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

Abstract

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.