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Instantons are the natural mechanism in non-perturbative QCD to remove helicity from valence quarks and transfer it to gluons and quark-antiquark pairs. To understand the extent to which instantons explain the so-called "spin crisis" in the…

High Energy Physics - Lattice · Physics 2008-11-26 D. Dolgov , R. Brower , J. W. Negele , A. Pochinsky

QCD point-to-point correlation functions at distances .2-1 fm are very different for different channels, and they tell us a lot about inter-quark interactions. Recent studies based on experimental data, 'instanton liquid' approach and…

High Energy Physics - Lattice · Physics 2009-10-22 E. Shuryak

We consider the local chirality of near-zero eigenvectors from Wilson-Dirac and clover improved Wilson-Dirac lattice operators as proposed recently by Horv\'ath et al. We studied finer lattices and repaired for the loss of orthogonality due…

High Energy Physics - Lattice · Physics 2009-11-07 I. Hip , Th. Lippert , H. Neff , K. Schilling , W. Schroers

Generalised Parton Distributions (GPDs) provide multidimensional insight into hadron structure and are particularly relevant for the pion, whose dynamics are intimately linked to chiral symmetry breaking. We introduce a novel modelling…

High Energy Physics - Phenomenology · Physics 2026-03-19 J. M. Morgado-Chávez , J. Segovia , F. de Soto , J. Rodríguez-Quintero , V. Bertone , M. Defurne , C. Mezrag , H. Moutarde

We present a lattice QCD calculation of the double-virtual neutral pion transition form factor, with the goal to cover the kinematic range relevant to hadronic light-by-light scattering in the muon $g-2$. Several improvements have been made…

High Energy Physics - Lattice · Physics 2019-09-26 Antoine Gérardin , Harvey B. Meyer , Andreas Nyffeler

We use Wegner's flow equation method to investigate the infinite-$U$ periodic Anderson model. We show that this method poses a new approach to the description of heavy fermion behaviour. Within this scheme we derive an effective Hamiltonian…

Strongly Correlated Electrons · Physics 2009-11-10 Karsten Meyer

Discovery of instantons in colliders will provide experimental evidence for the topological properties of the QCD vacuum. In this work, we propose jet correlation observables that can unambiguously discriminate between instanton-induced…

High Energy Physics - Phenomenology · Physics 2026-04-23 Sayak Guin , Swagatam Tah , Nihar Ranjan Sahoo , Sayantan Sharma

The electromagnetic form factor of the pion is calculated in the "point-form" of relativistic quantum mechanics using simple, phenomenological wave functions. It is found that the squared charge radius of the pion is predicted one order of…

High Energy Physics - Phenomenology · Physics 2015-06-25 A. Amghar , B. Desplanques , L. Theussl

We investigate the leading-twist light-cone distribution amplitudes for the pion and kaon, based on the nonlocal chiral quark model from the instanton vacuum. Effects of explicit flavor SU(3)-symmetry breaking are taken into account. The…

High Energy Physics - Phenomenology · Physics 2009-11-11 Seung-il Nam , Hyun-Chul Kim , Atsushi Hosaka , M. M. Musakhanov

We investigate the structure of the light meson with one dynamical gluon from the light-front QCD Hamiltonian, determined for their constituent quark-antiquark and quark-antiquark-gluon Fock sectors, together with a three-dimensional…

High Energy Physics - Phenomenology · Physics 2022-01-19 Jiangshan Lan , Kaiyu Fu , Chandan Mondal , Xingbo Zhao , James P. Vary

The transition form factor, decay width and charge form factor of pion are calculated within the model of induced nonlocal quark currents based on the assumption that the nonperturbative QCD vacuum can be characterized by a homogeneous…

High Energy Physics - Phenomenology · Physics 2007-05-23 Ja. V. Burdanov , G. V. Efimov , S. N. Nedelko

We extend our relativistic theory of gravitational structure of composite hadrons to obtain the pion gravitational form factors at large momentum transfers. The approach was used in the case of intermediate region of the variable in our…

High Energy Physics - Phenomenology · Physics 2023-12-05 A. F. Krutov , V. E. Troitsky

Lattice simulations of QCD have produced precise estimates for the masses of the lowest-lying hadrons which show excellent agreement with experiment. By contrast, lattice results for the vector and axial vector form factors of the nucleon…

High Energy Physics - Lattice · Physics 2011-09-23 B. B. Brandt , S. Capitani , M. Della Morte , D. Djukanovic , J. Gegelia , G. von Hippel , A. Juttner , B. Knippschild , H. B. Meyer , H. Wittig

We give a determination of the phenomenological value of the Wilson (or gradient) flow scales t0 and w0 for 2+1 flavours of dynamical quarks. The simulations are performed keeping the average quark mass constant, which allows the approach…

High Energy Physics - Lattice · Physics 2015-08-25 V. G. Bornyakov , R. Horsley , R. Hudspith , Y. Nakamura , H. Perlt , D. Pleiter , P. E. L. Rakow , G. Schierholz , A. Schiller , H. Stüben , J. M. Zanotti

We calculate the lowest-dimensional nonlocal quark and gluon condensates within the single instanton approximation of the instanton liquid model. As a result, we determine the values of average virtualities of quarks $\lambda_q^2$ and…

High Energy Physics - Phenomenology · Physics 2014-11-17 A. E. Dorokhov , S. V. Esaibegyan , S. V. Mikhailov

We present a first machine learning-based decoding of the gluonic structure of the proton from lattice QCD using a variational autoencoder inverse mapper (VAIM). Harnessing the power of generative AI, we predict the parton distribution…

High Energy Physics - Phenomenology · Physics 2025-07-25 Brandon Kriesten , Alex NieMiera , William Good , T. J. Hobbs , Huey-Wen Lin

We analyze the instanton transitions in the framework of the gauge invariant variational calculation in the pure Yang-Mills theory. Instantons are identified with the saddle points in the integration over the gauge group which projects the…

High Energy Physics - Phenomenology · Physics 2016-08-25 William E. Brown , Juan P. Garrahan , Ian I. Kogan , Alex Kovner

The correlator of vector and nonsinglet axial-vector currents in the external electromagnetic field is calculated within the instanton liquid model of QCD vacuum. In general the correlator has two Lorentz structures: longitudinal w_L and…

High Energy Physics - Phenomenology · Physics 2009-01-07 A. E. Dorokhov

The non-perturbative quark-gluon interaction depends significantly on the value of the quark mass. In particular, in the light quark mass regime, correlations are strongly influenced by dynamics associated to chiral symmetry breaking. We…

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

We perform a nonperturbative lattice calculation of the complex phase and modulus of the pion form factor in the timelike momentum region using the finite-volume technique. We use two ensembles of 2+1-flavor overlap fermion at pion masses…

High Energy Physics - Lattice · Physics 2015-03-18 Xu Feng , Sinya Aoki , Shoji Hashimoto , Takashi Kaneko