An analysis is made o f the limits on the possible departures from
CP
-,
T
-, and
TCP
-invariance, both in the structure of K
L
and K
S
states and in the decay amplitudes to xx and xIv channels. A small violation of the requirements of
CP
- and
T
-invariance on the structure of K
L
and K
S
states can be deduced under quite plausible assumptions, but there is no evidence of any other departure from the requirements of
CP
-, or
T
-, or
TCP
-in variance. However, the present limit for one measure 8 of
TCP
-noninvariance is
several times larger
than the estim ated value of the corresponding
CP
- and
T
-noninvariance parameter or = Re<K
L
|K
S
>. Taking a conservative view of the experimental data, symmetry-violating parts of decay amplitudes are lim ited to better than 1 % for the
I
= 0 channel and to within a small percentage for the
I
= 2 channel, in relative magnitude. The corresponding limits which can be deduced for leptonic decay amplitudes are som ewhat larger but there are indications that symmetry-violating amplitudes are unlikely to exceed a small percentage in relative magnitude.
Direct CP violation in neutral kaon decays
