Generalized Dalitz plot analysis of the near-threshold pp→ppK + K - reaction in view of the K + K - final state interaction

The excitation function for the pp{yields}ppK{sup +}K{sup -} reaction revealed a significant enhancement close to threshold that may plausibly be assigned to the influence of the pK{sup -} and K{sup +}K{sup -} final-state interactions. In an improved reanalysis of COSY-11 data for the pp{yields}ppK{sup +}K{sup -} reaction at excess energies of Q=10 and 28 MeV, including the proton-K{sup -} interaction, the enhancement is confirmed. Invariant mass distributions for the two- and three-particle subsystems allow us to test at low excess energies the ansatz and parameters for the description of the interaction in the ppK{sup +}K{sup -} system as derived from the COSY-ANKE data. Finally, based for the first time on the low-energy K{sup +}K{sup -} invariant mass distributions and the generalized Dalitz plot analysis, we estimate the scattering length for the K{sup +}K{sup -} interaction to be |Re(a{sub K{sup +}}{sub K{sup -}})|=0.5{sub -0.5}{sup +4.0} fm and Im(a{sub K{sup +}}{sub K{sup -}})=3.0{+-}3.0 fm.