Transverse Λ polarization from a transversely polarized proton target at the COMPASS experiment

The measurement of the transverse spin quark distribution functions ΔT q(xBj) is an important part of the physics program of the COMPASS experiment at CERN. These transversity distributions, being chiral-odd objects, are not accessible in inclusive deep-inelastic scattering (DIS), requiring the presence of another chiral-odd object. At COMPASS, ΔT q(xBj) can be measured in semi-inclusive deep-inelastic scattering (SIDIS), where a promising channel is the spin transfer to the Λ hyperons. Here, the fragmentation functions ΔTDΛ q (z) provide the other chiral-odd object. In this thesis, the semi-inclusive Λ production mechanism is introduced to show the connection between a potentially measured Λ polarization PΛ and the ΔT q(xBj) functions. An expression for the angular distribution of the weak decay Λ → pπ− is used which allows to extract PΛ independent of acceptance effects of the spectrometer. In 2007 a 160 GeV/c longitudinally polarized muon beam and a transversely polarized NH3 target were employed in the COMPASS experiment. Based on the full 2007 statistics with transverse target spin configuration, the Λ and Λ polarizations are analyzed as a function of xBj and z. The Λ and Λ hyperons are unpolarized within their statistical errors and show no dependence on either xBj or z.