Search for exclusive B decays to J and eta or pi(0) with the L3 detector

Abstract A search for exclusive decays of B d 0 and B s 0 mesons has been performed in the channels B d 0 → J η , B s 0 → J η , B d 0 → J π 0 and B s 0 → J π 0 . The data sample consisted of more than three and half million hadrozic Z decays collected by the L3 experiment at LEP from 1991 through 1995. No candidate events have been observed for any of the modes thus determining upper limits at 90% confidence level: 3.2 × 10 −4 on Br(B d 0 → J π 0 ) and the first experimental limits: Br(B d 0 → J η ) −3 , Br(B s 0 → J η ) −3 , Br(B s 0 → J π 0 ) −3 .