Four-lepton decays and the electromagnetic radius of the K meson

Rare four-fermion K-meson decay processes are studied. These processes give information on the weak-electromagnetic structure of the pseudoscalar mesons. The probabilities for the decays K+→μ+νe+e- and K+→e+νe+e- are calculated using the schoonschIp program. Experimental data obtained at CERN using an intense charged-K-meson beam are used to find the value of the axial form factor c0 characterizing these decays, and the relation c0 = (1)/(3) M2/sub K/ to the kaon electromagnetic radius is checked. The K-meson rms radius ()/sup 1/2/ = 0.67 +- 0.07 F is determined assuming that this relation is valid. This radius agrees within the error with the result of the direct experimental determination of this quantity