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We match continuum and lattice heavy-light four-fermion operators at one loop in perturbation theory. For the heavy quarks we use nonrelativistic QCD and for the massless light quarks the highly improved staggered quark action. We include…

High Energy Physics - Lattice · Physics 2014-10-02 Christopher Monahan , Elvira Gamiz , Ron Horgan , Junko Shigemitsu

We investigate the spectrum of the staggered Dirac operator in 4d quenched U(1) lattice gauge theory and its relationship to random matrix theory. In the confined as well as in the Coulomb phase the nearest-neighbor spacing distribution of…

High Energy Physics - Lattice · Physics 2015-06-25 Bernd A. Berg , Harald Markum , Rainer Pullirsch , Tilo Wettig

We have investigated QCD with two flavors of degenerate fermions using a Symanzik-improved lattice action for both the gauge and fermion actions. Our study focuses on the deconfinement transition on an $N_t=4$ lattice. Having located the…

Parafermions are emergent excitations which generalize Majorana fermions and are potentially relevant to topological quantum computation. Using the concept of Fock parafermions, we present a mapping between lattice $\mathbb{Z}_4$…

Strongly Correlated Electrons · Physics 2018-11-21 Alessio Calzona , Tobias Meng , Maura Sassetti , Thomas L. Schmidt

We perform numerical simulations of lattice QCD with two flavors of dynamical overlap quarks, which have exact chiral symmetry on the lattice. While this fermion discretization is computationally demanding, we demonstrate the feasibility to…

We investigate numerically the spectral flow introduced by Adams for the staggered Dirac operator on realistic (quenched) gauge configurations. We obtain clear numerical evidence that the definition works as expected: there is a clear…

High Energy Physics - Lattice · Physics 2015-06-23 V. Azcoiti , G. Di Carlo , E. Follana , A. Vaquero

We propose a new method for Hybrid Monte Carlo (HMC) simulations with odd numbers of dynamical fermions on the lattice. It employs a different approach from polynomial or rational HMC. In this method, gamma-five hermiticity of the lattice…

High Energy Physics - Lattice · Physics 2015-05-27 Kenji Ogawa

We study discretization effects of the Wilson and staggered Dirac operator with $N_{\rm c}>2$ using chiral random matrix theory (chRMT). We obtain analytical results for the joint probability density of Wilson-chRMT in terms of a…

High Energy Physics - Lattice · Physics 2012-02-09 Mario Kieburg , Jacobus J. M. Verbaarschot , Savvas Zafeiropoulos

The low-lying spectrum of the Dirac operator is predicted to be universal, within three classes, depending on symmetry properties specified according to random matrix theory. The three universal classes are the orthogonal, unitary and…

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

We propose a new strategy to evaluate the partition function of lattice QCD with Wilson gauge action coupled to staggered fermions, based on a strong coupling expansion in the inverse bare gauge coupling $\beta= 2N/g^{2}$. Our method makes…

High Energy Physics - Lattice · Physics 2020-02-19 Giuseppe Gagliardi , Wolfgang Unger

We study lattice QCD at non-vanishing chemical potential using the complex Langevin equation. We compare the results with multi-parameter reweighting both from $\mu=0$ and phase quenched ensembles. We find a good agreement for lattice…

High Energy Physics - Lattice · Physics 2015-12-02 Z. Fodor , S. D. Katz , D. Sexty , C. Török

As a part of the project studying large $N_f$ QCD, the LatKMI Collaboration has been investigating the SU(3) gauge theory with four fundamental fermions (four-flavor QCD). The main purpose of studying four-flavor QCD is to provide a…

We provide first evidence that Matrix Models describe the low lying complex Dirac eigenvalues in a theory with dynamical fermions at non-zero density. Lattice data for gauge group SU(2) with staggered fermions are compared to detailed…

High Energy Physics - Lattice · Physics 2007-05-23 Gernot Akemann , Elmar Bittner

We consider the theory of four-fermion interactions with N-component fermions in de Sitter space. It is found that the effective potential for a composite operator in the theory is calculable in the leading order of the 1/N expansion. The…

High Energy Physics - Theory · Physics 2010-01-06 T. Inagaki , S. Mukaigawa , T. Muta

We present a parameter-free Wilson-type lattice Dirac operator with an 81-point stencil for the covariant derivative and the Laplacian which attempts to minimize the breaking of rotational symmetry near the boundary of the Brillouin zone.…

High Energy Physics - Lattice · Physics 2012-06-22 Stephan Durr , Giannis Koutsou

We consider properties of zero and near-zero modes for overlap fermion operator in SU(2) lattice gluodynamics. The density of the states is of the order of Lambda(QCD) while the localization volume of the modes tends to zero in physical…

High Energy Physics - Lattice · Physics 2007-05-23 M. I. Polikarpov , F. V. Gubarev , S. M. Morozov , V. I. Zakharov

We investigate numerically the effect of regulating fermions in the presence of singular background fields in three dimensions. For this, we couple free lattice fermions to a background compact U(1) gauge field consisting of a…

High Energy Physics - Lattice · Physics 2019-11-20 Nikhil Karthik , Rajamani Narayanan

Capitalizing on recent advances in lattice QCD, we present a calculation of the leptonic decay constants f_{B_s} and f_{D_s} that includes effects of one strange sea quark and two light sea quarks. The discretization errors of improved…

High Energy Physics - Phenomenology · Physics 2011-01-27 Matthew Wingate , Christine T. H. Davies , Alan Gray , G. Peter Lepage , Junko Shigemitsu

The inclusion of physical effects from sea quarks has been one of the main advances in lattice QCD simulations over the last few years. We report on recent studies with four flavours of dynamical quarks and address some of the potential…

High Energy Physics - Lattice · Physics 2011-03-09 Gregorio Herdoiza

We formulate a model of relativistic fermions moving in two Euclidean dimensions based on a tight-binding model of graphene. The eigenvalue spectrum of the resulting Dirac operator is solved numerically in smooth U(1) gauge field…

High Energy Physics - Lattice · Physics 2010-04-15 Dipankar Chakrabarti , Simon Hands , Antonio Rago