New exact upper and lower bounds are derived on the spectrum of the square of the Hermitian Wilson Dirac operator. It is hoped that the derivations and the results will be of help in the search for ways to reduce the cost of simulations using the overlap Dirac operator. The bounds also apply to the Wilson Dirac operator in odd dimensions and are therefore relevant to domain-wall fermions as well.

• Received 5 November 1999

DOI:https://doi.org/10.1103/PhysRevD.61.085015