Speaker: Raffaele Savelli, University of Rome "Tor Vergata"
Abstract: Despite the absence of local interactions, Maxwell theory on topologically non-trivial four-manifolds has interesting features. Due to the well-known tension between electromagnetic duality and the gravitational background, global symmetries arising at self-dual points may be plagued by ’t Hooft anomalies, causing the partition function to vanish. I will show that, when the geometry allows for a holomorphic factorization of the partition function, new discrete symmetries emerge, not inherited from dualities, whose anomalies explain why the partition function can be zero even when ordinary duality-symmetries are anomaly free. I will finally discuss the non-invertible generalization of such symmetries and argue that their anomalies can account for a vanishing partition function at non self-dual points. Event recording: