Theoretical Particle Physics Seminar – Niels Bohr Institute - University of Copenhagen

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Theoretical Particle Physics Seminar

Speaker: Maria Paola Lombardo (Frascati)

Title: "Many Flavors: Beyond standard QCD and, perhaps, beyond the Standard Model"

Abstract:  Gauge field theories with matter fields have a rich phase structure characterised by different realisation of chiral symmetry, confinement, conformal invariance and asymptotic freedom. Some of the phases
such as the high temperature phase of ordinary QCD can be explored in real experiments, others can offer a paradigm for model builders interested in theory beyond the standard model. This is the case of QCD when the number of fermions is large, but still below the value  at which asymptotic freedom sets in:here,  the theory is conformal and could be used to describe electroweak symmetry breaking. These phenomena are essentially nonperturbative  and lattice calculations are mandatory for  quantitative, reliable results. It occurs, however, that the phase diagram of QCD on the lattice has phases,  and phase transitions with no continuum counterpart, so a lattice study, albeit mandatory,  poses specific challenges. The talk will review the theoretical background and the status  of the phase diagram of QCD, on the lattice and in the continuum, at zero and nonzero temperature,
focusing on the latest lattice results, and highlighting future directions.