The critical line from imaginary to real baryonic chemical potentials in two-color QCD

The method of analytic continuation from imaginary to real chemical potentials \mu is one of the few available techniques to study QCD at finite temperature and baryon density. One of its most appealing applications is the determination of the critical line for small \mu: we perform a direct test of the validity of the method in this case by studying two-color QCD, where the sign problem is absent. The (pseudo)- critical line is found to be analytic around \mu^2 = 0, but a very large precision would be needed at imaginary \mu to correctly predict the location of the critical line at real \mu.