Remote Nordic HET seminar: Matteo Bertolini

Speaker: Matteo Bertolini

Title: On fixed-points and phase transitions in five dimensions

Abstract: Supersymmetric gauge theories in five dimensions, although power counting non-renormalizable, are known to be in some cases UV completed by a superconformal field theory (SCFT). Similar results are not available without supersymmetry and it is in fact an open question whether non-supersymmetric CFT exist at all in five dimensions. A concrete way to try and answer this question is to deform known superconformal fixed points by non-supersymmetric relevant deformations and study the end-point of the RG-flow. Recently, a supersymmetry-breaking deformation of one such SCFT, the so-called E_1 theory, was proposed which, at weak gauge coupling, leads to pure SU(2) Yang-Mills and which was conjectured to lead to an interacting CFT at strong coupling. Using both field theory and brane-web techniques, I will show that for large enough gauge coupling a global symmetry is spontaneously broken and the theory enters a new phase which, at infinite coupling, displays an instability. The Yang-Mills and the symmetry broken phases are separated by a phase transition, which can be first or second order. Quantum corrections to this analysis are discussed, as well as possible outlooks.