Precise measurement of the b-quark fragmentation function in Z0 boson decays

We have developed a new technique for inclusive reconstruction of the energy of B hadrons. The excellent efficiency and resolution of this technique allow us to make the must precise determination of the b-quark fragmentation function, using e(+)e(-) --> Z(0) decays recorded in the SLAG Large Detector experiment. We compared our measurement with the predictions of a number of fragmentation models. We excluded several of these models and measured the average scaled energy of weakly decaying B hadrons to be [x(B)] = 0.714 +/- 0.005(stat) +/- 0.007(syst) +/- 0.002 (model dependence).