On the critical end point of QCD

We investigate the critical end point of QCD with two flavours of light dynamical quarks at finite lattice cutoff $a=1/4T$ using a Taylor expansion of the baryon number susceptibility. We find a strong volume dependence of its radius of convergence. In the large volume limit we obtain ${\mu }_B/T\approx 1.1$ as the radius of convergence at $T/T_c\approx 0.95$ where $T_c$ is the crossover temperature at zero chemical potential. Since this estimate is a lower bound on the critical end point of QCD, the above small value of $\mu$ may place it in the range of observability in energy scans at the Relativistic Heavy-Ion Collider (RHIC).