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Related papers: Techniques for using the overlap-Dirac operator to…

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We present results of lattice computations using overlap fermions on a twisted mass background. $N_f=2$ full QCD gauge configurations have been produced by the ETM Collaboration with very light pions (down to less than 300 MeV), with small…

High Energy Physics - Lattice · Physics 2009-04-14 Nicolas Garron , Luigi Scorzato

We construct new Ginsparg-Wilson fermions for QCD by inserting an approximately chiral Dirac operator - which involves ingredients of a perfect action - into the overlap formula. This accelerates the convergence of the overlap Dirac…

High Energy Physics - Lattice · Physics 2010-04-05 W. Bietenholz

We present results from simulations of two flavors of dynamical overlap fermions on 8^4 lattices at three values of the sea quark mass and a lattice spacing of about 0.16 fm. We measure the topological susceptibility and the chiral…

High Energy Physics - Lattice · Physics 2009-11-11 Thomas DeGrand , Stefan Schaefer

I show how to avoid a two level nested conjugate gradient procedure in the context of Hybrid Monte Carlo with the overlap fermionic action. The resulting procedure is quite similar to Hybrid Monte Carlo with domain wall fermions, but is…

High Energy Physics - Lattice · Physics 2016-08-25 Herbert Neuberger

Determining the hadron spectrum and hadron properties beyond the ground states is a challenge in lattice QCD. Most of these results have been in the quenched approximation but now we are entering the dynamical era. I review some of the…

Nuclear Theory · Physics 2008-11-26 C. B. Lang

We present results of a quenched QCD simulation with overlap fermions on a lattice of volume V = 16^3X32 at beta=6.0, which corresponds approximatively to a lattice cutoff of 2 GeV and an extension of 1.4 fm. From the two-point correlation…

High Energy Physics - Lattice · Physics 2015-06-25 L. Giusti , C. Hoelbling , C. Rebbi

We discuss the weak coupling expansion of lattice QCD with the overlap Dirac operator. The Feynman rules for lattice QCD with the overlap Dirac operator are derived and the quark self-energy and vacuum polarization are studied at the…

High Energy Physics - Lattice · Physics 2009-10-31 M. Ishibashi , Y. Kikukawa , T. Noguchi , A. Yamada

We report on the status of the dynamical overlap QCD simulation project by the JLQCD collaboration. After completing two-flavor QCD simulation on a 16^3x32 lattice at lattice spacing a 0.12 fm, we started a series of runs with 2+1 flavors.…

High Energy Physics - Lattice · Physics 2008-11-26 JLQCD collaboration , S. Hashimoto , S. Aoki , H. Fukaya , T. Kaneko , H. Matsufuru , J. Noaki , T. Onogi , N. Yamada

We calculate the spectral function of the QCD Dirac operator using the four-dimensional effective operator constructed from the Mobius domain-wall implementation. We utilize the eigenvalue filtering technique combined with the stochastic…

High Energy Physics - Lattice · Physics 2016-01-06 G. Cossu , H. Fukaya , S. Hashimoto , T. Kaneko , J. Noaki

We demonstrate the utility of a spectral approximation to fermion loop operators using low-lying eigenmodes of the hermitian Dirac-Wilson matrix, Q. The investigation is based on a total of 400 full QCD vacuum configurations, with two…

High Energy Physics - Lattice · Physics 2008-11-26 H. Neff , N. Eicker , Th. Lippert , J. W. Negele , K. Schilling

We compute Neuberger's overlap operator by the Lanczos algorithm applied to the Wilson-Dirac operator. Locality of the operator for quenched QCD data and its eigenvalue spectrum in an instanton background are studied.

High Energy Physics - Lattice · Physics 2011-07-19 Artan Borici

On a lattice, we construct an overlap Dirac operator which describes the propagation of a Dirac fermion in external gravity. The local Lorentz symmetry is manifestly realized as a lattice gauge symmetry, while the general coordinate…

High Energy Physics - Lattice · Physics 2009-09-29 Hiroto So , Masashi Hayakawa , Hiroshi Suzuki

We present numerical results for the 2-flavour Schwinger model with dynamical chiral lattice fermions. We insert an approximately chiral hypercube Dirac operator into the overlap formula to construct the overlap hypercube operator. This is…

High Energy Physics - Lattice · Physics 2012-04-26 Wolfgang Bietenholz , Ivan Hip , Stanislav Shcheredin , Jan Volkholz

A new quark-field smearing algorithm is defined which enables efficient calculations of a broad range of hadron correlation functions. The technique applies a low-rank operator to define smooth fields that are to be used in hadron creation…

We present a novel method to compute the overlap Dirac operator at zero and nonzero quark chemical potential. To approximate the sign function of large, sparse matrices, standard methods project the operator on a much smaller Krylov…

High Energy Physics - Lattice · Physics 2010-05-19 Jacques C. R. Bloch , Simon Heybrock

We use low lying eigenvectors of the overlap-Dirac operator as a probe of the QCD vacuum. If instantons play a significant role one would expect the low lying eigenmodes of the overlap-Dirac operator to consist mainly of the mixed ``would…

High Energy Physics - Lattice · Physics 2014-11-17 Robert G. Edwards , Urs M. Heller

The action of the overlap-Dirac operator on a vector is typically implemented indirectly through a multi-shift conjugate gradient solver. The compute-time required depends upon the condition number, $\kappa$, of the matrix that is used as…

High Energy Physics - Lattice · Physics 2010-03-04 W. Kamleh , D. B. Leinweber , A. G. Williams , J. B. Zhang

We study SU(2) gluodynamics at finite temperature near the deconfining phase transition. We create the lattice ensembles using the tadpole improved Luscher-Weisz action. The overlap Dirac operator is used to determine the following three…

High Energy Physics - Lattice · Physics 2008-11-26 V. G. Bornyakov , E. V. Luschevskaya , S. M. Morozov , M. I. Polikarpov , E. M. Ilgenfritz , M. Muller-Preussker

We present preliminary results for the D_s meson spectroscopy study on the 2+1 flavour domain wall fermion lattice configurations, generated with the Iwasaki gauge action at beta=2.13 by the RBC-UKQCD collaboration. The simulations are on…

High Energy Physics - Lattice · Physics 2008-11-26 Chris Allton , Chris Maynard , Aurora Trivini , Robert Tweedie

We report on an ongoing project to parametrize the Fixed-Point Dirac operator for massless quarks, using a very general construction which has arbitrarily many fermion offsets and gauge paths, the complete Clifford algebra and satisfies all…

High Energy Physics - Lattice · Physics 2009-10-31 P. Hasenfratz , S. Hauswirth , K. Holland , T. Jorg , F. Niedermayer , U. Wenger
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