$ meson and $Ω$ baryon provide unique probes of the properties of the quark-gluon plasma (QGP) formed in relativistic heavy-ion collisions. Using the quark recombination model with the quark phase-space information parameterized in a viscous blastwave, we study the transverse-momentum spectra and elliptic flows of $ϕ$ and $Ω$ in Au+Au collisions at $\sqrt{s_{\rm NN}} = 200$ GeV and Pb+Pb collisions at $\sqrt{s_{\rm NN}} = 2.76$ TeV. The viscous blastwave includes non-equilibrium deformations of thermal distributions due to shear and bulk stresses and thus carries information on the specific shear viscosity $η/s$ and the specific bulk viscosity $ζ/s$ of the QGP. We perform a model-to-data comparison with Bayesian inference and simultaneously obtain $η/s=(2.08^{+1.10}_{-1.09})/4π$ and $ζ/s= 0.06^{+0.04}_{-0.04}$ at $90\%$ C.L. for the baryon-free QGP at crossover temperature of about $160$ MeV. Our work provides a novel approach to simultaneously determine the $η/s$ and $ζ/s$ of the QGP at hadronization.

7 pages, 3 figures, 1 table. Presentation improved and discussions added. Accepted version to appear in PRC