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Related papers: O(a^2) cutoff effects in Wilson fermion simulation…

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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 behaviour of the pion transition form factor for the process $\gamma^\star\gamma \to \pi^0$ and $\gamma^\star\gamma^\star\to \pi^0$ at space-like values of photon momenta is estimated within the nonlocal covariant quark-meson model. The…

High Energy Physics - Phenomenology · Physics 2007-05-23 A. E. Dorokhov

The electromagnetic form factors provide important hints for the internal structure of the nucleon and continue to be of major interest for experimentalists. For an intermediate range of momentum transfers the form factors can be calculated…

We discuss the use of Wilson fermions with twisted mass for simulations of QCD thermodynamics. As a prerequisite for a future analysis of the finite-temperature transition making use of automatic O(a) improvement, we investigate the phase…

High Energy Physics - Lattice · Physics 2009-04-14 E. -M. Ilgenfritz , M. Müller-Preußker , M. Petschlies , K. Jansen , M. P. Lombardo , O. Philipsen , L. Zeidlewicz , A. Sternbeck

We test the reweighting of the quark determinant of O(a) improved Wilson fermions in the domain-decomposed hybrid Monte-Carlo algorithm. Specifically, we implement a reweighting in a twisted-mass parameter proposed by Palombi and L\"uscher…

High Energy Physics - Lattice · Physics 2011-11-17 Chuan Miao , Harvey B. Meyer , Hartmut Wittig

We study the impact of explicit chiral symmetry breaking of lattice Wilson fermions on mesonic correlators in the epsilon-regime using Wilson chiral perturbation theory. We generalize the epsilon-expansion of continuum chiral perturbation…

High Energy Physics - Lattice · Physics 2009-04-29 Oliver Bar , Silvia Necco , Stefan Schaefer

We present a calculation of pion electromagnetic and scalar form factors in two-flavor QCD with the non-perturbatively O(a)-improved Wilson fermion. Chiral extrapolation of the corresponding charge radius is discussed based on the chiral…

We present the results of an extended scaling test of quenched Wilson twisted mass QCD. We fix the twist angle by using two definitions of the critical mass, the first obtained by requiring the vanishing of the pseudoscalar meson mass m_PS…

High Energy Physics - Lattice · Physics 2007-05-23 K. Jansen , M. Papinutto , A. Shindler , C. Urbach , I. Wetzorke

We present results from simulations using 2 flavours of O(a)-improved Wilson quarks whose masses are about 1/3 of the physical strange quark mass. We present new data on the mass of the singlet pseudoscalar meson and evidence of the onset…

High Energy Physics - Lattice · Physics 2008-11-26 CR Allton , A Hart , D Hepburn , AC Irving , B Joo , C McNeile , C Michael , SV Wright

We study the leading discretization errors for staggered fermions by first constructing the continuum effective Lagrangian including terms of O(a^2), and then constructing the corresponding effective chiral Lagrangian. The terms of O(a^2)…

High Energy Physics - Lattice · Physics 2008-11-26 Weonjong Lee , Stephen Sharpe

In the framework of relativistic SU(2)_f baryon chiral perturbation theory we calculate the volume dependence of the nucleon mass up to and including O(p^4). Since the parameters in the resulting finite size formulae are fixed from the pion…

High Energy Physics - Lattice · Physics 2010-04-06 A. Ali Khan , T. Bakeyev , M. Göckeler , T. R. Hemmert , R. Horsley , A. C. Irving , B. Joó , D. Pleiter , P. E. L. Rakow , G. Schierholz , H. Stüben

The charm-quark mass is typically not so far from the cutoff 1/a in lattice simulations. Its determinant may then potentially introduce large cutoff effects. We choose the O(a)-improved Wilson formulation and compute the vacuum polarization…

High Energy Physics - Lattice · Physics 2012-03-13 Andreas Athenodorou

Partially quenched Quantum Chromodynamics with Wilson fermions on a lattice is considered in the framework of chiral perturbation theory. Two degenerate quark flavours are associated with a chirally twisted mass term. The pion masses and…

High Energy Physics - Lattice · Physics 2010-12-17 Gernot Münster , Christian Schmidt , Enno E. Scholz

We investigate the low-lying eigenvalues of the improved Wilson-Dirac operator in the Schroedinger functional with two dynamical quark flavors. At a lattice spacing of approximately 0.1 fm we find more very small eigenvalues than in the…

High Energy Physics - Lattice · Physics 2009-11-10 M. Della Morte , R. Hoffmann , F. Knechtli , U. Wolff

The chiral Lagrangian describing the low-energy behavior of N_f=2+1+1 twisted mass lattice QCD is constructed through O(a^2). In contrast to existing results the effects of a heavy charm quark are consistently removed, leaving behind a…

High Energy Physics - Lattice · Physics 2014-09-05 Oliver Baer , Ben Horz

We present a lattice calculation of the electromagnetic form factor of the pion obtained using the tree-level Symanzik improved gauge action with two flavors of dynamical twisted Wilson quarks. The simulated pion masses range approximately…

High Energy Physics - Lattice · Physics 2009-11-06 R. Frezzotti , V. Lubicz , S. Simula

We present a first Wilson twisted mass fermion calculation of the matrix element between pion states of the twist-2 operator, which is related to the the lowest moment < x > of the valence quark parton distribution function in a pion. Using…

High Energy Physics - Lattice · Physics 2009-11-11 S. Capitani , K. Jansen , M. Papinutto , A. Shindler , C. Urbach , I. Wetzorke

I review the theoretical foundations, properties as well as the simulation results obtained so far of a variant of the Wilson lattice QCD formulation: Wilson twisted mass lattice QCD. Emphasis is put on the discretization errors and on the…

High Energy Physics - Lattice · Physics 2008-05-19 A. Shindler

The twisted space-time reduced model of large $N$ QCD with various flavours of adjoint Wilson fermions is constructed applying the symmetric twist boundary conditions with flux $k$. The models with one and two flavours show distinctive…

High Energy Physics - Lattice · Physics 2017-08-23 Antonio González-Arroyo , Masanori Okawa

Qualitative features of Ginsparg-Wilson fermions, as formulated by Neuberger, coupled to two dimensional U(1) gauge theory are studied. The role of the Wilson mass parameter in changing the number of massless flavors in the theory and its…

High Energy Physics - Lattice · Physics 2009-10-31 Shailesh Chandrasekharan
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