Speakers
Description
The beam-spin induced polarization of $\Lambda$ and $\bar{\Lambda}$ hyperons produced in deep-inelastic scattering of longitudinally polarized positrons from unpolarized nucleons has been investigated by the HERMES experiment at a positron beam energy of 27.6 GeV impinging on hydrogen, deuterium, and various heavier gas targets. The two spin-transfer coefficients $D_{LX}$ and $D_{LZ}$ are extracted and are found to be small and mostly compatible with zero within their statistical and systematic uncertainties, essentially independent of the relevant kinematic variables. The results constrain novel spin-dependent fragmentation functions, among others the helicity fragmentation function describing the hadronization of longitudinally polarized quarks into longitudinally polarized hadrons.