New 4D lattice QCD equation of state: Extended density coverage from a generalized T' expansion

We present a new equation of state for QCD in which the temperature T and the three chemical potentials for baryon number μB, electric charge μQ, and strangeness μS can be varied independently. This result is based on a generalization of the T' expansion scheme, thanks to which the diagonal μB extrapolation was pushed up to a baryo-chemical potential μB =T ∼ 3.5 for the first time. This considerably extended the coverage of the Taylor expansion, limited to μB =T < 2.5–3. As a consequence, we are able to offer a substantially larger coverage of the four-dimensional QCD phase diagram as well, compared to previously available Taylor expansion results. Our findings are based on new continuum estimated lattice data on the full set of second- and fourth-order fluctuations.