$\Lambda$ polarization with a transversely polarized proton target at COMPASS

The transverse polarization of $\Lambda$ and $\bar{\Lambda}$ hyperons is investigated at the COMPASS experiment at CERN. In 2007 a 160 GeV/c longitudinally polarized muon beam and a transversely polarized $NH_{3}$ target was employed to study events in semi-inclusive deep-inelastic scattering. Preliminary results for the $\Lambda$ and $\bar{\Lambda}$ polarizations extracted from this new data set are presented as a function of $x_{Bj}$ and $z$. The polarizations of $\Lambda$ and $\bar{\Lambda}$ are compatible with zero within their error bars and are thus unpolarized and with no dependence on $x_{Bj}$ or $z$.