Speaker
Description
We investigate the photon phase of four-dimensional $\mathbb{Z}_4$ lattice gauge theory. The theory has a plaquette action with two coupling parameters and exhibits various phases depending on their values. Among them is the photon phase, whose low-energy effective theory is believed to be described by Maxwell theory. On the other hand, this lattice gauge theory possesses a duality, and an exact non-invertible symmetry is known to exist along its self-dual line. Assuming that the infrared theory is Maxwell theory, this non-invertible symmetry fixes the gauge coupling, predicting a Coulomb coefficient of $\alpha=1/8$. We perform numerical simulations along the self-dual line and extract the Coulomb coefficient from Polyakov loop correlation functions. We find values in good agreement with the theoretical prediction. Our results provide numerical evidence that the infrared physics of the photon phase is described by Maxwell theory.