Lawrence Berkeley National Laboratory

The transverse polarization of inclusively produced Λ and Λ̄ hyperons has been studied at HERMES using the 27.6 GeV positron beam of HERA and an internal gas target. From the data taken in the years 1996-2000, 386,000 Λ and 72,000 Λ̄ events have been reconstructed, allowing the measurement of the Λ and Λ̄ polarizations with high statistical accuracy. Averaged over the full kinematic range of the data, the transverse polarizations were measured to be PnΛ = 5.4 ± 0.5 (stat) ± 1.5 (syst) % and PnΛ̄ = -4.0 ± 1.3 (stat) ± 1.2 (syst) %. The dependence of the polarization on several transverse momentum PT and on the hyperons' light cone momentum fraction ζ has been investigated.