Lattice-based QCD equation of state at finite baryon density: Cluster Expansion Model

The QCD equation of state at finite baryon density is studied in the framework of a Cluster Expansion Model (CEM), which is based on the fugacity expansion of the net baryon density. The CEM uses the two leading Fourier coefficients, obtained from lattice simulations at imaginary ${\mu }_B$, as the only model input and permits a closed analytic form. Excellent description of the available lattice data at both ${\mu }_B=0$ and at imaginary ${\mu }_B$ is obtained. We also demonstrate how the Fourier coefficients can be reconstructed from baryon number susceptibilities.