Combined analysis of the K + K − interaction using near - threshold pp → ppK + K − data

The K+K− final state interaction was investigated based on both the K+K− invariant mass distributions measured at excess energies of Q = 10 and 28 MeV and the near threshold excitation function for the pp → ppK+K− reaction. The K+K− final state enhancement factor was parametrized using the effective range expansion. The effective range of the K+K− interaction was estimated to be Re(bK+K− ) = −0.1 ± 0.4stat ± 0.3sys fm and Im(bK+K− ) = 1.2statsys −0.2stat−0.0sys fm, and the determined real and imaginary parts of the K+K− scattering length amount to |Re(aK+K− )| = 8.0+6.0stat −4.0stat fm and Im(aK+K− ) = 0.0+20.0stat −5.0stat fm.