The K-meson form factor and charge radius: linking low-energy data to future Jefferson Laboratory measurements

Starting from a successful model of the \(\pi \)-meson electromagnetic form factor, we calculate a similar form factor, \(F_{K}(Q^{2})\), of the charged K meson for a wide range of the momentum transfer squared, \(Q^{2}\). The only remaining free parameter is to be determined from the measurements of the K-meson charge radius, \(r_{K}\). We fit this single parameter to the published data of the NA-7 experiment which measured \(F_{K}(Q^{2})\) at \(Q^{2}\rightarrow 0\) and determine our preferred range of \(r_{K}\), which happens to be close to recent lattice results. Still, the accuracy in the determination of \(r_{K}\) is poor. However, future measurements of the K-meson electromagnetic form factor at \(Q^{2}\lesssim 5.5\) GeV\(^{2}\), scheduled in Jefferson Laboratory for 2017, will test our approach and will reduce the uncertainty in \(r_{K}\) significantly.