Localized eigenmodes of the overlap operator and their impact on the measurement of the topological susceptibility and the chiral condensate
Anna Hasenfratz, Roland Hoffmann, Stefan Schaefer
Journal of High Energy Physics
In a system where chiral symmetry is spontaneously broken, the low energy eigenmodes of the continuum Dirac operator are extended. On the lattice, due to discretization effects, the Dirac operator can have localized eigenmodes that affect physical quantities sensitive to chiral symmetry. While the infrared eigenmodes of the Wilson Dirac operator are usually extended even on coarse lattices, the chiral overlap operator has many localized eigenmodes in the physical region, especially in mixed
... on simulations. Depending on their density, these modes can introduce strong lattice artifacts. The effect can be controlled by changing the parameters of the overlap operator, in particular the clover improvement term and the center of the overlap projection.