Comments on the unitarity bound in K/sub L/0 → μ+μ-

Two alternatives to reconcile the present disagreement between experiment and the "simple" unitarity bound in K_L⁰→μ⁺μ⁻ are considered. These alternatives presume that CP violation does not play the dominant role (via Reε) in the resolution of this puzzle. They are (1) the introduction of new muonic interactions, and (2) the existence of a new pseudoscalar meson. The first alternative can already be eliminated by present experimental evidence. The second alternative must satisfy a number of restrictions.