Bound states for Overlap and Fixed Point Actions close to the chiral limit

TL;DR

This paper investigates the properties of overlap and fixed point Dirac operators for massive fermions in the two-flavor lattice Schwinger model, focusing on bound state masses near the chiral limit and analyzing stability issues.

Contribution

It provides a detailed comparison of bound state masses obtained from overlap and fixed point operators with continuum models, highlighting stability challenges near the chiral limit.

Findings

Bound state masses are determined down to small fermion masses.

Fixed point operator stability issues are dominated by finite size effects.

Comparison with continuum models shows good agreement at larger masses.

Abstract

We study the overlap and the fixed point Dirac operators for massive fermions in the two-flavor lattice Schwinger model. The masses of the triplet (pion) and singlet (eta) bound states are determined down to small fermion masses and the mass dependence is compared with various continuum model approximations. Near the chiral limit, at very small fermion masses the fixed point operator has stability problems, which in this study are dominated by finite size effects,