Re-evaluation of the relative decay rate of long-lived and short-lived neutral kaons into two neutral pions

Some time ago the CP-violating decay K/sub L//sup 0/ to pi /sup 0/ pi /sup 0/ was discovered by a CERN-RHEL-Aachen group, using a multiplate spark chamber arrangement near a K/sub L//sup 0/ beam, derived from the CERN proton synchrotron. These data have been reanalysed performing a least-squares fit to each event. The average errors of directions and energies of the detected photons have been experimentally determined on samples of 4-shower and 6-shower events. A normalization on regenerated K/sub s//sup 0/ to 2 pi /sup 0/ decays has been used. The value of mod eta /sub 00/ mod = mod A(K/sub L//sup 0/ to 2 pi /sup 0/)/A(K/sub s//sup 0/ to 2 pi /sup 0/) mod = (2.4+or-0.5).10/sup -3/ is consistent with T violation and CPT conservation in K/sub L//sup 0/ to 2 pi decay and with the existence of a superweak interaction. (32 refs).