Semileptonic B decays to narrow orbitally-excited charm mesons using the OPAL detector at LEP

The decay chain b &rarr; B&macr; &rarr; D<super>**0</super> &ell;<super> &minus;</super><math> <f> <a><ac><g>n</g></ac><ac>&d1;</ac></a></f> </math><italic>X</italic>, D<super>**0</super> &rarr; D<super>*+</super>&pi;<super> &minus;</super>, D<super>*+</super> &rarr; D<super>0</super>&pi;<super>+</super>, D<super>0</super> &rarr; (K&pi; or K 3&pi;) was identified in a sample of 3.9 million hadronic Z decays collected with the OPAL detector at LEP. The branching ratio BR (b &rarr; B&macr;) &times; BR (B&macr; &rarr; <math> <f> <rm>D⁰<inf>1</inf></rm></f> </math> &ell;<super>&minus;</super><math> <f> <a><ac><g>n</g></ac><ac>&d1;</ac></a></f> </math><italic>X</italic>) &times; BR(<math> <f> <rm>D⁰<inf>1</inf></rm></f> </math> &rarr; D<super>*+</super>&pi;<super>&minus;</super>) was measured to be (2.64 &plusmn; 0.79 (stat) &plusmn; 0.39 (syst)) &times; 10<super>&minus;3 </super> for the <italic>J<super>P</super></italic> = 1<super>+</super> (<math> <f> <rm>D⁰<inf>1</inf></rm></f> </math>) state. For decays into the <italic>J<super>P</super></italic> = 2<super> +</super> (<math> <f> <rm>D^*0<inf>2</inf></rm></f> </math>) state, an upper limit of 1.4 &times; 10<super>&minus;3</super> was placed on the branching ratio at the 95% confidence level.