Longitudinal spin transfer to Λ and \bar \Lambda in polarized proton-proton collisions at √s = 200 GeV at STAR

The longitudinal spin transfer D_LL of Λ and $$\bar \Lambda$$ hyperons is expected to be sensitive to the helicity distribution function of strange (anti-)quarks, and to the polarized fragmentation functions. We report new results on D_LL, extracted from √s = 200 GeV polarized pp collisions recorded at the STAR detector during the 2009 RHIC run. These new results cover mid-rapidity |η| < 1.2, with extended p_T up to 6 GeV/c.