Sprecher
Beschreibung
The hyperons are produced with a non-zero spin polarization that is
straight-forward to parameterize in processes involving virtual photons or
vector mesons, enable direct and precise CP violation tests. These CP tests
can be performed on e.g. $J/\psi,\psi' \to\Lambda\bar{\Lambda}$, $\Xi\bar{\Xi}$ and $\Sigma\bar{\Sigma}$. For the cascade hyperon decay the exclusive measurement of the final state particles allows for three independent CP-symmetry tests and the determination of the strong and weak phase differences. Thanks to the world’s largest data samples at the $J/\psi$ and $\psi'$ resonances collected at the BESIII experiment, the multi-dimensional analyses making use of polarization and entanglement have been performed for these processes.
