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dc.contributor.authorAnikin, I. V.
dc.contributor.authorDorokhov, A. E.
dc.contributor.authorTomio, Lauro [UNESP]
dc.identifier.citationPhysics of Particles and Nuclei, v. 31, n. 5, p. 509-537, 2000.
dc.description.abstractThe covariant quark model of the pion based on the effective nonlocal quark-hadron Lagrangian involving nonlocality induced by instanton fluctuations of the QCD vacuum is reviewed. Explicit gauge invariant formalism allows us to construct the conserved vector and axial currents and to demonstrate their consistency with the Ward-Takahashi identities and low-energy theorems. The spontaneous breaking of chiral symmetry results in the dynamic quark mass and the vertex of the quark-pion interaction, both momentum-dependent. The parameters of the instanton vacuum, the average size of the instantons, and the effective quark mass are expressed in terms of the vacuum expectation values of the lowest dimension quark-gluon operators and low-energy pion observables. The transition pion form factor for the processes γ*γ → π0 and γ*γ → π0 is analyzed in detail. The kinematic dependence of the transition form factor at high momentum transfers allows one to determine the relationship between the light-cone amplitude of the quark distribution in the pion and the quark-pion vertex function. Its dynamic dependence implies that the transition form factor γ*γ → π0 at high momentum transfers is acutely sensitive to the size of the nonlocality of nonperturbative fluctuations in the QCD vacuum. In the leading twist, the distribution amplitude and the distribution function of the valence quarks in the pion are calculated at a low normalization point of the order of the inverse average instanton size ρc-1. The QCD results are evolved to higher momentum transfers and are in reasonable agreement with available experimental data on the pion structure. Copyright © 2000 by MAIK Nauka/Interperiodica (Russia).en
dc.relation.ispartofPhysics of Particles and Nuclei
dc.titlePion structure in the instanton liquid modelen
dc.contributor.institutionJoint Institute for Nuclear Research
dc.contributor.institutionUniversidade Estadual Paulista (UNESP)
dc.description.affiliationLaboratory of Theoretical Physics Joint Institute for Nuclear Research, Dubna, Moscow oblast 141980
dc.description.affiliationInst. de Fis. Téorica UNESP, Rua Pamplona 145, São Paulo 01405-900
dc.description.affiliationUnespInst. de Fis. Téorica UNESP, Rua Pamplona 145, São Paulo 01405-900
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