Spectral Projectors Method for Staggered Fermions

TL;DR

This paper extends the spectral projectors method to staggered fermions, enabling the calculation of topological susceptibility and higher-order coefficients in the theta expansion of the vacuum energy using orthogonal projectors on quasi zero-modes.

Contribution

The authors generalize the spectral projectors method to staggered fermions and derive expressions for topological susceptibility and higher-order theta expansion coefficients.

Findings

Derived an expression for topological susceptibility using staggered fermions.

Generalized the method to compute higher-order coefficients in the theta expansion.

Established a link between the index theorem and staggered Dirac operator.

Abstract

We extend the spectral projectors method to staggered fermions. Applying the index theorem to the staggered Dirac operator it is possible to work out an expression for the topological susceptibility which depends only on the orthogonal projectors on quasi zero-modes, as it has already been done for Dirac-Wilson fermions. Besides, we generalize this method deriving analogous expressions for all higher-order coefficients in the $\theta$-expansion of the vacuum energy.