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We investigate the eigenvalue spectrum of the staggered Dirac matrix in SU(3) and U(1) gauge theory as well as in full QCD with two colors and finite chemical potential. Along the strong-coupling axis up to the phase transition, the…

高能物理 - 格点 · 物理学 2008-11-26 Elmar Bittner , Maria-Paola Lombardo , Harald Markum , Rainer Pullirsch

We study the eigenvalues of Dirac operators in QCD with two mass degenerate dynamical fermions. The gauge configurations have been obtained with HMC and the so-called Chirally Improved fermionic action. We compare eigenvalues obtained for…

高能物理 - 格点 · 物理学 2009-04-14 Martina Joergler , C. B. Lang

It was established that distribution of the near-zero modes of the Dirac operator is consistent with the Chiral Random Matrix Theory (CRMT) and can be considered as a consequence of spontaneous breaking of chiral symmetry (SBCS) in QCD. The…

高能物理 - 格点 · 物理学 2018-04-18 M. Catillo , L. Ya. Glozman

Complete spectra of the staggered Dirac operator $\Dirac$ are determined in quenched four-dimensional $SU(2)$ gauge fields, and also in the presence of dynamical fermions. Periodic as well as antiperiodic boundary conditions are used. An…

高能物理 - 格点 · 物理学 2009-10-22 Thomas Kalkreuter

Quark spectra in QCD are linked to fundamental properties of the theory including the identification of pions as the Goldstone bosons of spontaneously broken chiral symmetry. The lattice Overlap-Dirac operator provides a nonperturbative,…

高能物理 - 理论 · 物理学 2009-10-31 Robert G. Edwards , Urs M. Heller , Joe Kiskis , Rajamani Narayanan

We investigate the eigenvalue spectrum of the staggered Dirac matrix in SU(3) gauge theory and in full QCD as well as in quenched U(1) theory on various lattice sizes. As a measure of the fluctuation properties of the eigenvalues, we…

高能物理 - 格点 · 物理学 2007-05-23 B. A. Berg , E. Bittner , M. -P. Lombardo , H. Markum , R. Pullirsch , T. Wettig

In the first part of these lectures we discuss the infrared limit of the spectrum of the QCD Dirac operator. We discuss the global symmetries of the QCD partition function and show that the Dirac spectrum near zero virtuality is determined…

高能物理 - 唯象学 · 物理学 2007-05-23 J. J. M. Verbaarschot

We analyze how individual eigenvalues of the QCD Dirac operator at nonzero quark chemical potential are distributed in the complex plane. Exact and approximate analytical results for both quenched and unquenched distributions are derived…

高能物理 - 格点 · 物理学 2008-11-26 G. Akemann , J. Bloch , L. Shifrin , T. Wettig

A new formulation of chiral fermions on the lattice is presented. It is a version of overlap fermions, but built from the computationally efficient staggered fermions rather than the previously used Wilson fermions. The construction reduces…

高能物理 - 格点 · 物理学 2011-05-18 David H. Adams

The properties of the spectrum of the overlap Dirac operator and their relation to random matrix theory are studied. In particular, the predictions from chiral random matrix theory in topologically non-trivial gauge field sectors are…

高能物理 - 格点 · 物理学 2015-06-25 Robert G. Edwards , Urs M. Heller , Joe Kiskis , Rajamani Narayanan

In this contribution we revisit simulations of two-color QCD with rooted staggered quarks at finite density, where baryon-number spontaneously breaks and a diquark condensate forms. We thereby pay special attention to simulating outside the…

高能物理 - 格点 · 物理学 2017-01-18 Lukas Holicki , Jonas Wilhelm , Dominik Smith , Björn Wellegehausen , Lorenz von Smekal

We compare the eigenvalue spectra of the Dirac operator from a simulation with two mass degenerate dynamical chirally improved fermions with Random Matrix Theory. Comparisons with distribution of k-th eigenvalues (k=1,2) in fixed…

高能物理 - 格点 · 物理学 2008-11-26 C. B. Lang , Pushan Majumdar , Wolfgang Ortner

The supersymmetric method is a powerful method for the evaluation of quenched averages in disordered systems. Among others, this method has been applied to the theory of S-matrix fluctuations, the theory of universal conductance…

高能物理 - 理论 · 物理学 2009-11-10 J. J. M. Verbaarschot

Even highly improved variants of lattice QCD with staggered fermions show significant violations of taste symmetry at currently accessible lattice spacings. In addition, the "rooting trick" is used in order to simulate with the correct…

高能物理 - 格点 · 物理学 2008-11-26 Claude Bernard , Maarten Golterman , Yigal Shamir

We perform a comparative study of the infrared properties of overlap and staggered fermions in QCD. We observe that the infrared spectrum of the APE/HYP improved staggered Dirac operator develops a four-fold near-degeneracy and is in…

高能物理 - 格点 · 物理学 2009-11-10 S. Dürr , Ch. Hoelbling , U. Wenger

We derive an index theorem for the Dirac operator in the background of various topological excitations on an R^3 \times S^1 geometry. The index theorem provides more refined data than the APS index for an instanton on R^4 and reproduces it…

高能物理 - 理论 · 物理学 2010-12-09 Erich Poppitz , Mithat Unsal

We extend our lagrangian technique for chiral perturbation theory for quenched QCD to include theories in which only some of the quarks are quenched. We discuss the relationship between the partially quenched theory and a theory in which…

高能物理 - 格点 · 物理学 2016-08-31 Claude Bernard , Maarten Golterman

In this chapter of the Oxford Handbook of Random Matrix Theory we introduce chiral Random Matrix Theories with the global symmetries of QCD. In the microscopic domain, these theories reproduce the mass and chemical potential dependence of…

高能物理 - 理论 · 物理学 2009-10-22 J. J. M. Verbaarschot

We investigate the eigenvalue spectrum of the staggered Dirac matrix in full QCD with two colors and finite chemical potential. Along the strong-coupling axis up to the temperature phase transition, the low-lying Dirac spectrum is well…

高能物理 - 格点 · 物理学 2007-05-23 Elmar Bittner , Maria-Paola Lombardo , Harald Markum , Rainer Pullirsch

In this lecture we argue that the fluctuations of Dirac eigenvalues on the finest scale, i.e. on the scale of the average level spacing do not depend on the underlying dynamics and can be obtained from a chiral random matrix theory with the…

高能物理 - 格点 · 物理学 2007-05-23 J. J. M. Verbaarschot