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We compute the renormalised four-fermion operator $O^{\Delta S=2}$ using a non-perturbative method recently introduced for determining the renormalisation constants of generic lattice composite operators. Because of the presence of the…

High Energy Physics - Lattice · Physics 2009-10-09 A. Donini , G. Martinelli , C. T. Sachrajda , M. Talevi , A. Vladikas

We compute non-perturbatively the evolution of the twist-2 operators corresponding to the average momentum of non-singlet quark densities. The calculation is based on a finite-size technique, using the Schr\"odinger Functional, in quenched…

High Energy Physics - Lattice · Physics 2009-11-10 A. Shindler , M. Guagnelli , K. Jansen , F. Palombi , R. Petronzio , I. Wetzorke

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.…

High Energy Physics - Lattice · Physics 2008-11-26 M. Guagnelli , K. Jansen , F. Palombi , R. Petronzio , A. Shindler , I. Wetzorke

We present the current status of our computation of quark bilinear renormalization constants for Wilson fermions and Symanzik improved gauge action. Computations are performed in Numerical Stochastic Perturbation Theory. Volumes range from…

High Energy Physics - Lattice · Physics 2010-02-03 M. Brambilla , F. Di Renzo , L. Scorzato

Using Schroedinger Functional methods, we compute the non-perturbative renormalisation and renormalisation group running of several four-fermion operators, in the framework of lattice simulations with two dynamical Wilson quarks. Two…

High Energy Physics - Lattice · Physics 2008-11-26 P. Dimopoulos , G. Herdoiza , F. Palombi , M. Papinutto , C. Pena , A. Vladikas , H. Wittig

We present the first numerical implementation of a non-perturbative renormalization method for lattice operators, based on the study of correlation functions in coordinate space at short Euclidean distance. The method is applied to compute…

High Energy Physics - Lattice · Physics 2009-11-10 V. Gimenez , L. Giusti , S. Guerriero , V. Lubicz , G. Martinelli , S. Petrarca , J. Reyes , B. Taglienti , E. Trevigne

We propose a non-perturbative method for computing the renormalization constants of generic composite operators. This method is intended to reduce some systematic errors, which are present when one tries to obtain physical predictions from…

High Energy Physics - Lattice · Physics 2009-10-09 G. Martinelli , C. Pittori , C. T. Sachrajda , M. Testa , A. Vladikas

We study the non-perturbative determination of the renormalization constants of flavor non-singlet quark bilinear operators on the lattice. The renormalization condition is imposed on correlation functions of bilinear operators in the…

High Energy Physics - Lattice · Physics 2014-11-26 M. Tomii , G. Cossu , S. Hashimoto , J. Noaki

We study RI/MOM renormalization constants of bilinear quark operators for $N_f=4$ and the strong coupling constant for $N_f=2+1+1$ using Wilson twisted-mass fermions. We use the "egalitarian" method to remove H(4) hypercubic artifacts…

High Energy Physics - Lattice · Physics 2011-11-15 B. Blossier , Ph. Boucaud , M. Brinet , F. De Soto , X. Du , M. Gravina , Z. Liu , V. Morenas , O. Pène , K. Petrov , J. Rodríguez-Quintero

We present a 1-loop perturbative calculation of the fermion propagator, up to O(a^2) (a: lattice spacing). The fermions are described by Wilson, clover and twisted-mass actions; for gluons we use Symanzik improved actions (Plaquette,…

High Energy Physics - Lattice · Physics 2010-11-05 Martha Constantinou , Haralambos Panagopoulos , Fotos Stylianou

We present preliminary results of the non-perturbative computation of the RI-MOM renormalisation constants in a mass-independent scheme for the action with Iwasaki glue and four dynamical Wilson quarks employed by ETMC. Our project requires…

We have technically improved the non-perturbative renormalization method, proposed by Martinelli et al., by using quark momentum sources and sinks. Composite two-fermion operators up to three derivatives have been measured for Wilson…

High Energy Physics - Lattice · Physics 2008-11-26 M. Goeckeler , R. Horsley , H. Oelrich , H. Perlt , P. E. L. Rakow , G. Schierholz , A. Schiller

Renormalization constants ($Z$-factors) of vector and axial-vector currents are determined non-perturbatively in quenched QCD for a renormalization group improved gauge action and a tadpole improved clover quark action using the…

We non-perturbatively determine the renormalization factor of the axial vector current in lattice QCD with $N_f=3$ flavors of Wilson-clover fermions and the tree-level Symanzik-improved gauge action. The (by now standard) renormalization…

High Energy Physics - Lattice · Physics 2016-06-29 John Bulava , Michele Della Morte , Jochen Heitger , Christian Wittemeier

A general non-perturbative analysis of the renormalization properties of $\Delta I=3/2$ four-fermion operators in the framework of lattice regularization with Wilson fermions is presented. We discuss the non-perturbative determination of…

High Energy Physics - Lattice · Physics 2011-09-13 A. Donini , V. Giménez , G. Martinelli , M. Talevi , A. Vladikas

We compute non-perturbatively the renormalization constants of quark bilinears on the lattice in the quenched approximation at three values of the coupling beta=6/g_0^2=6.0,6.2,6.4 using both the Wilson and the tree-level improved SW-Clover…

High Energy Physics - Lattice · Physics 2009-10-31 V. Gimenez , L. Giusti , F. Rapuano , M. Talevi

We present new results for the renormalisation and subtraction constants for the four fermion Delta F=2 operators, computed non-perturbatively in the RI-MOM scheme (in the Landau gauge). From our preliminary analysis of the lattice data at…

High Energy Physics - Lattice · Physics 2015-06-25 D. Becirevic , V. Gimenez , V. Lubicz , G. Martinelli , M. Papinutto , J. Reyes

Renormalization constants can be computed by means of Numerical Stochastic Perturbation Theory to two/three loops in lattice perturbation theory, both in the quenched approximation and in the full (unquenched) theory. As a case of study we…

High Energy Physics - Lattice · Physics 2009-11-10 F. Di Renzo , A. Mantovi , V. Miccio , L. Scorzato , C. Torrero

We report on an ongoing non-perturbative computation of RI-MOM scheme renormalization constants for the lattice action with four dynamical flavours currently in use by ETMC. For this goal dedicated simulations with four degenerate sea quark…

High Energy Physics - Lattice · Physics 2015-03-17 P. Dimopoulos , R. Frezzotti , G. Herdoiza , K. Jansen , V. Lubicz , D. Palao , G. C. Rossi

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} =…

High Energy Physics - Lattice · Physics 2015-06-25 M. Guagnelli , K. Jansen , F. Palombi , R. Petronzio , A. Shindler , I. Wetzorke