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We study the spectrum of the QCD Dirac operator near zero virtuality for $N_c =2$. According to a universality argument, it can be described by a random matrix theory with the chiral structure of QCD, but with $real$ matrix elements. Using…

High Energy Physics - Theory · Physics 2009-10-28 Jacobus Verbaarschot

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 report tests and results from a new approach to the spectral density and the mode number distribution of the Dirac operator in lattice gauge theories. The algorithm generates the spectral density of the lattice Dirac operator as a…

High Energy Physics - Lattice · Physics 2016-05-27 Zoltan Fodor , Kieran Holland , Julius Kuti , Santanu Mondal , Daniel Nogradi , Chik Him Wong

In this paper, we study the spectrality of the non-self-adjoint Dirac operator L(Q) with a complex-valued periodic matrix potential Q. We establish a condition on the off-diagonal elements of the matrix Q under which L(Q) is an…

Spectral Theory · Mathematics 2026-03-04 O. A. Veliev

We present a method for the numerical calculation of derivatives of functions of general complex matrices. The method can be used in combination with any algorithm that evaluates or approximates the desired matrix function, in particular…

High Energy Physics - Lattice · Physics 2016-10-13 M. Puhr , P. V. Buividovich

We compute by Monte Carlo methods the individual distributions of the $k$th smallest Dirac operator eigenvalues in QCD, and compare them with recent analytical predictions. We do this for both massless and massive quarks in an SU(3) gauge…

High Energy Physics - Lattice · Physics 2009-10-31 P. H. Damgaard , U. M. Heller , R. Niclasen , K. Rummukainen

Random Matrix Theory has been a unifying approach in physics and mathematics.In these lectures we discuss applications of Random Matrix Theory to QCD and emphasize underlying integrable structures. In the first lecture we give an overview…

High Energy Physics - Theory · Physics 2007-05-23 J. J. M. Verbaarschot

We study the spectrum of the hermitian Wilson Dirac operator in the epsilon-regime of QCD in the quenched approximation and compare it to predictions from Wilson Random Matrix Theory. Using the distributions of single eigenvalues in the…

High Energy Physics - Lattice · Physics 2011-12-22 Albert Deuzeman , Urs Wenger , Jaïr Wuilloud

We derive bounds on the location of non-embedded eigenvalues of Dirac operators on the half-line with non-Hermitian $L^1$-potentials. The results are sharp in the non-relativistic or weak-coupling limit. In the massless case, the absence of…

Spectral Theory · Mathematics 2013-11-27 Jean-Claude Cuenin

We study some interesting aspects of the spectral properties of SU(3) gauge theory, both with and without dynamical quarks (QCD) at thermal equilibrium using lattice gauge theory techniques. By calculating the eigenstates of a massless…

High Energy Physics - Lattice · Physics 2026-03-05 Harshit Pandey , Ravi Shanker , Sayantan Sharma

We formulate a random matrix model which mimics the chiral phase transition in QCD with two light flavors. Two critical exponents are calculated. We obtain the mean field values $\beta = \frac 12 $ and $\delta = 3$. We also find that the…

High Energy Physics - Phenomenology · Physics 2009-10-28 A. D. Jackson , J. J. M. Verbaarschot

The low energy eigenmodes of the continuum QCD Dirac operator are extended, but on the lattice, due to discretization effects, the Dirac operator can have localized eigenmodes. These non-physical modes can introduce strong lattice artifacts…

High Energy Physics - Lattice · Physics 2009-04-14 Anna Hasenfratz , Roland Hoffmann , Stefan Schaefer

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

We study lattice QCD in the limit that the quark mass and chemical potential are simultaneously made large, resulting in a controllable density of quarks which do not move; this is similar in spirit to the quenched approximation for zero…

High Energy Physics - Lattice · Physics 2007-05-23 T. Blum , J. E. Hetrick , D. Toussaint

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

Some exact relations for the spectral density $\rho(\lambda)$ of the Euclidean Dirac operator in $QCD$ are derived. They follow directly from the chiral symmetry of the $QCD$ lagrangian with massless quarks. New results are obtained both in…

High Energy Physics - Theory · Physics 2008-02-03 A. Smilga

Large ensembles of complete spectra of the Euclidean Dirac operator for staggered fermions are calculated for SU(2) lattice gauge theory. The accumulation of eigenvalues near zero is analyzed as a signal of chiral symmetry breaking and…

High Energy Physics - Lattice · Physics 2009-10-30 M. E. Berbenni-Bitsch , S. Meyer , A. Schäfer , J. J. M. Verbaarschot , T. Wettig

The spontaneous breaking of chiral symmetry in QCD is known to be linked to a non-zero density of eigenvalues of the massless Dirac operator near the origin. Numerical studies of two-flavour QCD now suggest that the low quark modes are…

High Energy Physics - Lattice · Physics 2008-11-26 Martin Lüscher

We study characteristic features of the eigenvalues of the Wilson-Dirac operator in topologically non-trivial gauge field configurations by examining complete spectra of the fermion matrix. In particular we discuss the role of eigenvectors…

High Energy Physics - Lattice · Physics 2009-10-30 Christof Gattringer , Ivan Hip

We introduce novel relations between the derivatives [$\partial^{n}\rho(\lambda, m_{l})/\partial m_{l}^n$] of the Dirac eigenvalue spectrum [$\rho(\lambda, m_{l})$] with respect to the light sea quark mass ($m_{l}$) and the $(n+1)$-point…

High Energy Physics - Lattice · Physics 2021-02-25 H. -T. Ding , S. -T. Li , Swagato Mukherjee , A. Tomiya , X. -D. Wang , Y. Zhang