Talk presented by Ferdinando Gliozzi

Parallel Session: Confinement II

Tuesday June 29th, 17.00 - 17.20, Fermi Room

When QCD string can break

Abstract: The confining string in presence of dynamical quarks can behave in different ways, depending on the quark masses and on the number N_f N_c of charge species. For light masses and large N_f N_c the creation of quark pairs produces microscopic holes in the world-sheet swept by the string; as a consequence string breaking is invisible in the Wilson loop, while is manifest in operators composed of disjoint sources, as observed in many numerical experiments. Similar arguments apply also to the adjoint string breaking. For havy quarks and small N_f N_c it is expected that the string world-sheet undergoes a transition to a tearing phase, characterized by macroscopic holes which manifest themselves through a string breaking effect also in the Wilson loop.

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