Electromagnetic form factors of the pion and kaon from the instanton vacuum

Abstract

We investigate the pion and kaon (pi^+, K^+, K^0) electromagnetic form factors in the space-like region: Q^2 ~< 1 GeV, based on the gauged low-energy effective chiral action from the instanton vacuum in the large N_c limit. Explicit flavor SU(3) symmetry breaking is taken into account. The nonlocal contributions turn out to be crucial to reproduce the experimental data. While the pion electromagnetic form factor is in good agreement with the data, the kaon one seems underestimated. We also calculate the electromagnetic charge radii for the pion and kaon: <r^2>_{pi^+}=0.455 fm^2, <r^2>_{K^+}=0.486 fm^2 and <r^2>_{K^0}=-0.055 fm^2 without any adjustable free parameter except for the average instanton size and inter-instanton distance, and they are compatible with the experimental data. The low-energy constant L_9 in the large N_c limit is estimated to be 8.42*10^{-3} from the pion charge radius.

11 pages, 5 figures, submitted to PRD

References in corpus (10)

• Determination of the Charged Pion Form Factor at Q2=1.60 and 2.45 (GeV/c)2
• The pion form factor from lattice QCD with two dynamical flavours
• Low energy constants of \chiPT from the instanton vacuum model
• Magnetic susceptibility of the QCD vacuum
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• 1/N_c corrections to the magnetic susceptibility of the QCD vacuum
• Exploring the Chiral Regime of QCD in the Interacting Instanton Liquid Model
• QCD condensates with flavor SU(3) symmetry breaking from the instanton vacuum
• Pion form factor in the Kroll-Lee-Zumino model
• Kaon semileptonic decay (K_{l3}) form factors from the instanton vacuum

Cited by in corpus (8)

• The pion's electromagnetic form factor at small momentum transfer in full lattice QCD
• Spin structure of the pion from the instanton vacuum
• Stability of the pion and the pattern of chiral symmetry breaking
• Pion electromagnetic form factor, perturbative QCD, and large-Nc Regge models
• Pions valence quark distributions in asymmetric nuclear matter at finite temperature
• Pion weak decay constant at finite density from the instanton vacuum
• Electroweak properties of kaons in a nuclear medium
• Heavy-light quark systems from the QCD instanton vacuum: $N_f=1$ light flavor case