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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,…

High Energy Physics - Theory · Physics 2009-10-31 Robert G. Edwards , Urs M. Heller , Joe Kiskis , Rajamani Narayanan

We study the low-energy theorems of QCD from the point of view of the dual AdS/QCD models and demonstrate that these models are compatible with the theorems in the chiral limit, i.e. the arising expressions have the same analytical behavior…

High Energy Physics - Phenomenology · Physics 2009-12-10 P. N. Kopnin

In-medium chiral symmetry breaking in confining potential models of QCD is examined. Past attempts to analyse these models have been hampered by infrared divergences that appear at non-zero temperature. We argue that previous attempts to…

High Energy Physics - Phenomenology · Physics 2010-04-06 Pok Man Lo , Eric S. Swanson

The chiral symmetry of QCD is studied at finite temperature and chemical potential using the Schwinger-Dyson equation in the improved ladder approximation. We calculate three order parameters; the vacuum expectation value of the quark…

High Energy Physics - Phenomenology · Physics 2009-10-28 Yusuke Taniguchi , Yuhsuke Yoshida

We study quenched QCD at finite chemical potential, $\mu_I$, for the third component of isospin and quenched two-colour QCD at finite chemical potential, $\mu$, for quark number. In contrast to the quenched approximation to QCD at finite…

High Energy Physics - Lattice · Physics 2009-11-07 J. B. Kogut , D. K. Sinclair

The aim of this work is to shed light on some lesser known aspects of Polyakov-loop--extended chiral models (namely the Polyakov-loop extended Nambu--Jona-Lasinio and Quark-Meson models), especially on the correlation of the quark sector…

High Energy Physics - Phenomenology · Physics 2020-05-06 Hubert Hansen , Rainer Stiele , Pedro Costa

We consider chiral symmetry breaking AdS / QCD models with cubic and quartic potentials in the scalar sector and a z dependent mass for scalars in the bulk. In these models it is possible to get good mesonic spectra using current quark…

High Energy Physics - Phenomenology · Physics 2011-08-08 Alfredo Vega , Ivan Schmidt

We investigate and clarify the role of topology and the issues surrounding the epsilon regime for staggered quarks. We study unimproved and improved staggered quark Dirac operators on quenched lattice QCD gluon backgrounds generated using a…

High Energy Physics - Lattice · Physics 2009-11-11 E. Follana , A. Hart , C. T. H. Davies , Q. Mason

In lattice QCD formalism, we derive an analytical gauge-invariant relation between the Polyakov loop $\langle L_P \rangle$ and the Dirac eigenvalues $\lambda_n$ in QCD, i.e., $\langle L_P \rangle \propto \sum_n \lambda_n^{N_t -1} \langle…

High Energy Physics - Lattice · Physics 2014-03-18 Hideo Suganuma , Takahiro M. Doi , Takumi Iritani

We compute the QCD phase diagram in the plane of the chiral chemical potential and temperature using the linear sigma model coupled to quarks and to the Polyakov loop. The chiral chemical potential accounts for effects of imbalanced…

High Energy Physics - Phenomenology · Physics 2015-03-18 M. N. Chernodub , A. S. Nedelin

We use the graded eigenvalue method, a variant of the supersymmetry technique, to compute the universal spectral correlations of the QCD Dirac operator in the presence of massive dynamical quarks. The calculation is done for the chiral…

High Energy Physics - Theory · Physics 2009-10-31 Burkhard Seif , Tilo Wettig , Thomas Guhr

We construct an effective model for the QCD equation of state, taking into account chiral symmetry restoration as well as the deconfinement phase transition. The correct asymptotic degrees of freedom at the high and low temperature limits…

High Energy Physics - Phenomenology · Physics 2009-09-25 J. Steinheimer , S. Schramm , H. Stöcker

We introduce a random matrix model with the symmetries of QCD at finite temperature and chemical potentials for baryon number and isospin. We analyze the phase diagram of this model in the chemical potential plane for different temperatures…

High Energy Physics - Phenomenology · Physics 2009-11-10 B. Klein , D. Toublan , J. J. M. Verbaarschot

We incorporate chiral symmetry breaking in a soft-wall version of the AdS/QCD model by using a modified dilaton profile and a quartic term in the bulk scalar potential. This allows one to separate the dependence on spontaneous and explicit…

High Energy Physics - Phenomenology · Physics 2015-05-13 Joseph I. Kapusta , Thomas M. Kelley , Tony Gherghetta

We present a quantitative analysis of chiral symmetry breaking in two-flavour continuum QCD in the quenched limit. The theory is set-up at perturbative momenta, where asymptotic freedom leads to precise results. The evolution of QCD towards…

High Energy Physics - Phenomenology · Physics 2015-04-01 Mario Mitter , Jan M. Pawlowski , Nils Strodthoff

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

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 link the spontaneous breakdown of chiral symmetry in Euclidean QCD to the collision of spectral shock waves in the vicinity of zero eigenvalue of Dirac operator. The mechanism, originating from complex Burger's-like equation for viscid,…

High Energy Physics - Phenomenology · Physics 2015-12-23 Jean-Paul Blaizot , Maciej A. Nowak , Piotr Warchoł

We discuss the sign problem in QCD at nonzero chemical potential and its relation with chiral symmetry breaking and the spectrum of the Dirac operator using the framework of chiral random matrix theory. We show that the Banks-Casher formula…

High Energy Physics - Theory · Physics 2009-01-06 K. Splittorff , J. J. M. Verbaarschot

We perform a lattice investigation of QCD with three colors and 2 flavors of Dirac (staggered) fermions in the adjoint representation, defined on a 4d space with one spatial dimension compactified, and study the phase structure of the…

High Energy Physics - Lattice · Physics 2009-07-22 Guido Cossu , Massimo D'Elia