Regular Article - Theoretical Physics
Kaon electromagnetic form factors in dispersion theory
Helmholtz-Institut für Strahlen- und Kernphysik (Theorie) and Bethe Center for Theoretical Physics, Universität Bonn, 53115, Bonn, Germany
2 Albert Einstein Center for Fundamental Physics, Institute for Theoretical Physics, University of Bern, Sidlerstrasse 5, 3012, Bern, Switzerland
3 Physik-Institut, Universität Zürich, Winterthurerstrasse 190, 8057, Zürich, Switzerland
4 Paul Scherrer Institut, 5232, Villigen PSI, Switzerland
Accepted: 17 April 2022
Published online: 11 May 2022
The electromagnetic form factors of charged and neutral kaons are strongly constrained by their low-energy singularities, in the isovector part from two-pion intermediate states and in the isoscalar contribution in terms of and residues. The former can be predicted using the respective partial-wave amplitude and the pion electromagnetic form factor, while the latter parameters need to be determined from electromagnetic reactions involving kaons. We present a global analysis of time- and spacelike data that implements all of these constraints. The results enable manifold applications: kaon charge radii, elastic contributions to the kaon electromagnetic self energies and corrections to Dashen’s theorem, kaon boxes in hadronic light-by-light (HLbL) scattering, and the region in hadronic vacuum polarization (HVP). Our main results are: , for the charged and neutral radii, for the elastic contribution to the violation of Dashen’s theorem, for the charged kaon box in HLbL scattering, and , for the HVP integrals around the resonance. The global fit to gives , for the resonance parameters including vacuum-polarization effects.
© The Author(s) 2022
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