We explain how masses and matrix elements can be computed in lattice QCD using Schrödinger functional boundary conditions. Numerical results in the quenched approximation demonstrate that good precision can be achieved. For a statistical sample of the same size, our hadron masses have a precision similar to what is achieved with standard methods, but for… (More)
We define a family of Schrödinger Functional renormalization schemes for the four-quark multiplicatively renormalizable operators of the ∆F = 1 and ∆F = 2 effective weak Hamiltonians. Using the lattice regularization with quenched Wilson quarks, we compute non-perturbatively the renormalization group running of these operators in the continuum limit in a… (More)
We present results for the reference scale r 0 in SU(3) Lattice Gauge Theory for β = 6/g 2 0 in the range 5.7 ≤ β ≤ 6.57. The high relative accuracy of 0.3–0.6% in r 0 /a was achieved through good statistics, the application of a multi-hit procedure and a variational approach in the computation of Wilson loops. A precise definition of the force used to… (More)
We compute charm and bottom quark masses in the quenched approximation and in the continuum limit of lattice QCD. We make use of a step scaling method, previously introduced to deal with two scale problems, that allows to keep the lattice cutoff always greater than the quark mass. We determine the RGI quark masses and make the connection to the M S scheme.… (More)
We give a continuum limit value of the lowest moment of a twist-2 operator in pion states from non-perturbative lattice calculations. We find that the non-perturbatively obtained renormalization group invariant matrix element is x RGI = 0.179(11), which corresponds to x MS (2 GeV) = 0.246(15). In obtaining the renormalization group invariant matrix element,… (More)
We investigate finite size effects of the pion matrix element of the non-singlet, twist-2 operator corresponding to the average momentum of non-singlet quark densities. Using the quenched approximation, they come out to be surprisingly large when compared to the finite size effects of the pion mass. As a consequence, simulations of corresponding nucleon… (More)
We discuss the usage of continuous external momenta for computing renor-malization factors as needed to renormalize operator matrix elements. These kind of external momenta are encoded in special boundary conditions for the fermion fields. The method allows to compute certain renormalization factors on the lattice that would have been very difficult, if not… (More)
We report on a parallelized implementation of SSOR preconditioning for O(a) improved lattice QCD with Schrödinger functional boundary conditions. Numerical simulations in the quenched approximation at parameters in the light quark mass region demonstrate that a performance gain of a factor ∼ 1.5 over even-odd preconditioning can be achieved.
We show that the renormalization factor relating the renormalization group invariant quark masses to the bare quark masses computed in lattice QCD can be determined non-perturbatively. The calculation is based on an extension of a finite-size technique previously employed to compute the running coupling in quenched QCD. As a by-product we obtain the… (More)
We present the first results obtained with a Hybrid Molecular Dynamics algorithm applied to an N = 1 SU(2) Super-Yang–Mills on the lattice. We derive the Hamilton equations of motion for the system with Wilson gluinos and present preliminary results on small lattices.