Longitudinal $\Lambda$ and $\bar{\Lambda}$ polarization in the COMPASS experiment

At the COMPASS experiment at CERN, $\Lambda$ and $\bar{\Lambda}$ particles are produced with high statistics in deep inelastic scattering processes of 160 GeV/c polarized $\mu^{+}$ off a $^{6}$LiD target. The main focus of the research is the understanding of the longitudinal $\Lambda$ and $\bar{\Lambda}$ polarization and the spin transfer mechanism from quarks to hadrons through the fragmentation process. The results provide useful information to test different model predictions, which describe spin effects in hyperon production and the quark-antiquark asymmetry of the nucleon spin structure such as the polarization of $s$ and $\bar{s}$ quarks in the nucleon. Preliminary results from data collected during 2002 and 2003 are presented for the current fragmentation region. We will compare our results with other measurements and discuss the dependence of the $\Lambda$ and $\bar{\Lambda}$ polarization on various kinematic variables.