Equation of state and speed of sound of (2+1)-flavor QCD in strangeness-neutral matter at non-vanishing net baryon-number density

Abstract

We update results on the QCD equation of state in (2+1)-flavor QCD with non-zero conserved charge chemical potentials obtained from an eighth-order Taylor series. We present results for basic bulk thermodynamic observables of strangeness-neutral strong-interaction matter, i.e. pressure, number densities, energy and entropy density, and resum Taylor series results using Pad\'e approximants. Furthermore, we calculate the speed of sound as well as the adiabatic compression factor of strangeness-neutral matter on lines of constant entropy per net baryon number. We show that the equation of state ($P(n_B), \epsilon (n_B)$) is already well described by the $4^{\rm th}$-order Taylor series in almost the entire range of temperatures accessible with the beam energy scan in collider mode at the Relativistic Heavy Ion Collider.