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We compute the leading QED corrections to the hadronic vacuum polarization (HVP) of the photon, relevant for the determination of leptonic anomalous magnetic moments, al. We work in the electroquenched approximation and use dynamical QCD configurations generated by the CLS initiative with two degenerate flavors of nonperturbatively O(a)-improved Wilson fermions. We consider QEDL and QEDM to deal with the finite-volume zero modes. We compare results for the Wilson loops with exact analytical determinations. In addition we make sure that the volumes and photon masses used in QEDM are such that the correct dispersion relation is reproduced by the energy levels extracted from the charged pions two-point functions. Finally we compare results for pion masses and the HVP between QEDL and QEDM. For the vacuum polarization, corrections with respect to the pure QCD case, at fixed pion masses, turn out to be at the percent level.

We report on a non-perturbative determination of the parameters of the lattice Heavy Quark Effective Theory (HQET) Lagrangian and of the time component of the heavy-light axial-vector current with Nf = 2 flavors of massless dynamical quarks. The effective theory is considered at the 1/ mh order, and the heavy mass mh covers a range from slightly above the charm to beyond the beauty region. These HQET parameters are needed to compute, for example, the b-quark mass, the heavy-light spectrum and decay constants in the static approximation and to order 1/ mh in HQET. The determination of the parameters is done non-perturbatively. The computation reported in this paper uses the plaquette gauge action and two different static actions for the heavy quark described by HQET. For the light-quark action we choose non-perturbatively O( a)-improved Wilson fermions.[Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Abstract: We discuss kinematical enhancements of cutoff effects at short and intermediate distances. Starting from a pedagogical example with periodic boundary conditions, we switch to the case of the Schrödinger functional, where the theoretical analysis is checked by precise numerical data with dynamical -improved Wilson quarks. Finally we present an improved determination of the renormalization of the axial current in that theory. [Copyright &y& Elsevier]

Abstract: We simulate two-dimensional QED with two degenerate Wilson fermions and plaquette gauge action. As a consequence of the Mermin–Wagner theorem, in the continuum limit chiral symmetry is realized à la Wigner. This property affects also the size of the cutoff effects. That can be understood in view of the fact that the leading lattice artifacts are described, in the continuum Symanzik effective theory, by chirality breaking terms. In particular, vacuum expectation values of non-chirality-breaking operators are expected to be improved in the chiral limit. We provide a numerical confirmation of this expectation by performing a scaling test. [Copyright &y& Elsevier]

Abstract: The running of renormalized quark masses is computed in lattice QCD with two flavors of massless improved Wilson quarks. The regularization and flavor independent factor that relates running quark masses to the renormalization group invariant ones is evaluated in the Schrödinger functional scheme. Using existing data for the scale and the pseudoscalar meson masses, we define a reference quark mass in QCD with two degenerate quark flavors. We then compute the renormalization group invariant reference quark mass at three different lattice spacings. Our estimate for the continuum value is converted to the strange quark mass with the help of chiral perturbation theory. [Copyright &y& Elsevier]

Abstract: We report our final estimate of the b-quark mass from lattice QCD simulations using Heavy Quark Effective Theory non-perturbatively matched to QCD at . Treating systematic and statistical errors in a conservative manner, we obtain after an extrapolation to the physical point. [Copyright &y& Elsevier]