In this paper, we report on results for the s -wave scattering length of the π−K system in the I = 3/2 channel from Nf = 2 + 1 + 1 lattice QCD. The calculation is based on gauge configurations ...generated by the European Twisted Mass Collaboration with pion masses ranging from about 230 to 450 MeV at three values of the lattice spacing. Our main result reads Mπa3/2,phys0 = −0.059 (2). Using chiral perturbation theory we are also able to estimate Mπa1/2,phys0 = 0.163 (3). The error includes statistical and systematic uncertainties, and for the latter in particular errors from the extrapolation to the physical point.
We report on our calculation of the nucleon axial charge g sub(A) in QCD with two flavors of dynamical quarks. A detailed investigation of systematic errors is performed, with a particular focus on ...contributions from excited states to three-point correlation functions. The use of summed operator insertions allows for a much better control over such contamination. After performing a chiral extrapolation to the physical pion mass, we find (ProQuest: Formulae and/or non-USASCII text omitted), in good agreement with the experimental value.
Abstract
We present a lattice QCD investigation of the
$$\rho $$
ρ
-meson with
$$N_\mathrm{{f}}=2+1+1$$
N
f
=
2
+
1
+
1
dynamical quark flavours for the first time. The calculation is performed based ...on gauge configuration ensembles produced by the ETM Collaboration with three lattice spacing values and pion masses ranging from 230 to 500 MeV. Applying the Lüscher method phase-shift curves are determined for all ensembles separately. Assuming a Breit–Wigner form, the
$$\rho $$
ρ
-meson mass and width are determined by a fit to these phase-shift curves. Mass and width combined are then extrapolated to the chiral limit, while lattice artefacts are not detectable within our statistical uncertainties. For the
$$\rho $$
ρ
-meson mass extrapolated to the physical point we find good agreement with experiment. The corresponding decay width differs by about two standard deviations from the experimental value.
We present a lattice QCD investigation of the ρ-meson with Nf=2+1+1 dynamical quark flavours for the first time. The calculation is performed based on gauge configuration ensembles produced by the ...ETM Collaboration with three lattice spacing values and pion masses ranging from 230 to 500 MeV. Applying the Lüscher method phase-shift curves are determined for all ensembles separately. Assuming a Breit–Wigner form, the ρ-meson mass and width are determined by a fit to these phase-shift curves. Mass and width combined are then extrapolated to the chiral limit, while lattice artefacts are not detectable within our statistical uncertainties. For the ρ-meson mass extrapolated to the physical point we find good agreement with experiment. The corresponding decay width differs by about two standard deviations from the experimental value.
We present results for the I = 2 pi pi scattering length using N sub( )f= 2 + 1 + 1 twisted mass lattice QCD for three values of the lattice spacing and a range of pion mass values. Due to the use of ...Laplacian Heaviside smearing our statistical errors are reduced compared to previous lattice studies. A detailed investigation of systematic effects such as discretisation effects, volume effects, and pollution of excited and thermal states is performed. After extrapolation to the physical point using chiral perturbation theory at NLO we obtain M sub( ) pi a sub(0)=-0.0442(2) sub(stat)( sub(-0) super(+4)) sub(sys). Figure not available: see fulltext.
PDF
