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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

We discuss a novel strategy for computing the eigenvalues and eigenfunctions of the relativistic Dirac operator with a radially symmetric potential. The virtues of this strategy lie on the fact that it avoids completely the phenomenon of…

Analysis of PDEs · Mathematics 2019-02-20 Lyonell Boulton , Nabile Boussaid

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 calculate correlations between hadronic current operators as a function of their spatial separation, in a quenched lattice QCD simulation at $\beta=6.2$ on a $24^3\times48$ lattice. The lattice fermion formulation used is that due to…

High Energy Physics - Lattice · Physics 2007-05-23 UKQCD Collaboration , S. J. Hands , P. W. Stephenson , A. McKerrell

We solve a family of Gaussian two-matrix models with rectangular Nx(N+v) matrices, having real asymmetric matrix elements and depending on a non-Hermiticity parameter mu. Our model can be thought of as the chiral extension of the real…

High Energy Physics - Theory · Physics 2010-05-07 G. Akemann , M. J. Phillips , H. -J. Sommers

We introduce a random two-matrix model interpolating between a chiral Hermitian (2n+nu)x(2n+nu) matrix and a second Hermitian matrix without symmetries. These are taken from the chiral Gaussian Unitary Ensemble (chGUE) and Gaussian Unitary…

Mathematical Physics · Physics 2011-11-03 Gernot Akemann , Taro Nagao

The Thirring model is an interacting fermion theory with current-current interaction. The model in $1+2$ dimensions has applications in condensed-matter physics to describe the electronic excitations of Dirac materials. Earlier…

High Energy Physics - Lattice · Physics 2019-09-11 Julian Lenz , Björn Wellegehausen , Andreas Wipf

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

We present simulation results for lattice QCD with chiral fermions in small volumes, where the epsilon-expansion of chiral perturbation theory applies. Our data for the low lying Dirac eigenvalues, as well as mesonic correlation functions,…

High Energy Physics - Lattice · Physics 2009-11-11 W. Bietenholz , T. Chiarappa , K. Jansen , K. -I. Nagai , S. Shcheredin

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

This thesis is dedicated to explore the feasibility of numerical calculations in the $\epsilon$--regime of QCD for the extraction of physical information. We apply two formulations of the Ginsparg-Wilson fermions the Neuberger operator and…

High Energy Physics - Lattice · Physics 2007-05-23 S. Shcheredin

A distinctive feature of the presence of spontaneous chiral symmetry breaking in QCD is the condensation of low modes of the Dirac operator near the origin. The rate of condensation must be equal to the slope of (Mpi^2 Fpi^2)/2 with respect…

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

We investigate general properties of the eigenvalue spectrum for improved staggered quarks. We introduce a new chirality operator $[\gamma_5 \otimes 1]$ and a new shift operator $[1 \otimes \xi_5]$, which respect the same recursion relation…

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 eigenvalues and eigenvectors of the staggered Dirac operator in the vicinity of the chiral phase transition of quenched SU(3) lattice gauge theory. We consider both the global features of the spectrum and the local…

High Energy Physics - Lattice · Physics 2008-11-26 M. Göckeler , H. Hehl , P. E. L. Rakow , A. Schäfer , W. Söldner , T. Wettig

We use the linear sigma model with quarks to study the QCD phase diagram from the point of view of chiral symmetry restoration. We compute the leading order effective potential for high and low temperatures and finite quark chemical…

High Energy Physics - Phenomenology · Physics 2018-01-31 Alejandro Ayala , Saul Hernandez-Ortiz , Luis A. Hernandez

We study the phase structure of mixed-action QCD with two Wilson sea quarks and two chiral valence quarks, starting from the chiral lagrangian. A priori, the effective theory allows for a rich phase structure, including a phase with a…

High Energy Physics - Lattice · Physics 2011-10-13 Oliver Baer , Maarten Golterman , Yigal Shamir

A chiral fermion action allows one to do very clean studies of chiral symmetry breaking in QCD. I will briefly describe how to compute with the overlap action (relatively) cheaply, and then turn to physics: Low modes of the Dirac operator…

High Energy Physics - Lattice · Physics 2007-05-23 Thomas DeGrand

We investigate the universal features of chiral symmetry breaking in large-$N$ QCD by comparing non-perturbative determinations of the low-lying Dirac spectrum with chiral Random Matrix Theory (RMT) predictions. Our numerical Monte Carlo…

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