2008/03/02 by C. Aubin, Christopher Aubin, Jack Laiho +1 · 1 citation
Physics and Astronomy · #High-Energy Particle Collisions Research #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions #hep-lat
paper · pdf · doi:10.1103/physrevd.77.114501
published as Phys.Rev.D77:114501,2008 · 33 pages, 12 figures
arxiv created 2008/03/02 · openalex publication_date 2008/06/11 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/04
We study discretization effects in a mixed-action lattice theory with domain-wall valence quarks and Asqtad-improved staggered sea quarks. At the level of the chiral effective Lagrangian, discretization effects in the mixed-action theory give rise to two new parameters as compared to the lowest order Lagrangian for rooted-staggered fermions---the residual quark mass mres and the mixed valence-sea meson mass splitting \ensuremathΔmix. We find that mres, which parametrizes explicit chiral symmetry breaking in the mixed-action theory, is approximately one-quarter the size of our lightest valence quark mass on our coarser lattice spacing and of comparable size to that of simulations by the RBC and UKQCD Collaborations. We also find that the size of \ensuremathΔmix is comparable to the size of the smallest of the staggered meson taste splittings measured by the MILC Collaboration. Because lattice artifacts are different in the valence and sea sectors of the mixed-action theory, they give rise to unitarity-violating effects that disappear in the continuum limit, some of which should be described by mixed-action chiral perturbation theory (MA\ensuremathχPT). Such effects are expected to be mild for many quantities of interest but are expected to be significant in the case of the isovector scalar (a0) correlator. Specifically, once the parameters mres, \ensuremathΔmix, and two others that can be determined from the light pseudoscalar meson spectrum are known, the two-particle intermediate state ``bubble'' contribution to the scalar correlator is completely predicted within MA\ensuremathχPT. We find that the behavior of the scalar meson correlator is quantitatively consistent with the MA\ensuremathχPT prediction; this supports the claim that MA\ensuremathχPT describes the dominant unitarity-violating effects in the mixed-action theory and can therefore be used to remove lattice artifacts and recover physical quantities.