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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 use a chiral random matrix model to investigate the effects of massive quarks on the distribution of eigenvalues of QCD inspired Dirac operators. Kalkreuter's lattice analysis of the spectrum of the massive (hermitean) Dirac operator for…

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

It has recently been found that dynamics of pure glue QCD supports the low energy band of Dirac modes with local chiral properties qualitatively different from that of a bulk: while bulk modes suppress chirality relative to statistical…

High Energy Physics - Lattice · Physics 2015-06-12 Andrei Alexandru , Ivan Horvath

We investigate the contribution that instantons make to the QCD chiral condensate for Nf= 0, 1 and 2 quark flavours. We use a simplified model: the instantons are a (weighted) gas, the fermionic integrations are restricted to the subspace…

High Energy Physics - Phenomenology · Physics 2007-05-23 U. Sharan , M. Teper

It is known that contrary to expectations, the order parameter of chiral symmetry breaking, the Dirac spectral density at zero virtuality does not vanish above the critical temperature of QCD. Instead, the spectral density develops a…

High Energy Physics - Lattice · Physics 2022-12-13 Tamas G. Kovacs

We present a hydrodynamical description of the QCD Dirac spectrum at finite chemical potential as an uncompressible droplet in the complex eigenvalue space. For a large droplet, the fluctuation spectrum around the hydrostatic solution is…

High Energy Physics - Phenomenology · Physics 2015-12-23 Yizhuang Liu , Piotr Warchol , Ismail Zahed

Starting from the chiral Lagrangian for Wilson fermions at nonzero lattice spacing we have obtained compact expressions for all spectral correlation functions of the Hermitian Wilson Dirac operator in the $\epsilon$-domain of QCD with…

High Energy Physics - Lattice · Physics 2011-12-05 K. Splittorff , J. J. M. Verbaarschot

We reveal that the criticality of the chiral phase transition in QCD at the macroscale arises from the microscopic energy levels of its fundamental constituents, the quarks. We establish a novel relation between cumulants of the chiral…

High Energy Physics - Lattice · Physics 2024-02-28 Heng-Tong Ding , Wei-Ping Huang , Swagato Mukherjee , Peter Petreczky

We study the spectrum of the QCD Dirac operator for two colors with fermions in the fundamental representation and for two or more colors with adjoint fermions. For $N_f$ flavors, the chiral flavor symmetry of these theories is…

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

We analyze the statistical properties of the spectrum of the QCD Dirac operator at low energy in a finite box of volume $L^4$ by means of partially quenched Chiral Perturbation Theory (pqChPT), a low-energy effective field theory based on…

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

We apply the probability distribution function method to the study of chiral properties of QCD with quarks in the exact massless limit. A relation among the chiral condensate, zeros of the Bessel function and eigenvalue of Dirac operator is…

High Energy Physics - Lattice · Physics 2009-10-02 Xiang-Qian Luo

We study physics at temperatures just above the QCD phase transition (Tc) using chiral (overlap) Fermions in the quenched approximation of lattice QCD. Exact zero modes of the overlap Dirac operator are localized and their frequency of…

High Energy Physics - Lattice · Physics 2011-07-19 Rajiv V. Gavai , Sourendu Gupta , R. Lacaze

We reveal that the universal scaling properties of the chiral phase transition in quantum chromodynamics (QCD) at the macroscale are, in fact, encoded within the microscopic energy levels of its fundamental constituents, the quarks. We…

High Energy Physics - Lattice · Physics 2024-01-22 Heng-Tong Ding , Wei-Ping Huang , Swagato Mukherjee , Peter Petreczky

We compute the spectral density of the (Hermitean) Dirac operator in Quantum Chromodynamics with two light degenerate quarks near the origin. We use CLS/ALPHA lattices generated with two flavours of O(a)-improved Wilson fermions…

High Energy Physics - Lattice · Physics 2015-03-25 Georg P. Engel , Leonardo Giusti , Stefano Lottini , Rainer Sommer

The order parameter of the chiral phase transition is directly related to the infrared part of the spectrum of the QCD Dirac operator. This part of the spectrum follows from the low energy limit of QCD which is given by a partition function…

High Energy Physics - Phenomenology · Physics 2009-10-31 J. J. M. Verbaarschot

The importance of the spectral density of the Dirac operator in studying spontaneous chiral symmetry breaking and anomalous U(1) axial symmetry breaking are reviewed. It is shown that both types of symmetry breaking can be traced to effects…

Nuclear Theory · Physics 2007-05-23 Thomas D. Cohen

We compare eigenvalue correlations of the Dirac operator with a chemical potential obtained from lattice simulations of quenched QCD with analytic predictions obtained from chiral effective theories in the zero-momentum limit. By comparing…

High Energy Physics - Lattice · Physics 2008-11-26 James C. Osborn , Tilo Wettig

We investigate the eigenvalue spectrum of the staggered Dirac matrix in two-color QCD at nonzero temperature and at baryon density when the eigenvalues become complex. The quasi-zero modes and their role for chiral symmetry breaking and the…

High Energy Physics - Phenomenology · Physics 2007-05-23 Elmar Bittner , Maria-Paola Lombardo , Harald Markum , Rainer Pullirsch

We study the distribution of the phase angle and the magnitude of the fermion determinant as well as its correlation with the chiral condensate and the baryon number for QCD at non-zero quark chemical potential. Results are derived to…

High Energy Physics - Lattice · Physics 2010-03-19 M. P. Lombardo , K. Splittorff , J. J. M. Verbaarschot

We study the singular values of the Dirac operator in dense QCD-like theories at zero temperature. The Dirac singular values are real and nonnegative at any nonzero quark density. The scale of their spectrum is set by the diquark…

High Energy Physics - Phenomenology · Physics 2011-12-15 Takuya Kanazawa , Tilo Wettig , Naoki Yamamoto