Speaker: Mike Teper
Title: SU(N) gauge theories in 3+1 dimensions: glueball spectra, running couplings, $k$-strings, topology.
Abstract: We use lattice simulations to calculate some properties of SU(N) gauge theories in the continuum limit. We do so from N=2 to N=12, enabling an extrapolation to N=infinity. Our main aim is to calculate the lightest glueball masses for all JPC quantum numbers. As a byproduct, we calculate some string tensions, the running of the coupling with an estimate of the Lambda parameter, and some properties of the topological fluctuations of the gauge fields.
Speaker: Francesco Nitti
Title: Holographic theories at finite θ\theta-angle, glueball spectra and instanton condensation
Abstract: In this talk I will discuss a general class of holographic Yang-Mills-like theories at finite theta-angle, described by 5D Einstein-axion-dilaton theories, in which the instanton density operator is dual to the bulk axion field. A non-trivial UV value for the theta-angle induces a running of the axion in the bulk, which backreacts on the geometry. I will discuss the general features of these solutions, and in particular how the axion bacreaction affects the spectrum of excitations and the perturbative stability. I will comment on the possibility of describing instanton condensation in this context.
Speaker: Jeff Greensite
Title: Stable field excitations around static fermions in gauge Higgs theories
Abstract: It is well known that the flux tube between a static quark-antiquark pair has a spectrum of string-like excitations in a confining gauge theory. In this talk I will provide numerical evidence that there is also a spectrum of excitations for the gauge + scalar fields surrounding isolated static fermions in the Higgs phase of gauge Higgs theories, where no color flux tube exists. The examples to date are SU(3) and abelian gauge Higgs theories, the non-relativistic Landau-Ginzburg model, and a U(1) chiral (Smit-Swift) gauge Higgs theory. In all of these cases we show the existence of localized stable excitations of the field surrounding isolated static charges. This would appear as a mass spectrum for isolated (and non-composite)
“elementary” particles. It is conceivable that such excitations might exist in ordinary superconductors, and in the electroweak sector of the Standard Model.
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