First Observation of $\Lambda$ Hyperon Transverse Polarization in $\psi (3686)\to \Lambda \bar{\Lambda }$

BESIII Collaboration, M. Ablikim, M. N. Achasov +687

Based on $(448.1\pm 2.9)\times 10^6$ $\psi (3686)$ events collected with the BESIII detector at the BEPCII collider, we present the first observation of spin transverse polarization of…