Proton Electro-Magnetic Form-Factors in the Instanton Liquid Model

Abstract

We report the first non-perturbative calculation of proton electro-magnetic form-factors in the Random Instanton Liquid Model (RILM) and in the Interacting Instanton Liquid Model (IILM). By calculating the ratio of appropriate three-point to two-point functions, we divide out the coupling constants and compare our results directly to some integral of the form-factors. Using various parameterizations of the electric form-factor $G_E(Q^2)$ at large $Q^2>3.5Ge{V}^2$, where it is not yet measured, we compare those with expected theoretical dependence. We find from this comparison that some distributions of charge are clearly excluded (e.g. the same as of the magnetic moment, $\mu G_E/G_M=1$, as well as the opposite scenario in which $\mu G_E/G_M$ rapidly approach zero), restricting possible behavior of the form-factor to rather narrow band. Furthermore, we found that our calculation of the nucleon form-factors is dominated by a configuration in which two out of three quarks interact with a $single$-instanton, in spite of the fact that the evaluated three-point function has rather large distances ($\sim 1.2fm$) between points. We also estimate the size of the scalar di-quark and found it to be very small, comparable to the typical instanton size.

arXiv comment10 pages, 8 figures. Version to appear in Phys. Rev. D

References in corpus (13)

• Instantons in QCD
• Diquark Bose Condensates in High Density Matter and Instantons
• The ratio of proton's electric to magnetic form factors measured by polarization transfer
• Evidence for the Role of Instantons in Hadron Structure from Lattice QCD
• Baryonic Correlation Functions in the Random Instanton Vacuum
• Hadronic Form Factors and Perturbative QCD
• Nucleon form factors and a nonpointlike diquark
• Selected nucleon form factors and a composite scalar diquark
• Systematic Study of the Single Instanton Approximation in QCD
• Hadronic Correlation Functions in the Interacting Instanton Liquid
• Implications of the ALEPH tau-Lepton Decay Data for Perturbative and Non-Perturbative QCD
• The Electromagnetic Pion Form Factor and Instantons
• Pion electromagnetic formfactor in the instanton vacuum

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• Exploring the Chiral Regime of QCD in the Interacting Instanton Liquid Model
• The Pauli form factor of the quark induced by instantons
• Instanton Contribution to the Electro-Magnetic Form Factors of the Nucleon
• Instanton Contribution to the Proton and Neutron Electric Form Factors
• Parameter free calculation of hadronic masses from instantons
• Instantons, Chiral Dynamics and Hadronic Resonances
• The Pauli Form Factor of Quark and Nontrivial Topological Structure of the QCD