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Description
Preliminary results are presented for a novel formulation of the overlap Dirac operator in lattice QCD that employs the diagonal Kenney-Laub (KL) iterates to approximate the matrix sign function. KL iterates require no information about the spectrum of the kernel operator and, when expressed via their partial fraction decomposition, offer a practical alternative for approximating the matrix sign function. We evaluate this approach in a proof-of-concept implementation using quenched lattices at $\beta=6.20$ and two discretizations of the Dirac operator as a kernel, namely the standard Wilson operator and the Brillouin operator. By examining the violation of the Ginsparg-Wilson relation (using a specific metric) and the critical bare quark mass for increasing approximation order, we find that KL-iterates exhibit improved chiral symmetry preservation and computational efficiency compared to the Chebyshev polynomial and Zolotarev rational approaches.