K−pAmplitudes near theΛ(1520)

Abstract

${\overline{K}}^{0}n$, $\Lambda {\pi }^0$, and ${\Sigma }^0{\pi }^0$ final-state cross sections and $\Lambda {\pi }^0$ and ${\Sigma }^0{\pi }^0$ polarizations are obtained in $K^{-}p$ interactions, for $P_{K^{-}}$ in the range 350-430 MeV/c, near the $\Lambda \mathrm{}\left(1520\right)\mathrm{}$ resonance. Two fits to the partial-wave amplitudes have been found, both assuming a standard Breit-Wigner amplitude for the $\Lambda \mathrm{}\left(1520\right)\mathrm{}$ resonance and a constant-scattering-length $D_{\frac{3}{2}}$ isospin-1 amplitude, but differing in their treatment of the $S$- and $P$-wave backgrounds. One method used a constant $K$ matrix, the other a momentum-dependent effective-range expansion for the inverse of the $K$ matrix. From the fitted partial waves, an upper limit of 10% is set for an isospin mixing between the $\Lambda {\pi }^0$ and ${\Sigma }^0{\pi }^0$ amplitudes.