Observation of the Polarization of Λ Hyperons Produced in the Interaction of K– Mesons with Nuclei

First results on the polarization of Λ hyperons inclusively produced on 26.5-GeV/c K^ - and π^ - beams are presented. The measurements were carried out using the SPASCHARM setup at the U-70 accelerator facility (Protvino, Russia) on nuclear targets in 2021 and 2022. The polarization of an Λ hyperon on the π^ - beam does not exceed several percent in most of the studied kinematic region. The data obtained on the K^ - -meson beam exhibit a significant positive polarization at large values of the Feynman variable xF and transverse momentum pT measured for the first time on nuclei.