P oS(DIS 2010)232 Longitudinal and transverse Λ polarization at COMPASS

At the COMPASS experiment Λ and Λ particles are produced with high statistics in deep inelas-tic scattering (DIS) processes of 160 GeV/c polarized muons. Since both, beam and target, are polarized, various studies on the Λ polarization are possible. We present results on the longitu-dinal polarization transfer from muons to Λ hyperons produced by scattering off an unpolarized isoscalar target and preliminary results on the transverse Λ polarization with a transversely polar-ized proton target. The Λ and Λ polarization can be studied by measuring the acceptance corrected angular distribution of its decay products. The longitudinal spin transfers to Λ and Λ produced in the current fragmentation region exhibit different behaviours as a function of xB j and xF. The xB j and xF dependences of Λ polarization are compatible with zero, while Λ polarization tends to increase with xF. Information on the transversely polarized quark distributions ∆T q(x) in the nucleon can be accessed by measuring the transverse Λ and Λ polarizations, which refer to a spin correlation between the transversely polarized nucleons and Λs. The transverse polarization is measured as function of xB j and z and found to be compatible with zero