Speaker
Description
Taylor expansion in powers of baryon chemical potential ($\mu_B$) is an oft-used method in lattice QCD to compute QCD thermodynamics for $\mu_B\ne0$. We introduce a new way of resumming the contribution of the first $N$ Taylor coefficients to the lattice QCD equation of state to all orders in $\mu_B$. The method reproduces the truncated Taylor expansion when re-expanded in powers of $\mu_B$. We apply the proposed approach to high-statistics lattice QCD calculations using 2+1 flavors of Highly Improved Staggered Quarks with physical quark masses on $32^3\times8$ lattices and for temperatures $T\approx145-175$ MeV. We demonstrate that our resummed version leads to a markedly improved convergence compared to the standard Taylor series approach. We also demonstrate the connection between our approach and reweighting. Lastly, our method runs into the Sign Problem which allows us to determine the maximum value of $\mu_B$ beyond which this method breaks down. We connect this maximum value of $\mu_B$ to the zeros of the partition function in the complex-$\mu_B$ plane.
