Calculation of the Mass Spectrum of QED-2 in Light-Front Coordinates

TL;DR

This paper numerically calculates the mass spectrum of QED-2 using a light-front Hamiltonian approach, comparing results with lattice calculations and proposing an extrapolation method for removing regularization effects.

Contribution

It introduces a numerical method for calculating the QED-2 spectrum on the light front and compares it with lattice results, including a new extrapolation technique for regularization.

Findings

Spectrum agrees with known results at =0

Agreement at = with small fermion mass

Method effectively extrapolates to remove regularization

Abstract

With the aim of a further investigation of the nonperturbative Hamiltonian approach in gauge field theories, the mass spectrum of QED-2 is calculated numerically by using the corrected Hamiltonian that was constructed previously for this theory on the light front. The calculations are performed for a wide range of the ratio of the fermion mass to the fermion charge at all values of the parameter \hat\theta related to the vacuum angle \theta. The results obtained in this way are compared with the results of known numerical calculations on a lattice in Lorentz coordinates. A method is proposed for extrapolating the values obtained within the infrared-regularized theory to the limit where the regularization is removed. The resulting spectrum agrees well with the known results in the case of \theta=0; in the case of \theta=\pi, there is agreement at small values of the fermion mass (below the phase-transition point).