Related papers: Electromagnetic Corrections in Staggered Chiral Pe…
To one-loop order and $O(\alpha_{em})$, the electromagnetic mass splittings of $\pi$, $a_1$, $K$, $K_1(1400)$, and $K^*(892)$ are calculated in the framework of $U(3)_L\times U(3)_R$ chiral field theory. The logarithmic divergences emerging…
In a recent paper [hep-lat/0701012] we presented precise lattice QCD results of our European Twisted Mass Collaboration (ETMC). They were obtained by employing two mass-degenerate flavours of twisted mass fermions at maximal twist. In the…
[This version is a minor revision of a previously submitted preprint. Only references have been changed.] We describe a technique for constructing the effective chiral theory for quenched QCD. The effective theory which results is a…
In this talk we briefly review how the unitarization of Chiral Perturbation Theory with dispersion relations can successfully describe the meson-meson scattering data and generate light resonances, whose mass, width and nature can be…
We report our light hadron mass calculation based on an increased statistics of 250 quenched gauge configurations on a (48^3 \times 64) lattice at (\beta = 6.5). Quark propagators are calculated for each of these configurations with…
We update our determinations of $f_{D^+}$, $f_{D_s}$, $f_K$, and quark mass ratios from simulations with four flavors of HISQ dynamical quarks. The availability of ensembles with light quarks near their physical mass means that we can…
Three topics about the application of quenched chiral perturbation theory to matter fields are studied. It is proved that the hairpin axial current couplings in quenched chiral perturbation theories do not contribute to the quenched chiral…
We extend our lagrangian technique for chiral perturbation theory for quenched QCD to include theories in which only some of the quarks are quenched. We discuss the relationship between the partially quenched theory and a theory in which…
The quenched approximation for QCD is, at present and in the foreseeable future, unavoidable in lattice calculations with realistic choices of the lattice spacing, volume and quark masses. In this talk, I review an analytic study of the…
Using the pole shifting procedure of the modified quenched approximation (MQA) to cure the exceptional configuration problem, accurate hadron hadron spectrum calculations can be obtained at very light quark mass. Here we use the MQA to…
We study the quark mass expansion of the magnetic moments of the nucleon in a chiral effective field theory including nucleons, pions and delta resonances as explicit degrees of freedom. We point out that the usual powercounting applied so…
We calculate the form factors for the semileptonic decays of heavy-light pseudoscalar mesons in partially quenched staggered chiral perturbation theory (\schpt), working to leading order in $1/m_Q$, where $m_Q$ is the heavy quark mass. We…
We show that maximally twisted mass fermions can be employed to regularize on the lattice the fully unquenched QCD+QED theory with vanishing $\theta$-term. We discuss how the critical mass of the up and down quarks can be conveniently…
We compare the linear meson model and chiral perturbation theory in next to leading order in the quark mass expansion. In particular, we compute the couplings L_4--L_8 of chiral perturbation theory as functions of the parameters of the…
At the precision reached in current lattice QCD calculations, electromagnetic effects are becoming numerically relevant. We will present preliminary results for electromagnetic corrections to light hadron masses, based on simulations in…
We demonstrate the viability of improved staggered light quarks in studies of heavy-light systems. Our method for constructing heavy-light operators exploits the close relation between naive and staggered fermions. The new approach is…
The MILC collaboration's simulations with improved staggered quarks are being extended with runs at a lattice spacing of 0.06 fm with quark masses down to one tenth the strange quark mass. We give a brief introduction to these new…
We report the final results of the CP-PACS calculation for the quenched light hadron spectrum with the Wilson quark action. Our data support the presence of quenched chiral singularities, and this motivates us to use mass formulae based on…
We consider partially quenched, mixed chiral perturbation theory with staggered sea and Ginsparg-Wilson valence quarks in order to extract a chiral-continuum extrapolation expression for the vector meson mass up to order O(a^2), at one-loop…
We present results on the sum of the masses of light and strange quark using improved staggered quarks. Our calculation uses 2+1 flavours of dynamical quarks. The effects of the dynamical quarks are clearly visible.