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We calculate the electromagnetic pion form factor at intermediate space-like momentum transfer from the QCD sum rule for the correlation function of two {\it pseudoscalar } interpolating fields and the electromagnetic current. This…

High Energy Physics - Phenomenology · Physics 2009-10-28 Hilmar Forkel , Marina Nielsen

A variety of evidence from lattice QCD is presented revealing the dominant role of instantons in the propagation of light quarks in the QCD vacuum and in light hadron structure. The instanton content of lattice gluon configurations is…

High Energy Physics - Lattice · Physics 2009-10-30 J. W. Negele

We revisit the hard QCD contributions to the pion gravitational form factors (GFFs), in terms of the twist-2,3 pion distribution amplitudes (DA), including novel semi-hard contributions from the instantons. The pion DAs are evaluated in the…

High Energy Physics - Phenomenology · Physics 2024-10-16 Wei-Yang Liu , Edward Shuryak , Ismail Zahed

Nonperturbative nolocal structure of QCD vacuum is well described by instanton model. Specific helicity and flavor structure of zero modes of quarks in instanton field allows simultaneously to explain some important features of low- and…

High Energy Physics - Phenomenology · Physics 2009-11-07 A. E. Dorokhov

We study the effects of instantons on the charged pion electro-magnetic formfactor at intermediate momenta. In the Single Instanton Approximation (SIA), we predict the pion formfactor in the kinematic region Q^2=2-15 GeV^2. By developing…

High Energy Physics - Phenomenology · Physics 2009-11-07 P. Faccioli , A. Schwenk , E. V. Shuryak

An elementary introduction is presented to the study of hadron structure using lattice QCD. Following a brief review of relevant aspects of path integrals, the discrete lattice path integral is presented for gluon and quark fields and used…

High Energy Physics - Lattice · Physics 2007-05-23 J. W. Negele

The Interacting Instanton Liquid Model is used to explore the role of instanton induced dynamics in hadron structure. To support the validity of this model in the chiral regime, the quark mass dependencies of several properties are shown to…

High Energy Physics - Phenomenology · Physics 2008-11-26 M. Cristoforetti , P. Faccioli , M. C. Traini , J. W. Negele

Gluon two- and three-point Green Functions computed in Landau gauge from the lattice show the existence of power corrections to the purely perturbative expressions, that can be explained through an Operator Product Expansion as the…

High Energy Physics - Phenomenology · Physics 2016-08-16 Ph. Boucaud , F. De Soto , A. Donini , J. P. Leroy , A. Le Yaouanc , J. Micheli , H. Moutarde , O. Pène , J. Rodríguez-Quintero

We propose an effective lagrangian for the coupling of the neutral pion with gluons whose strength is determined by a low energy theorem. We calculate the contribution of the gluonic components arising from this interaction to the pion…

High Energy Physics - Phenomenology · Physics 2010-05-28 N. I. Kochelev , V. Vento

Quantum Chromodynamics (QCD) exhibits complementary descriptions of hadrons: a rest-frame picture based on confinement, chiral symmetry breaking and interquark forces, and a high-energy light-front picture expressed through parton…

High Energy Physics - Phenomenology · Physics 2026-01-22 Edward Shuryak , Ismail Zahed

In this presentation, we briefly review recent investigations on pion and kaon structures from the instanton vacuum. Starting from the low-energy QCD partition function, we have computed the Gasser-Leutwyler low-energy constants,…

High Energy Physics - Phenomenology · Physics 2015-05-13 Hyun-Chul Kim , Seung-il Nam , Hyun-Ah Choi

Pion transition form factor for the process $\gamma*\gamma*\to \pi^0$ at space-like values of photon momenta is calculated within the effective quark-meson model with the interaction induced by instanton exchange. The leading and…

High Energy Physics - Phenomenology · Physics 2014-11-17 A. E. Dorokhov

This review contains an overview over recent results for the electromagnetic iso-vector form factor of the pion obtained in lattice QCD with dynamical fermions. Particular attention is given to the extrapolation to the physical point and an…

High Energy Physics - Lattice · Physics 2014-02-14 Bastian B. Brandt

We develop a relativistic quark model for pion structure, which incorporates the non-trivial structure of the vacuum of Quantum Chromodynamics as modelled by instantons. Pions are boundstates of quarks and the strong quark-pion vertex is…

High Energy Physics - Phenomenology · Physics 2009-10-31 I. V. Anikin , A. E. Dorokhov , A. E. Maximov , L. Tomio , V. Vento

In this review we will concentrate on the nonperturbative effects in the properties of hadrons made from the light-heavy and heavy-heavy quarks in the framework of Instanton Liquid Model (ILM) of QCD vacuum. We briefly discuss the main…

High Energy Physics - Phenomenology · Physics 2022-01-26 M. Musakhanov , U. Yakhshiev

To elucidate the role in hadron structure of quark zero modes associated with instantons, the lowest eigenfunctions of the Dirac operator have been calculated in quenched QCD, full QCD, and full QCD with cooling. Eigenmodes associated with…

High Energy Physics - Lattice · Physics 2009-09-25 T. L. Ivanenko , J. W. Negele

We study the role of semi-classical QCD vacuum solutions in high energy scattering by considering the instanton contribution to hadronic cross sections. We propose a new type of instanton-induced interactions (``instanton ladder'') that…

High Energy Physics - Phenomenology · Physics 2009-10-31 Dmitri E. Kharzeev , Yuri V. Kovchegov , Eugene Levin

In recent years, significant progress was reached in understanding of vacuum and hadronic structure. We review recent works on the {\it point-to-point correlation functions}, comparing those obtained from phenomenology, ``instanton liquid"…

High Energy Physics - Phenomenology · Physics 2016-11-03 Edward Shuryak

The influence of nonperturbative fields on instantons in quantum chromodynamics is studied. Nonperturbative vacuum is described in terms of nonlocal gauge invariant vacuum averages of gluon field strength.Effective action for instanton is…

High Energy Physics - Phenomenology · Physics 2015-06-25 Nikita O. Agasian , Sergei M. Fedorov

We present an analysis of QCD sum rules for pion form factor in next-to-leading order of perturbation theory for the case of pseudoscalar pion currents. The essential instanton contribution is reanalysed with account for present more…

High Energy Physics - Phenomenology · Physics 2009-11-10 V. V. Braguta , A. I. Onishchenko