Theta-Vacuum of the Bosonized Massive Light-Front Schwinger Model

TL;DR

This paper investigates the non-perturbative theta-vacuum structure of the bosonized massive Schwinger model on the light front, revealing how the mass term's non-linearity and zero-mode mixing influence the theta-dependence of physical quantities.

Contribution

It derives the theta-vacuum in the bosonic massive Schwinger model using the Dirac--Bergmann method, highlighting the role of zero modes and non-linear mass effects.

Findings

Theta-vacuum coincides with the massless case.

Mass term becomes highly non-linear due to zero mode constraints.

Zero-mode mixing is essential for accurate theta-dependence calculation.

Abstract

The massive Schwinger model in bosonic representation is quantized on the light front using the Dirac--Bergmann method. The non-perturbative theta- vacuum in terms of coherent states of the gauge-field zero mode is derived and found to coincide with the massless case. On the other hand, the mass term becomes highly non-linear due to the constrained zero mode of the scalar field. A non-trivial mixing between the normal-mode and zero-mode sectors of the model is crucial for the correct calculation of the theta-dependence of the leading order mass correction to the chiral condensate.