Making the most of Taylor expansion and imaginary μ

We present preliminary results for the curvature of the pseudocritical line and susceptibilities in N_f = 2 + 1 flavor QCD. The computations are carried out on lattice sizes of 16³ × 4, at matching parameters of early work of the Bielefeld group. Emphasis is placed on the control of systematic errors, by cross-validating results obtained by use of the Taylor expansion and measurements at imaginary chemical potential. To this end, we generalize the magnetic equation of state to the analysis of the number density, and we extend it to imaginary values of the chemical potential.