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We derive chiral Ward identities for lattice QCD with Wilson quarks and $N_\mathrm{f} \geq 3$ flavours, on small lattices with Schr\"odinger functional boundary conditions and vanishingly small quark masses. These identities relate the…

High Energy Physics - Lattice · Physics 2021-08-10 Jochen Heitger , Fabian Joswig , Anastassios Vladikas

We show that it is possible to construct a lattice Schroedinger functional for standard Wilson fermions, where the expectation values of ${\cal R}_5$-even operators are O($a$) improved, up to terms coming from the boundaries.

High Energy Physics - Lattice · Physics 2007-05-23 Roberto Frezzotti , Giancarlo Rossi

We present the current status of a revised strategy to compute the running of renormalized quark masses in QCD with three flavours of massless O(a) improved Wilson quarks. The strategy employed uses the standard finite-size scaling method…

High Energy Physics - Lattice · Physics 2015-08-28 I. Campos , P. Fritzsch , C. Pena , D. Preti , A. Ramos , A. Vladikas

Lattice QCD simulations at small lattice spacings and quark masses close to their physical values are technically challenging. In particular, the simulations can get trapped in the topological charge sectors of field space or may run into…

High Energy Physics - Lattice · Physics 2015-06-05 Martin Lüscher , Stefan Schaefer

We determine non-perturbatively the normalisation constant Z_m*Z_P/Z_A as well as the Symanzik coefficients b_m and b_A-b_P, required in O(a) improved quark mass renormalisation with Wilson fermions. The strategy underlying their…

The vacuum polarization tensor and the corresponding vacuum polarization function are the basis for calculations of numerous observables in lattice QCD. Examples are the hadronic contributions to lepton anomalous magnetic moments, the…

High Energy Physics - Lattice · Physics 2015-03-24 Florian Burger , Grit Hotzel , Karl Jansen , Marcus Petschlies

We present a scaling investigation of some correlation functions in $\Or(a)$ improved quenched lattice QCD. In particular, as one observable the renormalized PCAC quark mass is considered. Others are constructed such that they become the…

High Energy Physics - Lattice · Physics 2015-06-25 Jochen Heitger

The ALPHA collaboration has determined the O(a) improved Wilson quark action for lattice spacings $a\leq 0.1$ fm, in the quenched approximation. We extend this result to coarser lattices, $a\leq 0.17$ fm, and calculate the hadron spectrum…

High Energy Physics - Lattice · Physics 2009-10-30 R. G. Edwards , U. M. Heller , T. R. Klassen

We study the Renormalisation Group (RG) running of the quark mass, for $N_f=3$ QCD with Wilson fermions in a mixed action setup, with standard Schr\"odinger Functional (SF) boundary conditions for sea quarks and chirally rotated…

We present an update of our lattice QCD study of the vacuum polarization function using O$(a)$-improved $N_ {\rm f} =2$ Wilson fermions with increased statistics and a large set of momenta. The resulting points are highly correlated and…

High Energy Physics - Lattice · Physics 2016-02-15 Michele Della Morte , Gregorio Herdoiza , Hanno Horch , Benjamin Jäger , Harvey Meyer , Hartmut Wittig

In these lectures, we discuss different types of renormalization problems in QCD and their non-perturbative solution in the framework of the lattice formulation. In particular the recursive finite size methods to compute the…

High Energy Physics - Phenomenology · Physics 2009-10-30 Rainer Sommer

We carry out the renormalization and the Symanzik O(a)-improvement programme for the static vector current in quenched lattice QCD. The scale independent ratio of the renormalization constants of the static vector and axial currents is…

High Energy Physics - Lattice · Physics 2008-11-26 Filippo Palombi

We non-perturbatively calculate the scale dependence of the static axial current in the Schroedinger functional scheme by means of a recursive finite-size scaling technique, taking the continuum limit in each step. The bare current in the…

High Energy Physics - Lattice · Physics 2008-11-26 Jochen Heitger , Martin Kurth , Rainer Sommer

A systematic treatment of O(a)-improvement in lattice theories with static quarks is presented. The Schr\"odinger functional is discussed and a renormalization condition for the static axial current in the SF-scheme is introduced. Its…

High Energy Physics - Lattice · Physics 2015-06-25 Martin Kurth , Rainer Sommer

We consider O(a) improvement for two flavor lattice QCD. The improvement term in the action is computed non-perturbatively for a large range of the bare coupling. The position of the critical line and higher order lattice artifacts…

High Energy Physics - Lattice · Physics 2009-10-31 Karl Jansen , Rainer Sommer

We develop a strategy for the non-perturbative determination of the O(a)-improvement coefficient c_sw for Wilson fermions with massive sea quarks. The improvement condition is defined via the PCAC relation in the Schr\"odinger functional.…

High Energy Physics - Lattice · Physics 2015-01-28 Patrick Fritzsch , Rainer Sommer , Felix Stollenwerk , Ulli Wolff

We determine the improvement coefficients b_m and b_a-bp in quenched lattice QCD for a range of beta-values, which is relevant for current large scale simulations. At fixed beta, the results are rather sensitive to the precise choices of…

High Energy Physics - Lattice · Physics 2008-11-26 Marco Guagnelli , Roberto Petronzio , Juri Rolf , Stefan Sint , Rainer Sommer , Ulli Wolff

A finite-size technique is employed to compute the normalization constant $Z_A$ of the isovector axial current in lattice QCD. The calculation is carried out in the quenched approximation for values of the bare gauge coupling $g_0$ ranging…

High Energy Physics - Lattice · Physics 2016-09-01 Martin Lüscher , Stefan Sint , Rainer Sommer , Hartmut Wittig

In this review we discuss the general features of maximally twisted lattice QCD. In particular, we illustrate how automatic O(a) improvement can be achieved and how it is possible to set up a lattice regularization scheme where the problem…

High Energy Physics - Lattice · Physics 2009-11-11 R. Frezzotti , G. C. Rossi

The recently proposed construction of chiral fermions on lattices with boundaries is tested in an interacting theory up to first order of perturbation theory. We confirm that, in the bulk of the lattice, the chiral Ward identities take…

High Energy Physics - Lattice · Physics 2011-07-04 Bjorn Leder