Investigating confinement in dually transformed U(1) lattice gauge theory

The dually transformed path integral of four-dimensional U(1) lattice gauge theory is used for the calculation of expectation values in the presence of external charges. Applying the dual simulation to flux tubes for charge distances up to around 20 lattice spacings, we find a deviation from the behavior of a dual type-II superconductor in the London limit at large distances. The roughening of the flux tube agrees with the effective string picture of confinement. Further we show that finite temperature effects are negligible for time extents larger than the charge distance. Finally we analyze the different contributions to the total energy of the electromagnetic field. The parallel component of the magnetic field turns out to have the strongest influence on the deviation from the linear behavior at small charge distances.