Lattice fermions with complex mass

TL;DR

This paper investigates the use of rooted staggered fermions in the Schwinger model, suggesting they can accurately represent the negative mass sector and discussing implications for QCD with complex quark masses.

Contribution

It provides evidence that rooted staggered fermions can correctly describe certain sectors in the Schwinger model and explores their relation to overlap actions in QCD with complex masses.

Findings

Rooted staggered fermions may correctly describe the m<0 sector.

Non-chiral actions inherit theta-transformation properties from overlap actions.

Implications for QCD theories with complex quark masses.

Abstract

We present evidence in the Schwinger model that rooted staggered fermions may correctly describe the m<0 sector of a theory with an odd number of flavors. We point out that in QCD-type theories with a complex-valued quark mass every non-chiral action essentially "borrows" knowledge about the theta-transformation properties from the overlap action.