Search for /ital b//r arrow//ital u/ transitions in exclusive hadronic /ital B/-meson decays

From a data sample of 242 000 /ital BB/bar // pairs collected with the CLEOdetector at the UPSILON(4/ital S/) resonance, we set upper limits for thebranching ratios for exclusive hadronic decays of /ital B/ mesons arising from/ital b//r arrow//ital u/ transitions. Model-dependent limits for the ratio of theKobayashi-Maskawa matrix elements /ital V//sub /ital ub///V/sub cb/ are presented.