The phase structure of QCD

The phase structure of Nf = 2 QCD is a sensitive probe of the mechanisms of color confinement. In particular the order of the chiral transition can indicate whether the deconfinement corresponds to a change of symmetry of the vacuum (order disorder transition), so that an order parameter exists, or is a continuous crossover at non zero quark mass. Numerical simulations exist on the subject, which, however are not conclusive, since the problem is very demanding computationally. I review the issue, illustrating its importance and the motivations for a bigger effort, and I report on a new analysis which is somehow complementary to the existing ones.