Radiative corrections to the decaysKL0→e+e−andKL0→μ+μ−

We calculate the rates and lepton ({ital l}) invariant mass distributions for decays of the form 0{sup {minus}+}{r_arrow}l{sup +}l{sup {minus}}{gamma}, which are important radiative corrections to the purely leptonic decays 0{sup {minus}+}{r_arrow}l{sup +}l{sup {minus}}. Our approach uses the loop diagrams which arise by including the two photon intermediate state and we retain the imaginary parts of the loops{emdash}a radiative extension of the {open_quotes}unitarity bound{close_quotes} for the process. These results are compared with those obtained using a model in which the meson couples directly to the leptons. {copyright} {ital 1999} {ital The American Physical Society}