Search for the Decays {ital B}{sup 0}{r_arrow}{ital D}{sup ({asterisk})+}{ital D}{sup ({asterisk}){minus}}

Using the CLEO-II data set we have searched for the decays B{sup 0}{r_arrow}D{sup (*)+}D{sup (* ){minus}} . We observe one candidate signal event for the decay B{sup 0}{r_arrow}D{sup *+}D{sup *{minus}} with an expected background of 0.022{plus_minus}0.011 events. This yield corresponds to a branching fraction of B(B{sup 0}{r_arrow}D{sup *+}D{sup *{minus}} )=[5.3{sup +7.1}{sub {minus}3.7}(stat ){plus_minus}1.0(syst)]{times} 10{sup {minus}4} and an upper limit of B(B{sup 0}{r_arrow}D{sup *+}D{sup *{minus}} ){lt}2.2{times}10{sup {minus}3} at the 90% C.L. We see no significant excess of signal above the expected background level in the other modes, and we calculate the 90% C.L.upper limits on the branching fractions to be B(B{sup 0}{r_arrow}D{sup *{plus_minus}}D{sup {minus_plus}}){lt}1.8{times}10{sup {minus}3} and B(B{sup 0}{r_arrow}D{sup +}D{sup {minus}}){lt}1.2{times}10{sup {minus}3} . {copyright} {ital 1997} {ital The American Physical Society}