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We present an analysis of the pion-nucleon sigma term on the CLS ensembles with $N_f=2+1$ flavors of $\mathcal{O}(a)$-improved Wilson fermions. We perform a chiral interpolation based on ensembles with pion masses ranging from 130 MeV to…

High Energy Physics - Lattice · Physics 2022-12-23 Andria Agadjanov , Dalibor Djukanovic , Georg von Hippel , Harvey B. Meyer , Konstantin Ottnad , Hartmut Wittig

We calculate the Sheikholeslami-Wohlert coefficient of the O(a) improvement term for Wilson fermions in any representation of the gauge group SU(N) perturbatively at the one-loop level. The result applies to QCD with adjoint quarks and to…

High Energy Physics - Lattice · Physics 2013-06-12 S. Musberg , G. Münster , S. Piemonte

We formulate chiral gauge theories non-perturbatively, using two different cuttoffs for the fermions and gauge bosons. We use a lattice with spacing $b$ to regulate the gauge fields in standard fashion, while computing the chiral fermion…

High Energy Physics - Phenomenology · Physics 2009-09-15 Pilar Hernandez , Raman Sundrum

A non-perturbative determination of the axial current improvement coefficient cA is performed with two flavors of dynamical improved Wilson fermions and plaquette gauge action. The improvement condition is formulated with Schroedinger…

High Energy Physics - Lattice · Physics 2008-11-26 Michele Della Morte , Roland Hoffmann , Rainer Sommer

We study and simulate N=2 supersymmetric Wess-Zumino models in one and two dimensions. For any choice of the lattice derivative, the theories can be made manifestly supersymmetric by adding appropriate improvement terms corresponding to…

High Energy Physics - Lattice · Physics 2008-11-26 Tobias Kaestner , Georg Bergner , Sebastian Uhlmann , Andreas Wipf , Christian Wozar

We analytically derive a decomposition of the lattice fermion determinant for Wilson's Dirac operator with chemical potential into winding sectors, i.e., factors with a fixed number of quarks. Dividing the lattice into four domains, the…

High Energy Physics - Lattice · Physics 2009-01-01 Julia Danzer , Christof Gattringer

We report on the status of an update of our collaboration's previous computation of light and strange quark masses in QCD with $N_{f}=2+1$ dynamical flavours. Bare quark masses are extracted from CLS ensembles, using $O(a)$-improved Wilson…

High Energy Physics - Lattice · Physics 2026-03-30 Gregorio Herdoíza , Fernando P. Panadero , Carlos Pena , Alejandro Sáez

We calculate the PCAC mass for $(2+1)$ flavor full QCD with Wilson-type quarks. We adopt the Small Flow-time eXpansion (SFtX) method based on the gradient flow which provides us a general way to compute correctly renormalized observables…

High Energy Physics - Lattice · Physics 2020-01-07 Atsushi Baba , Shinji Ejiri , Kazuyuki Kanaya , Masakiyo Kitazawa , Asobu Suzuki , Hiroshi Suzuki , Yusuke Taniguchi , Takashi Umeda

A new approach to formulate the fermion field on lattice is introduced by proposing a new Dirac operator on lattice.This approach can eliminate the Fermion doubling problem, preserve the chiral symmetry and get the same dispersion relation…

High Energy Physics - Lattice · Physics 2007-05-23 Bo Feng , Jianming Li , Xingchang Song

Perturbative and non-perturbative results on the renormalization constants of the fermion field and the twist-2 fermion bilinears are presented with emphasis on the non-perturbative evaluation of the one-derivative twist-2 vector and axial…

High Energy Physics - Lattice · Physics 2011-04-01 C. Alexandrou , M. Constantinou , T. Korzec , H. Panagopoulos , F. Stylianou

We present our first set of results for charm physics, using the mixed-action setup introduced in a companion paper. Maximally twisted Wilson valence fermions are used on a sea of non-perturbatively $O(a)$-improved Wilson fermions, made up…

The standard theoretical framework to deal with weak decays of heavy mesons is the so-called weak effective Hamiltonian. It involves the short-distance Wilson coefficients, which depend on the renormalisation scale $\mu$. For specific…

High Energy Physics - Phenomenology · Physics 2016-09-21 Stefan de Boer , Bastian Müller , Dirk Seidel

The renormalization factor and O(a) improvement coefficient of four-quark operators are calculated perturbatively for the improved Wilson fermion action with clover term and the Iwasaki gauge action. With an application to the $K\to\pi\pi$…

High Energy Physics - Lattice · Physics 2015-06-04 Yusuke Taniguchi

We consider the effect of discretization errors on the microscopic spectrum of the Wilson Dirac operator using both chiral Perturbation Theory and chiral Random Matrix Theory. A graded chiral Lagrangian is used to evaluate the microscopic…

High Energy Physics - Lattice · Physics 2015-03-17 G. Akemann , P. H. Damgaard , K. Splittorff , J. J. M. Verbaarschot

We develop the $(1+1)$d lattice $U(1)$ gauge theory in order to define $2$-flavor massless Schwinger model, and discuss its connection with Haldane conjecture. We propose to use the central-branch Wilson fermion, which is defined by…

High Energy Physics - Lattice · Physics 2020-07-01 Tatsuhiro Misumi , Yuya Tanizaki

We study the lattice artefacts of the Wilson Dirac operator for QCD with two colors and fermions in the fundamental representation from the viewpoint of chiral perturbation theory. These effects are studied with the help of the following…

High Energy Physics - Lattice · Physics 2015-08-26 Mario Kieburg , Jacobus J. M. Verbaarschot , Savvas Zafeiropoulos

We construct a 4-d lattice Dirac operator D using a systematical expansion in terms of simple operators on the lattice. The Ginsparg-Wilson equation turns into a system of coupled equations for the expansion coefficients of D. We solve…

High Energy Physics - Lattice · Physics 2010-04-06 Christof Gattringer , Ivan Hip , C. B. Lang

We present a perturbative calculation of the improvement coefficients of SU(2) gauge theory with adjoint representation Wilson-clover fermions and using Schrodinger functional boundary conditions. The computation of the boundary improvement…

High Energy Physics - Lattice · Physics 2011-05-10 Tuomas Karavirta , Anne-Mari Mykkanen , Jarno Rantaharju , Kari Rummukainen , Kimmo Tuominen

We present preliminary results for strangeness form factors of the nucleon computed on the CLS ensembles with $N_f=2+1$ flavors of O($a$)-improved Wilson fermions. Our calculations are performed at two values of the lattice spacing ($a \in…

High Energy Physics - Lattice · Physics 2018-10-26 Dalibor Djukanovic , Harvey Meyer , Konstantin Ottnad , Georg von Hippel , Jonas Wilhelm , Hartmut Wittig

We propose a lattice action including unphysical Wilson fermions with a negative mass m_0 of the order of the inverse lattice spacing. With this action, the exact zero mode of the hermitian Wilson-Dirac operator H_W(m_0) cannot appear and…

High Energy Physics - Lattice · Physics 2009-11-11 JLQCD collaboration , H. Fukaya , S. Hashimoto , K. -I. Ishikawa , T. Kaneko , H. Matsufuru , T. Onogi , N. Yamada