Observation of $\Xi^{-}$ Hyperon Transverse Polarization in
$\psi(3686)\rightarrow\Xi^{-}\bar\Xi^{+}$
Observation of $\Xi^{-}$ Hyperon Transverse Polarization in
$\psi(3686)\rightarrow\Xi^{-}\bar\Xi^{+}$
Using a sample of $(448.1~\pm~2.9)$ $\times 10^{6}$ $\psi(3686)$ decays collected with the BESIII detector at BEPCII, we report an observation of $\Xi^{-}$ transverse polarization with a significance of $7.3 \sigma$ in the decay $\psi(3686)\rightarrow\Xi^{-}\bar\Xi^{+}$ ($\Xi^{-}\rightarrow\pi^{-}\Lambda$, $\bar\Xi^{+}\rightarrow\pi^{+}\bar\Lambda$, $\Lambda\to p\pi^{-}$, $\bar\Lambda\to\bar{p}\pi^{+}$). The relative phase of the electric and magnetic form factors is …