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The spectral properties of the Wilson-Dirac operator in 2-dimensional QED responsible for the appearance of exceptional configurations in quenched simulations are studied in detail. The mass singularity structure of the quenched functional…

High Energy Physics - Lattice · Physics 2009-10-30 W. Bardeen , A. Duncan , E. Eichten , H. Thacker

The spectral density of euclidean Dirac operator is investigated in partially quenched QCD with arbitrary quark masses. A representation of scalar and pseudoscalar correlators in terms of the spectral density is discussed. The spectral…

High Energy Physics - Phenomenology · Physics 2009-10-31 K. Zyablyuk

I define lattice fermions in five Euclidean dimensions and the corresponding effective theory in four dimensions. The main properties of these theories include the suppression of high momentum modes of the lattice Dirac operator and their…

High Energy Physics - Lattice · Physics 2008-11-26 Artan Borici

Two numerical algorithms for the computation of eigenvalues of Dirac operators in lattice gauge theories are described: one is an accelerated conjugate gradient method, the other one a standard Lanczos method. Results obtained by Cullum's…

High Energy Physics - Lattice · Physics 2009-10-28 Thomas Kalkreuter

Approximating the sum over all gauge field configurations in the QCD partition function by a liquid of instantons, we calculate the spectrum of the Dirac operator for two and three colors and for 0, 1 and 2 flavors. We find a remarkable…

High Energy Physics - Lattice · Physics 2009-10-22 Jacobus Verbaaarschot

We find the lattice spacing dependence of the eigenvalue density of the non-Hermitian Wilson Dirac operator in the $\epsilon$-domain. The starting point is the joint probability density of the corresponding random matrix theory. In addition…

High Energy Physics - Lattice · Physics 2012-02-09 Mario Kieburg , Jacobus J. M. Verbaarschot , Savvas Zafeiropoulos

We discuss the computational problems when analyzing general, non-hermitian matrices and in particular the un-modified Wilson lattice Dirac operator. We report on our experiences with the Implicitly Restarted Arnoldi Method. The eigenstates…

High Energy Physics - Lattice · Physics 2009-10-31 Christof Gattringer , Ivan Hip

We analyze Dirac spectra of two-dimensional QCD like theories both in the continuum and on the lattice and classify them according to random matrix theories sharing the same global symmetries. The classification is different from QCD in…

High Energy Physics - Lattice · Physics 2014-10-22 Mario Kieburg , Jacobus J. M. Verbaarschot , Savvas Zafeiropoulos

Recently, a non-Hermitian chiral random matrix model was proposed to describe the eigenvalues of the QCD Dirac operator at nonzero chemical potential. This matrix model can be constructed from QCD by mapping it to an equivalent matrix model…

High Energy Physics - Lattice · Physics 2009-11-10 G. Akemann , T. Wettig

The eigenvalue spectrum $\rho(\lambda)$ of the Dirac operator is numerically calculated in lattice QCD with 2+1 flavors of dynamical domain-wall fermions. In the high-energy regime, the discretization effects become significant. We subtract…

High Energy Physics - Lattice · Physics 2018-07-11 Katsumasa Nakayama , Hidenori Fukaya , Shoji Hashimoto

We reconsider constraints on the eigenvalue density of the Dirac operator in the chiral symmetric phase of 2 flavor QCD at finite temperature. To avoid possible ultra-violet(UV) divergences, we work on a lattice, employing the overlap Dirac…

High Energy Physics - Lattice · Physics 2013-05-30 Sinya Aoki , Hidenori Fukaya , Yusuke Taniguchi

The low-lying eigenvalue spectrum of the QCD Dirac operator in the epsilon-regime is expected to match with that of chiral Random Matrix Theory (ChRMT). We study this correspondence for the case including sea quarks by performing two-flavor…

High Energy Physics - Lattice · Physics 2012-08-27 JLQCD , TWQCD collaboration , : , H. Fukaya , S. Aoki , T. W. Chiu , S. Hashimoto , T. Kaneko , H. Matsufuru , J. Noaki , K. Ogawa , T. Onogi , N. Yamada

In the $\epsilon$-domain of QCD we have obtained exact analytical expressions for the eigenvalue density of the Dirac operator at fixed $\theta \ne 0$ for both one and two flavors. These results made it possible to explain how the different…

High Energy Physics - Lattice · Physics 2018-07-31 Mario Kieburg , Jacobus Verbaarschot , Tilo Wettig

We study spectra, localization properties and local chirality of eigenvectors of the lattice Dirac operator. We analyze ensembles of quenched SU(3) configurations on both sides of the QCD phase transition. Our Dirac operator is a systematic…

High Energy Physics - Lattice · Physics 2008-11-26 Christof Gattringer , Meinulf Göckeler , P. E. L. Rakow , Stefan Schaefer , Andreas Schäfer

It is shown that the eigenvalue problem for the hermitian Wilson-Dirac operator of for a uniform magnetic field in two dimensions can be reduced to one-dimensional problem described by a relativistic analog of the Harper equation. An…

High Energy Physics - Lattice · Physics 2009-11-07 H. Kurokawa , T. Fujiwara

Nucleon structure functions can be observed in Deep Inelastic Scattering experiments, but it is an outstanding challenge to confront them with fully non-perturbative QCD results. For this purpose we investigate the product of…

High Energy Physics - Lattice · Physics 2010-11-05 W. Bietenholz , N. Cundy , M. Goeckeler , R. Horsley , H. Perlt , D. Pleiter , P. E. L. Rakow , G. Schierholz , A. Schiller , T. Streuer , J. M. Zanotti

We suggest that the lattice Dirac spectra in QCD at finite temperature may be understood using a gaussian unitary ensemble for Wilson fermions, and a chiral gaussian unitary ensemble for Kogut-Susskind fermions. For Kogut-Susskind fermions,…

High Energy Physics - Phenomenology · Physics 2009-10-28 Maciej A. Nowak , Gábor Papp , Ismail Zahed

The overlap operator is a lattice discretization of the Dirac operator of quantum chromodynamics, the fundamental physical theory of the strong interaction between the quarks. As opposed to other discretizations it preserves the important…

High Energy Physics - Lattice · Physics 2014-10-28 James Brannick , Andreas Frommer , Karsten Kahl , Björn Leder , Matthias Rottmann , Artur Strebel

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

We investigate the chiral properties of SU(2) gauge theory with six flavors, i.e. six light Dirac fermions in the fundamental representations by lattice simulation, and point out that the spontaneous breakdown of chiral symmetry does not…

High Energy Physics - Lattice · Physics 2013-11-27 M. Hayakawa , K. -I. Ishikawa , S. Takeda , M. Tomii , N. Yamada