A new KL0 decay channel

In this Letter the rate for the decay KL0⇒K±e∓(ν¯/ν) of (0.0979±0.0037)s−1 has been calculated in the hypothesis of the conserved vector current and, assuming the CP violation very small, the two rates for the decay KL0¯⇒K−e+ν and KL0⇒K+e−ν¯ are foreseen very similar. Such a decay was never taken into account in the past, due to the very low phase space factor yielding a branching ratio for KL decay BR=(0.5071±0.0199)×10−8. Now, with the very intense K beams foreseen at KEK, J-PARC, BNL, CERN and LNF the observation of this decay seems feasible. With samples of very large statistical significance a new measurement of the indirect CP violation parameter ϵ could be done.