On the suitability of the Brillouin action as a kernel to the overlap procedure

Understand

We investigate the Brillouin action in terms of its suitability as a kernel to the overlap procedure, with a view on both heavy and light quark physics.

• We use the diagonal elements of the Kenney-Laub family of iterations for the sparse matrix sign function, since they grow monotonically and facilitate cascaded preconditioning strategies with different rational approximations to the sign function.
• We find that the overlap action with the Brillouin kernel is significantly better localized than the version with the Wilson kernel.