The spectrum of confined QED in 1+1 dimensions is analysed using perturbation theory. The mass spectra of systems made up of massless fermions are calculated toO(e 2) and compared to the mass spectra obtained using nonperturbative methods. Systems containing heavy fermions are also studied and an analogy with the 3+1 dimensional Bag model is pointed out.
Aerts, A. T. M., & Hansson, T. H. (1985). Confined quantum electrodynamics in 1+1 dimensions : a perturbative analysis. Zeitschrift für Physik C: Particles and Fields, 28(4), 537-544. https://doi.org/10.1007/BF01474000