Related papers: The quenched generating functional for hadronic we…
The effective restoration of $SU(2)_L \times SU(2)_R$ and $U(1)_A$ chiral symmetries of QCD in excited hadrons is reviewed. While the low-lying hadron spectrum is mostly shaped by the spontaneous breaking of chiral symmetry, in the…
The chiral Lagrangian for the Symanzik action through O(a^2) for baryons is obtained. We consider two flavor unquenched and partially quenched lattice theories, allowing for mixed actions in the latter. As an application, we calculate…
Hadronic vacuum polarization at low virtualities limits the precision of experimental tests of the standard model via important physical observables. Here we compute that effect in two-flavor chiral perturbation theory to three loops. Among…
Guided by the large-Nc limit of QCD, we construct the most general chiral resonance Lagrangian that can generate chiral low-energy constants up to O(p^6). By integrating out the resonance fields, the low-energy constants are parametrized in…
Without chiral extrapolation, we achieved a realistic nucleon to (\rho)-meson mass ratio of (m_N/m_\rho = 1.23 \pm 0.04 ({\rm statistical}) \pm 0.02 ({\rm systematic})) in our quenched lattice QCD numerical calculation with staggered…
We report on recent work on the determination of low-energy constants describing Delta{S}=1 weak transitions, in order to investigate the origins of the Delta{I}=1/2 rule. We focus on numerical techniques designed to enhance the statistical…
Hadron masses are computed from quenched twisted mass lattice QCD for a degenerate doublet of up and down quarks with the twist angle set to pi/2, since this maximally twisted theory is expected to be free of linear discretization errors.…
The vector meson mass is extracted from a large sample of partially quenched, two-flavor lattice QCD simulations. For the first time, discretisation, finite-volume and partial quenching artefacts are treated in a unified framework which is…
$K \to \pi$ and $K \to 0$ weak matrix elements of $\Delta S = 1$ operators have been measured in 2+1 flavor domain wall fermion (DWF) QCD on (3 fm)$^3$ lattices with $a^{-1} = 1.73(3)$ GeV. As is well known, using these matrix elements and…
We investigate the limit of vanishing quark mass in quenched lattice QCD with unimproved Wilson fermions at $\beta=6.0$. Exploiting the correlations of propagators at different time slices we extract pion masses extremely close to the…
The status of lattice determinations of quark masses is reviewed (with the exception of m_b). Attempts to extract the low-energy constants in the effective chiral Lagrangian are discussed, with special emphasis on those couplings which are…
The restoration of chiral symmetry at finite density and/or temperature is investigated in a wide class of one-gluon exchange models in the instantaneous approximation. If the effective quark interaction is less divergent than $1/k^2$ for…
We show how one can construct \alert{a simple} exchange functional by extending the well-know local-density approximation (LDA) to finite uniform electron gases. This new generalized local-density approximation (GLDA) functional uses only…
We present a calculation for the $K^+\to\pi^+ \pi^0 $ decay amplitude using a quenched simulation of lattice QCD with the Wilson quark action at $\beta=6/g^2=6.1$. The decay amplitude is extracted from the ratio, the $K\to\pi\pi$…
We report on some recent progress made in understanding weak matrix elements of mesons in the context of the next-to-leading order of the large-Nc approximation to QCD. Specifically, we first use the example of the weak contributions to the…
We present results of a quenched QCD simulation with overlap fermions on a lattice of volume V = 16^3X32 at beta=6.0, which corresponds approximatively to a lattice cutoff of 2 GeV and an extension of 1.4 fm. From the two-point correlation…
A corollary to the Reeh-Schlieder theorem is proved: that the time-ordered Vacuum Expectation Values and the S-matrix of a regularized Lagrangian quantum theory can be approximated by a local operator that uses nonlinear functionals of a…
In the large N_c(number of colors) limit, quenched QCD and QCD are identical. This implies that, in the effective field theory framework, some of the low energy constants in (N_c=3) quenched QCD and QCD are the same up to higher-order…
We have calculated the decay amplitude for the process $K_{S}$ $\to$ $\gamma \gamma$ at one loop order in chiral perturbation theory. As a new improvement we have included the weak mass term which is only relevant for processes with…
In this talk, I address the comparison between results from lattice QCD computations and Chiral Perturbation Theory (ChPT). I briefly discuss how ChPT can be adapted to the much-used quenched approximation and what it tells us about the…