Author(s): The SLD Collaboration Presenting author: Tracy Usher Corresponding author's e-mail: usher@slac.stanford.edu Title of the presentation: An improved measurement of b-quark fragmentation function in Z^0 decays at SLD Link to the full paper: Session of 1st preference: 1-Hard High Energy QCD and Structure Functions Session of 2nd preference: 4-Heavy Flavor   Abstract   We present an improved measurement of the inclusive b quark fragmentation function in Z^0 decays using a novel kinematic B energy reconstruction technique. The measurement is based on 350,000 hadronic Z^0 events recorded in the SLD experiment at SLAC from 1997 to 1998. The small and stable SLC beam spot and the CCD vertex detector are used to reconstruct topological B-decay vertices with high efficiency and purity, and to provide precise measurements of the kinematic quantities. We measure the B energy with good efficiency and resolution over the full kinematic range. We compare the measured scaled B energy distribution with predictions of several models of b quark fragmentation and functional forms of the B energy distribution. Many are excluded by the data. The average scaled energy of the weakly decaying B hadron is measured with an experimental precision of 0.006 and a model-dependence of 0.004 (preliminary).