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When chiral symmetry is spontaneously broken, the low-energy part of the Dirac operator spectrum can be computed analytically in the chiral limit. The tool is effective field theory or, equivalently in this case, Random Matrix Theory.

High Energy Physics - Phenomenology · Physics 2007-05-23 P. H. Damgaard

We study the spectrum of the QCD Dirac operator by means of the valence quark mass dependence of the chiral condensate in partially quenched Chiral Perturbation Theory (pqChPT) in the supersymmetric formulation of Bernard and Golterman. We…

High Energy Physics - Theory · Physics 2009-10-31 J. C. Osborn , D. Toublan , J. J. M. Verbaarschot

We compute the ratio $\Lambda_L/\Lambda_{\bar{MS}}$ between the scale parameter $\Lambda_L$, associated with a lattice formulation of QCD using the overlap-Dirac operator, and $\Lambda_{\bar{MS}}$ of the $\bar{\rm MS}$ renormalization…

High Energy Physics - Lattice · Physics 2009-10-31 C. Alexandrou , H. Panagopoulos , E. Vicari

In the dilute instanton gas model of the QCD vacuum, one expects a strong spatial correlation between chirality and the maxima of the Dirac eigenvectors with small eigenvalues. Following Horvath, {\it et al.} we examine this question using…

High Energy Physics - Lattice · Physics 2009-11-07 T. Blum , N. Christ , C. Cristian , C. Dawson , X. Liao , G. Liu , R. Mawhinney , L. Wu , Y. Zhestkov

In this paper we study a random matrix model with the chiral and flavor structure of the QCD Dirac operator and a temperature dependence given by the lowest Matsubara frequency. Using the supersymmetric method for random matrix theory, we…

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

The spectrum of the Dirac operator near zero virtuality obtained in lattice gauge simulations is known to be universally described by chiral random matrix theory. We address the question of the maximum energy for which this universality…

High Energy Physics - Phenomenology · Physics 2009-10-31 M. E. Berbenni-Bitsch , M. Göckeler , T. Guhr , A. D. Jackson , J. -Z. Ma , S. Meyer , A. Schäfer , H. A. Weidenmüller , T. Wettig , T. Wilke

The distribution of the low-lying QCD Dirac spectrum is analyzed by means of partial quenched chiral perturbation theory. We identify an energy scale below which the valence quark mass dependence of the QCD partition function is given by…

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

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

We investigate the eigenvalue spectrum of the staggered Dirac matrix in two color QCD at finite chemical potential. The profiles of complex eigenvalues close to the origin are compared to a complex generalization of the chiral Gaussian…

High Energy Physics - Lattice · Physics 2008-11-26 Gernot Akemann , Elmar Bittner , Maria-Paola Lombardo , Harald Markum , Rainer Pullirsch

A detailed investigation of the low-energy chiral expansion is presented within a model truncation of QCD. The truncation allows for a phenomenological description of the quark-quark interaction in a framework which maintains the global…

Nuclear Theory · Physics 2008-11-26 M. R. Frank , T. Meissner

We use a chiral random matrix model with 2N_f flavors to mock up the QCD Dirac spectrum at finite chemical potential. We show that the 1/N approximation breaks down in the quenched state with spontaneously broken chiral symmetry. The…

High Energy Physics - Phenomenology · Physics 2016-08-15 Romuald A. Janik , Maciej A. Nowak , Gábor Papp , Ismail Zahed

We study the spectrum and eigenmodes of the QCD Dirac operator in a gauge background given by an Instanton Liquid Model (ILM) at temperatures around the chiral phase transition. For two massless quark flavors we observe that at the chiral…

High Energy Physics - Lattice · Physics 2007-05-23 Antonio M. Garcia-Garcia , James C. Osborn

We propose a simple instanton-based random matrix model of hot QCD that in the quenched case precisely reproduces the distribution of the lowest lattice overlap Dirac eigenvalues. Even after including dynamical quarks the model can be…

High Energy Physics - Lattice · Physics 2025-02-04 Tamas G. Kovacs

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

We present a detailed study of the interplay between chiral symmetry and spectral properties of the Dirac operator in lattice gauge theories. We consider, in the framework of the Schwinger model, the fixed point action and a fermion action…

High Energy Physics - Lattice · Physics 2009-10-31 F. Farchioni , I. Hip , C. B. Lang , M. Wohlgenannt

At low temperature the low-lying QCD Dirac spectrum obeys random matrix statistics. Recently we found that above $T_{c}$ the lowest part of the spectrum consists of localized modes that obey Poisson statistics. An interesting implication of…

High Energy Physics - Lattice · Physics 2014-11-03 Matteo Giordano , Sandor D. Katz , Tamas G. Kovacs , Ferenc Pittler

We propose a framework for quantitative evaluation of dynamical tendency for polarization in arbitrary random variable that can be decomposed into a pair of orthogonal subspaces. The method uses measures based on comparisons of given…

High Energy Physics - Lattice · Physics 2011-08-05 Andrei Alexandru , Terrence Draper , Ivan Horvath , Thomas Streuer

We review recent results on the phase structure of QCD and bulk QCD thermodynamics. In particular we discuss how universal critical scaling related to spontaneous breaking of the chiral symmetry manifests itself in recent lattice QCD…

High Energy Physics - Lattice · Physics 2017-10-11 Christian Schmidt , Sayantan Sharma

In this talk, I first motivate the use of Chiral Perturbation Theory in the context of Lattice QCD. In particular, I explain how partially quenched QCD, which has, in general, unequal valence- and sea-quark masses, can be used to obtain…

High Energy Physics - Phenomenology · Physics 2017-08-23 Maarten Golterman

I describe a mechanism to understand the relation between chiral-symmetry breaking and eigenmodes of the Dirac operator in lattice QCD with Kogut-Susskind sea quarks. It can be shown that if chiral symmetry is spontaneously broken, the…

High Energy Physics - Lattice · Physics 2009-10-31 Xiang-Qian Luo