Photon in U(1) Lattice Gauge Theory

Abstract

A Monte Carlo calculation of the spectrum of four-dimensional U(1) lattice gauge theory has been carried out. In the scaling limit $\ensuremath{\beta}\ensuremath{\rightarrow}{\ensuremath{\beta}}_{c}$ massive ${0}^{++}$, ${1}^{+\ensuremath{-}}$, and ${2}^{++}$ states are indicated. On the critical line $\ensuremath{\beta}>{\ensuremath{\beta}}_{c}$ striking evidence is found for a massless photon, and no signal is found for other states.