Title: Phases of SU(3) Gauge Theories with Fundamental Quarks via Dirac Spectral Density
Abstract: Distinguishing qualitatively different vacua (or thermal states) of gauge theories has been an interesting topic since such systems were introduced into particle physics. The issue continues to be particularly relevant with quarks in fundamental representation of the gauge group where the screening of strong force by pair production makes Wilson loop considerations ambiguous. In this talk I discuss the proposal to clasify the vacua of these theories via the response of a massless probing (external) quark, and describe the simplest gauge invariant approach of this type that uses the spectral density of Dirac modes. The new phase characterized by bimodal (anomalous) behavior of spectral density is found, arising due to both thermal and light-quark many-flavor effects. I will argue that this phase is expected to occur quite generically in these systems, and is in fact a reality of "real world" strong interactions at RHIC-type temperatures. Dynamics of anomalous phase is that of a deconfined system with broken chiral symmetry.