Reliable estimation of the radius of convergence in finite density QCD

Understand

We study different estimators of the radius of convergence of the Taylor series of the pressure in finite density QCD.

• We adopt the approach in which the radius of convergence is estimated first in a finite volume, and the infinite-volume limit is taken later.
• This requires an estimator for the radius of convergence that is reliable in a finite volume.
• Based on general arguments about the analytic structure of the partition function in a finite volume, we demonstrate that the ratio estimator cannot work in this approach, and propose three new estimators, capable of extracting reliably the radius of convergence, which coincides with the distance from the origin of the closest Lee-Yang zero.