The two pion decay modes of neutral kaons can be decomposed into a
and 
amplitude. This allows to make use
of the fact that the amplitude is the dominant decay mode
of neutral kaons:
Allowing for 
violation in the 
amplitudes,
we can write (use 
) :
where 
are the weak decay amplitudes, 
the strong interaction phase shifts and 
violating
amplitudes.
Assuming only small 
violation, we can write for any CP=+1
final state:
In addition to violation occuring in 
mixing
we get two additional terms:
,
a purely imaginary part from a possible phase difference of the
decay amplitude compared to 
,
,
a real part which can either come directly from violation
of the decay amplitudes or from an interference of two decay amplitudes
with a different phase. In the case of only one contributing amplitude,
this term is violating.
For the 
and 
final states, we obtain by using
only terms linear in 
( 
):
with
or using eq.34:
with
using that 
and therefore 
.
In the limit of a dominating violation in the
amplitude, e.g. 
, we can write:
