Light hadron spectroscopy with two flavors of O(a) improved dynamical quarks

Abstract

We present a high statistics study of the light hadron spectrum and quark masses in QCD with two flavors of dynamical quarks. Numerical simulations are carried out using the plaquette gauge action and the O(a)-improved Wilson quark action at ␤ϭ5.2, where the lattice spacing is found to be aϭ0.0887(11) fm from the meson mass, on a 20 3 ϫ48 lattice. At each of five sea quark masses corresponding to m PS /m V Ӎ0.8-0.6, we generate 12 000 trajectories using a symmetrically preconditioned Hybrid Monte Carlo algorithm. Finite spatial volume effects are investigated employing 12 3 ϫ48, 16 3 ϫ48 lattices. We also perform a set of simulations in quenched QCD with the same lattice actions at a similar lattice spacing to those for the full QCD runs. In the meson sector we find clear evidence of sea quark effects. The J parameter increases for lighter sea quark masses, and the full QCD meson masses are systematically closer to experiment than in quenched QCD. Careful finite-size studies are made to ascertain that these are not due to finite-size effects. Evidence of sea quark effects is less clear in the baryon sector due to larger finite-size effects. We also calculate light quark masses and find m ud MS (2 GeV)ϭ3.223(Ϫ0.069 ϩ0.046) MeV and m s MS (2 GeV)ϭ84.5(Ϫ1.7 ϩ12.0) MeV which are about 20% smaller than in quenched QCD.

Light meson physics from maximally twisted mass lattice QCD

“…For pioneering work for N f = 2 flavour lattice QCD see refs. [37][38][39]. We use data for the charged pseudo scalar meson mass m PS and the decay constant f PS computed in a range of 280 MeV m PS 650 MeV.…”

BK-parameter fromNf=2twisted mass lattice QCD

“…For instance in the case β = 3.9 one gets Z 1−loop,RGI V A+AV = 0.422, if the perturbative gauge coupling is set to g 2 0 / P ( P is the plaquette expectation value), or Z 1−loop,RGI V A+AV = 0.675, if the perturbative gauge coupling is set to the "boosted" value corresponding to the prescription of ref. [46]. These numbers should be compared with the values in Table 4.…”

Chiral corrections and lattice QCD results for f/f and Δm/Δm

“…We also kindly acknowledge the correspondance with T. Kaneko concerning the details on the results of ref. [21]. The research of S.F., P.S., and J.Z.…”

“…We therefore take α = 0.16 (5). From an extensive study of the light hadrons with two flavors of dynamical quarks by the JLQCD and the CP-PACS collaborations [21], one has f K /f π = 1.16(2), i.e. β = 0.16 (2).…”