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We investigate a variant of hypercubic gauge link smearing where the SU(3) projection is replaced with a normalization to the corresponding unitary group. This smearing is differentiable and thus suitable for use in dynamical fermion…

High Energy Physics - Lattice · Physics 2010-10-27 Anna Hasenfratz , Roland Hoffmann , Stefan Schaefer

SU(2) gauge theory with two fermions transforming under the adjoint representation may appear conformal or almost conformal in the infrared, and is one of the candidate theories for building models for technicolor. Early lattice Monte Carlo…

High Energy Physics - Lattice · Physics 2015-05-20 Tuomas Karavirta , Anne Mykkanen , Jarno Rantaharju , Kari Rummukainen , Kimmo Tuominen

Using Schroedinger functional techniques, we determine the coefficient of the clover term necessary for non-perturbative O(a) improvement of hypercubic smeared Wilson fermions on a quenched plaquette action background. Unlike for unsmeared…

High Energy Physics - Lattice · Physics 2008-11-26 Roland Hoffmann , Anna Hasenfratz , Stefan Schaefer

I have performed scaling tests using quenched spectroscopy of a family of fermion actions which have a hypercubic kinetic term, gauge connections built of smeared links, and an anomalous magnetic moment term. These actions show improved…

High Energy Physics - Lattice · Physics 2010-11-19 MILC Collaboration , T. DeGrand

We discuss a 3-flavour lattice QCD action with clover improvement in which the fermion matrix has single level stout smearing for the hopping terms together with unsmeared links for the clover term. With the (tree-level) Symanzik improved…

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 performed a rough estimate of the non-perturbative value of the clover term coefficient cSW for the APE stout link Wilson fermion. We varied the number of smearings from Nsmear=1 to 6 and adopted beta values roughly corresponding to the…

High Energy Physics - Lattice · Physics 2013-03-04 Yusuke Taniguchi

The research of strongly coupled beyond-the-standard-model theories has generated significant interest in non-abelian gauge field theories with different number of fermions in different representations. Motivated by the increased interest…

High Energy Physics - Lattice · Physics 2010-11-11 Anne Mykkanen , Jarno Rantaharju , Kari Rummukainen , Tuomas Karavirta , Kimmo Tuominen

We present results of quenched $SU(3)$ hadron spectroscopy comparing $\order(a)$ improved Wilson (Clover) fermions with conventional Wilson fermions. The configurations were generated using an $\order(a^2)$ improved 6-link $SU(3)$ pure…

High Energy Physics - Lattice · Physics 2010-01-18 Sara Collins , Robert G. Edwards , Urs M. Heller , John Sloan

The improved Wilson quark action - the clover action - is constructed to have smaller discretization errors than the normal Wilson quark action. We test this in a quenched spectroscopy computation on 6 lattice ensembles with spacings from…

High Energy Physics - Lattice · Physics 2007-05-23 Sara Collins , R. G. Edwards , U. M. Heller , John Sloan

Clover improvement is the standard choice for lattice simulations of QCD, when the lattice artefacts coming from Wilson fermions have to be reduced. However, the clover improvement is not limited to QCD, but can be applied to a wider range…

High Energy Physics - Lattice · Physics 2013-11-26 S. Musberg , G. Münster , S. Piemonte

We calculate non-perturbatively the coefficient c_sw required for O(a) improvement of the SU(3) gauge theory with Nf = 2 fermions in the two-index symmetric (sextet) representation. For the calculations we impose the standard improvement…

High Energy Physics - Lattice · Physics 2017-01-13 Martin Hansen

We discuss an action in which the fermion matrix has single level stout smearing for the hopping terms together with unsmeared links for the clover term. With the (tree level) Symanzik improved gluon action this constitutes the Stout Link…

A Lie-algebra based recipe for smoothing gauge links in lattice field theory is presented, building on the matrix logarithm. With or without hypercubic nesting, this LOG/HYL smearing yields fat links which are differentiable w.r.t. the…

High Energy Physics - Lattice · Physics 2009-08-05 Stephan Durr

We discuss the tuning of the anisotropic clover action and Symanzik-improved gauge action in lattice perturbation theory. The fermion action is constructed from stout-smeared spatial links, which complicates the calculation considerably. In…

High Energy Physics - Lattice · Physics 2010-01-21 Justin Foley , Colin Morningstar

The chiral properties of lattice fermions can be improved by altering either their fermion-gauge coupling or the pure gauge part of the action (or both). Using both perturbation theory and nonperturbative simulation, we compare a simple…

High Energy Physics - Lattice · Physics 2016-09-01 Thomas DeGrand , Anna Hasenfratz , Tamas G. Kovacs

I describe studies of quenched spectroscopy, using crude approximations to fixed point actions for fermions interacting with SU(3) gauge fields. These actions have a hypercubic kinetic term and a complicated lattice anomalous magnetic…

High Energy Physics - Lattice · Physics 2009-10-30 T. DeGrand

We determine the improvement factor $c_{SW}$ in one-loop lattice perturbation theory for the plaquette and Symanzik improved gauge actions. The fermionic action is ${\mathcal{O}(a)}$ clover improved with one-time stout smearing. $c_{SW}$ is…

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

We present a framework for phenomenological lattice QCD calculations which makes use of a tree level Symanzink improved action for gluons and stout-link Wilson fermions. We give details of our efficient HMC/RHMC algorithm and present a…

High Energy Physics - Lattice · Physics 2009-02-10 S. Durr , Z. Fodor , C. Hoelbling , R. Hoffmann , S. D. Katz , S. Krieg , T. Kurth , L. Lellouch , T. Lippert , K. K. Szabo , G. Vulvert

First results from simulations of improved actions for both gauge fields and staggered fermion fields in three dimensional QCD are presented. This work provides insight into some issues of relevance to lattice theories in four dimensions.…

High Energy Physics - Lattice · Physics 2011-07-19 Howard D. Trottier
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