Study of ambiguities in $\pi^-p\to \Lambda K^0$ scattering amplitudes

Understand

Amplitudes for the reaction $\pi^-p\to \Lambda K^0$ are reconstructed from data on the differential cross section $d\sigma/d\Omega$, the recoil polarization $P$, and on the spin rotation parameter $\beta$.

• At low energies, no data on $\beta$ exist, resulting in ambiguities.
• An approximation using $S$ and $P$ waves leads only to a fair description of the data on $d\sigma/d\Omega$ and $P$; in this case, there are two sets of amplitudes.
• Including $D$ waves, the data on $d\sigma/d\Omega$ and $P$ are well reproduced by the fit but now, there are several distinct solutions which describe the data with identical precision.