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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(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 MS scheme.(More)
Starting from the QCD Schrödinger functional (SF), we define a family of renormalization schemes for two four-quark operators, which are, in the chiral limit, protected against mixing with other operators. With the appropriate flavour assignments these operators can be interpreted as part of either the ∆F = 1 or ∆F = 2 effective weak Hamiltonians. In view(More)
We discuss the usage of continuous external momenta for computing renormalization 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 simulate two variants of quenched twisted mass QCD (tmQCD), with degenerate Wilson quarks of masses equal to or heavier than half the strange quark mass. We use Ward identities in order to measure the twist angles of the theory and thus check the quality of the tuning of mass parameters to a physics condition which stays constant as the lattice spacing(More)
TheBK parameter is computed in quenched lattice QCD withWilson twisted mass fermions. Two variants of tmQCD are used; in both of them the relevant ∆S = 2 four-fermion operator is renormalised multiplicatively. The renormalisation adopted is non-perturbative, with a Schrödinger functional renormalisation condition. Renormalisation group running is also(More)
The renormalisation group running of the quark mass is determined non-perturbatively for a large range of scales, by computing the step scaling function in the Schrödinger Functional formalism of quenched lattice QCD both with and without O(a) improvement. A one-loop perturbative calculation of the discretisation effects has been carried out for both the(More)
We compute the decay constants for the heavy–light pseudoscalar mesons in the quenched approximation and continuum limit of lattice QCD.Within the Schrödinger Functional framework, we make use of the step scaling method, which has been previously introduced in order to deal with the two scale problem represented by the coexistence of a light and a heavy(More)
We compute the decay constants for the heavy–light pseudoscalar mesons in the quenched approximation and continuum limit of lattice QCD.Within the Schrödinger Functional framework, we make use of the step scaling method, which has been previously introduced in order to deal with the two scale problem represented by the coexistence of a light and a heavy(More)
The BK parameter is computed in quenched lattice QCD with Wilson twisted mass fermions. Two variants of tmQCD are used; in both of them the relevant S = 2 four-fermion operator is renormalised multiplicatively. The renormalisation adopted is non-perturbative, with a Schrödinger functional renormalisation condition. Renormalisation group running is also(More)