Model-independent determination of the parity of $\Xi$ hyperons

TL;DR

The paper presents a model-independent method to determine the parity of $ ext{Xi}$ hyperons using reflection symmetry and polarization measurements, applicable universally across the hyperon spectrum.

Contribution

It introduces a universal, model-independent relation between the transverse spin-transfer coefficient and hyperon parity, based on Bohr's theorem, for various reactions involving $ ext{Xi}$ hyperons.

Findings

The parity of $ ext{Xi}$ hyperons can be directly determined by measuring $K_{yy}$.

The method applies to both $ar{K}N$ and photoreaction processes.

Feasibility is enhanced by the self-analyzing property of $ ext{Xi}$ hyperons.

Abstract

Based on reflection symmetry in the reaction plane, it is shown that measuring the transverse spin-transfer coefficient $K_{yy}$ in the $\bar{K}N \to K\Xi$ reaction directly determines the parity of the produced cascade hyperon in a model-independent way as $\pi_\Xi =K_{yy}$, where $\pi_\Xi =\pm 1$ is the parity. This result based on Bohr's theorem provides a completely general, universal relationship that applies to the entire hyperon spectrum. A similar expression is obtained for the photoreaction $\gamma N \to K K \Xi$ by measuring both the double-polarization observable $K_{yy}$ and the photon-beam asymmetry $\Sigma$. Regarding the feasibility of such experiments, it is pointed out that the self-analyzing property of the $\Xi$'s can be invoked, thus requiring only a polarized nucleon target.