Lattice fermions with complex mass

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.

Figures (2)

• Figure 1: Scalar condensate in the ${N_{\!f}}=1,2$ dynamical theory versus quark mass. For ${N_{\!f}}=1$ and $m=0$ the overlap condensate successfully reproduces the analytic value by Schwinger. For ${N_{\!f}}=1$ and $m<0$ only the "smart" staggered curve [with an explicit factor $(-1)^\nu$] is correct.
• Figure 3: Scalar condensate and imaginary part of the pseudoscalar condensate versus imaginary mass in the ${N_{\!f}}=1$ dynamical theory, with the definition (\ref{['scalst']}, \ref{['pseust']}) in the staggered case.