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The coupling of spin 0 and spin 1 external fields to Dirac fermions defines a theory which displays gauge chiral symmetry. Quantum mechanically, functional integration of the fermions yields the determinant of the Dirac operator, known as…

High Energy Physics - Theory · Physics 2008-12-18 L. L. Salcedo

We investigate the axial $U(1)$ symmetry restoration at finite temperature in two flavor QCD. We employ the M\"obius domain-wall formalism that is designed to achieve good chiral symmetry. We show the measurements of a difference of meson…

High Energy Physics - Lattice · Physics 2014-12-19 JLQCD Collaboration , Guido Cossu , Hidenori Fukaya , Shoji Hashimoto , Takashi Kaneko , Jun-ichi Noaki , Akio Tomiya

We compare the behavior of different lattice Dirac operators in gauge backgrounds which are lattice discretizations of a classical instanton. In particular we analyze the standard Wilson operator, a chirally improved Dirac operator and the…

High Energy Physics - Lattice · Physics 2008-11-26 Christof Gattringer , Meinulf Göckeler , C. B. Lang , P. E. L. Rakow , Andreas Schäfer

We present non-perturbative results for the constants needed for on-shell $O(a)$ improvement of bilinear operators composed of Wilson fermions. We work at $\beta=6.0$ and 6.2 in the quenched approximation. The calculation is done by…

High Energy Physics - Lattice · Physics 2007-05-23 Tanmoy Bhattacharya , Rajan Gupta , Weonjong Lee , Stephen Sharpe

For Wilson and clover fermions traditional formulations of the axial vector current do not respect the continuum Ward identity which relates the divergence of that current to the pseudoscalar density. Here we propose to use a point-split or…

High Energy Physics - Lattice · Physics 2015-11-18 R. Horsley , Y. Nakamura , H. Perlt , P. E. L. Rakow , G. Schierholz , A. Schiller , J. M. Zanotti

By using Symanzik's improvement program, we study on-shell improved lattice QCD with staggered fermions. We find that there are as many as 15 independent lattice operators of dimension of six~(including both gauge and fermion operators)…

High Energy Physics - Lattice · Physics 2009-10-30 Yubing Luo

We analyze the eigenvalues and eigenvectors of the staggered Dirac operator in quenched lattice QCD in the vicinity of the deconfinement phase transition using the L\"uscher-Weisz gauge action. The spectral and localization properties of…

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

The Chern number, nu, as a topological invariant that identifies the winding of the ground state in the particle-hole space, is a definitive theoretical signature that determines whether a given superconducting system can support Majorana…

Superconductivity · Physics 2013-07-16 Jiannis K. Pachos , Emilio Alba , Ville Lahtinen , Juan J. Garcia-Ripoll

We study the low-lying eigenmodes of the lattice overlap Dirac operator for SU(N) gauge theories with N=2,3,4 and 5 colours. We define a fermionic topological charge from the zero-modes of this operator and show that, as N grows, any…

High Energy Physics - Lattice · Physics 2009-11-07 Nigel Cundy , Michael Teper , Urs Wenger

It is possible to improve the chiral behaviour and the approach to the continuum limit of correlation functions in lattice QCD with standard and twisted Wilson fermions by taking arithmetic averages of correlators computed in theories…

High Energy Physics - Lattice · Physics 2009-11-10 R. Frezzotti , G. C. Rossi

We study zero modes of Laplacians on compact and non-compact metric graphs with general self-adjoint vertex conditions. In the first part of the paper the number of zero modes is expressed in terms of the trace of a unitary matrix…

Mathematical Physics · Physics 2015-05-27 Jens Bolte , Sebastian Egger , Frank Steiner

The phase diagram for staggered fermions is discussed in the context of the staggered chiral Lagrangian, extending previous work on the subject. When the discretization errors are significant, there may be an Aoki-like phase for staggered…

High Energy Physics - Lattice · Physics 2009-11-10 C. Aubin , Qinghai Wang

A novel algorithm for real-time modal identification in linear vibrating systems with complex modes is introduced, utilizing a combination of first order eigen-perturbation and second order separation techniques. In practical settings,…

Systems and Control · Electrical Eng. & Systems 2023-04-27 Satyam Panda , Sanghamitra Das , Basuraj Bhowmik , Budhaditya Hazra

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

We investigate chiral properties of the domain-wall fermion (DWF) system. After a brief introduction for the DWF, we summarize the recent numerical results on the chiral properties of the domain-wall QCD (DWQCD), which seem mutually…

High Energy Physics - Lattice · Physics 2009-11-07 Sinya Aoki

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 discuss fermionic zero modes in the two-dimensional chiral p-wave superconductors. We show quite generally, that without fine-tuning, in a macroscopic sample there is only one or zero of such Majorana-fermion modes depending only on…

Superconductivity · Physics 2007-07-03 V. Gurarie , L. Radzihovsky

We consider $4d$ compact lattice QED in the quenched approximation. First, we briefly summarize the spectrum of the staggered Dirac operator and its connection with random matrix theory. Afterwards we present results for the low-lying…

High Energy Physics - Lattice · Physics 2008-11-26 Bernd A. Berg , Urs M. Heller , Harald Markum , Rainer Pullirsch , Wolfgang Sakuler

We compute the chiral condensate in 2+1-flavor QCD through the spectrum of low-lying eigenmodes of Dirac operator. The number of eigenvalues of the Dirac operator is evaluated using a stochastic method with an eigenvalue filtering technique…

High Energy Physics - Lattice · Physics 2016-08-22 Guido Cossu , Hidenori Fukaya , Shoji Hashimoto , Takashi Kaneko , Jun-Ichi Noaki

We propose a lattice action including unphysical Wilson fermions with a negative mass m_0 of the order of the inverse lattice spacing. With this action, the exact zero mode of the hermitian Wilson-Dirac operator H_W(m_0) cannot appear and…

High Energy Physics - Lattice · Physics 2009-11-11 JLQCD collaboration , H. Fukaya , S. Hashimoto , K. -I. Ishikawa , T. Kaneko , H. Matsufuru , T. Onogi , N. Yamada