Q-ball formation at the deconfinement temperature in large-$N_c$ QCD

The deconfinement phase transition in large-$N_c$ QCD is studied within the framework of an effective Polyakov-loop model, where the potential has a U(1) symmetry originating in the large-$N_c$ limit of a Z$_{N_c}$-symmetric model. At the critical temperature, the shape of the effective potential allows the existence of Q-balls as position-dependent fluctuations of the Polyakov loop. Q-balls with spherical or axial symmetry are numerically obtained from the equations of motion of the effective model under consideration. The physical properties of these non-topological solitons (mass, charge and size) are discussed, as well as their interpretation in terms of spinning "bubbles", with various shapes, of deconfined matter surrounded by a confined environment.