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LPHA A Collaboration Abstract: We present a new normalization condition for the axial current, derived from the PCAC relation with non–vanishing quark mass. This condition is expected to reduce mass effects in the chiral extrapolation of the results for the normalization factor Z A. The application to the two–flavor theory with improved Wilson fermions… (More)
The running of renormalized quark masses is computed in lattice QCD with two massless O(a) improved Wilson quarks. The regularization and flavor independent factor that relates running quark masses to the renor-malization group invariant ones is evaluated in the Schrödinger Functional scheme. Using existing data for the scale r 0 and the pseudoscalar meson… (More)
A non–perturbative determination of the axial current improvement coefficient c A is performed with two flavors of dynamical improved Wilson fermions and plaque-tte gauge action. The improvement condition is formulated with Schrödinger functional boundary conditions and enforced at constant physical volume. Large sensitivity is obtained by using two… (More)
We present and discuss results for cutoff effects in the PCAC masses and the mass dependence of r0 for full QCD and various fermion actions. Our discussion of how one computes mass dependences – here of r0 – is also relevant for comparisons with chiral perturbation theory.
We measure the static potential from Wilson loops constructed using hypercubic blocked (HYP) links. The HYP potential agrees with the potential measured using thin links for distances r/a ≥ 2. We calculated the lowest order perturbative expansion of the lattice Coulomb potential of HYP links. These results are used in analyzing the static potential both on… (More)
We study the quark-antiquark potential of quenched SU(3) lattice gauge theory with the Lüscher-Weisz action. After blocking the gauge fields with the recently proposed hypercubic transformation we compute the Sommer parameter, extract the lattice spacing a and set the scale at 6 different values of the gauge coupling in a range from a = 0.084 fm to 0.136 fm.
The realization of global symmetries can depend on the geometry of the underlying space. In particular, compactification can lead to spontaneous breaking of such symmetries. Four–dimensional QCD with fundamental representation fermions embedded in a space with one compact spatial dimension has a critical length, at which the theory undergoes a phase… (More)
As a feasibility study for a scaling test we investigate the behavior of algorithms for dynamical fermions in the N f = 2 Schrödinger functional at an intermediate volume of 1 fm 4. Simulations were performed using HMC with two pseudo–fermions and PHMC at lattice spacings of approximately 0.1 and 0.07 fm. We show that some algorithmic problems are due to… (More)
We present a new normalization condition for the axial current, which is derived from the PCAC relation with non–vanishing mass. Using this condition reduces the O(r0m) corrections to the axial current normalization constant ZA for an easier chiral extrapolation in the cases, where simulations at zero quark–mass are not possible. The method described here… (More)
Using Schrödinger functional techniques, we determine the coefficient of the clover term necessary for non-perturbative O(a) improvement of hypercubic smeared Wilson fermions on a quenched plaquette action background. Unlike for unsmeared Wilson fermions, the resulting clover coefficients are close to the tree–level value even at coarse lattice spacings,… (More)