Transverse and Longitudinal Lambda Polarization in Lepton Scattering by Unpolarized Nucleons at HERMES

Transverse and longitudinal polarization of $\Lambda$ hyperons has been studied. The transfer of polarization from high-energy positron to $\Lambda$ hyperon has been measured. The longitudinal spin transverse coefficient is found to be $D_{LL′}^{\Lambda} = 0.11\pm 0.10(stat) \pm 0.03(sys)$. The transverse polarization of $\Lambda$ and $\bar{\Lambda}$ hyperons has been measured in inclusive quasireal photoproduction process for various target nuclei. The polarization observed is positive for light target nuclei and compatible with zero for heavy target nuclei