Staggered domain wall fermions

We construct domain wall fermions with a staggered kernel and investigate their spectral and chiral properties numerically in the Schwinger model. In some relevant cases we see an improvement of chirality by more than an order of magnitude as compared to usual domain wall fermions. Moreover, we present first results for four-dimensional quantum chromodynamics, where we also observe significant reductions of chiral symmetry violations for staggered domain wall fermions.Comment: 7 pages, 4 figures; v2: Added references; Proceedings for the 34th International Symposium on Lattice Field Theory, University of Southampton, UK, 24-30 July 201

Lattice fermions with complex mass

We present evidence in the Schwinger model that rooted staggered fermions may correctly describe the m<0 sector of a theory with an odd number of flavors. We point out that in QCD-type theories with a complex-valued quark mass every non-chiral action essentially "borrows" knowledge about the theta-transformation properties from the overlap action.Comment: 8 pages, 4 figures. v2: eqn. (20) corrected, figs. 3,4 adjusted, conclusions unchanged. v3: text improved, 2 refs. added (version to appear in PRD

Physics prospects of UV-filtered overlap quarks

Some key features of the overlap operator with a UV-filtered Wilson kernel are discussed. The first part concerns spectral properties of the underlying shifted hermitean Wilson operator and the relation to the observed speedup of the overlap construction. Next, the localization of the filtered overlap and its axial-vector renormalization constant are discussed. Finally, results of an exploratory scaling study for $m_{ud}, m_s$ and $f_\pi, f_K$ are presented.Comment: Talk given at Workshop on Computational Hadron Physics, Nicosia, Cyprus, 14-17 Sep 200

Testing UV-filtered ("fat-link") clover fermions

We investigate filtered clover fermions, built from fat gauge links, both in one-loop perturbation theory and in numerical simulations. We use a variety of filtering recipes (APE, HYP, EXP, HEX), some of which are suitable for a HMC with dynamical fermions. A generic filtering together with a (fat-link) clover term yields fermions with much reduced chiral symmetry breaking.Comment: 7 pages, Lattice 2006 (Quark Masses, Gauge Couplings, and Renormalization

Continuum physics with quenched overlap fermions

We calculate $m_{ud}=(m_u+m_d)/2$, $m_s$, $f_\pi$ and $f_K$ in the quenched continuum limit with UV-filtered overlap fermions. We see rather small scaling violations on lattices as coarse as $a^{-1} \simeq 1 \mathrm{GeV}$ and conjecture that similar advantages would be manifest in unquenched studies.Comment: 10 pages, 5 figures, v2: title changed and other improvements to match published versio