Determination of vertical bar V{sub ub} vertical bar from Measurements of the Inclusive Charmless Semileptonic Partial Rates of B Mesons using Full Reconstruction Tags

We present a measurement of the Cabibbo-Kobayashi-Maskawa matrix element vertical bar V{sub ub} vertical bar, based on 253 fb{sup -1} of data collected by the Belle detector at the KEKB e{sup +}e{sup -} asymmetric collider. Events are tagged by fully reconstructing one of the B mesons, produced in pairs from {upsilon}(4S). The signal for b{yields}u semileptonic decay is distinguished from the b{yields}c background using the hadronic mass M{sub X}, the leptonic invariant mass squared q{sup 2} and the variable P{sub +}{identical_to}E{sub X}- vertical bar p{yields}{sub X} vertical bar. The results are obtained for events with p{sub l}*{>=}1 GeV/c, in three kinematic regions (1) M{sub X}