For discussion, see note on Dalitz plot parameters in the ${{\mathit K}^{\pm}}$ section of the Particle Listings above. For definitions of $\mathit a_{\mathit v}$, $\mathit a_{\mathit t}$, $\mathit a_{\mathit u}$, and $\mathit a_{\mathit y}$, see the earlier version of the same note in the 1982 edition of this $\mathit Review$ published in Physics Letters 111B 70 (1982).
$\vert $matrix element$\vert ^2$ = 1 + $\mathit g{}\mathit u$ + $\mathit h{}\mathit u{}^{2}$ + $\mathit j{}\mathit v$ + $\mathit k{}\mathit v{}^{2}$ + $\mathit f{}\mathit u{}\mathit v$ where $\mathit u$ = ($\mathit s_{3}$ $−$ $\mathit s_{0}$) $/$ ${{\mathit m}^{2}}_{{{\mathit \pi}}}$ and $\mathit v$ = ($\mathit s_{2}$ $−$ $\mathit s_{1}$) $/$ ${{\mathit m}^{2}}_{{{\mathit \pi}}}$