PHYSICAL REVIEW LETTERS 17OCTOBER 1966 17 The absolute rates such as T{r + ) can be replaced by branching ratios r(r + )/r(X + -all) or T(T + )/T(K + -^M + v) 9 etc., since CPT in variance ensures r (IT 4 "-all) = T(iC""-all), etc. We note that the equality T(T + ) + T(T ,+ ) = r(T~) + r{T'~) is also guaranteed by CPT invar iance.