Characteristics of theS-WaveK¯KEnhancement at 1300 MeV

Our high-statistics experiment on ${\pi }^{-}p\to K^{-}{K}^{+}n$ and ${\pi }^{+}n\to K^{-}{K}^{+}p$ at 6 GeV/c confirms the $\overline{K}K$ $S$-wave enhancement near 1300 MeV recently observed by Cason et al. in ${\pi }^{-}p\to K_S^{}{}_{}{}^{0}K_S^{}{}_{}{}^{0}n$. Using the $P$-wave amplitude and the isospin dependence of interfering $\overline{K}K$ states, we resolve partial-wave ambiguities and find the $S$ wave to be dominantly isospin $I=0$, with a slow variation of phase. This excludes the interpretation of Cason et al. that the $S$ wave enhancement is a narrow $I=1$ state.