Scaling test of fermion actions in the Schwinger model

TL;DR

This paper compares the scaling behavior of various fermion actions in the 2D Schwinger model, analyzing physical observables and addressing simulation challenges for overlap fermions.

Contribution

It provides a comparative analysis of Wilson, hypercube, twisted mass, and overlap fermions in the Schwinger model, including methods to improve overlap fermion simulations.

Findings

Different fermion actions exhibit distinct scaling behaviors.

Overlap fermions pose challenges due to low-lying eigenvalues, but solutions are discussed.

Physical observables vary with coupling and fermion mass across actions.

Abstract

We discuss the scaling behaviour of different fermion actions in dynamical simulations of the 2-dimensional massive Schwinger model. We have chosen Wilson, hypercube, twisted mass and overlap fermion actions. As physical observables, the pion mass and the scalar condensate are computed for the above mentioned actions at a number of coupling values and fermion masses. We also discuss possibilities to simulate overlap fermions dynamically avoiding problems with low-lying eigenvalues of the overlap kernel.