2020 Impact factor 4.590
Particles and Fields
Eur. Phys. J. C 4, 387-407
DOI 10.1007/s100529800924

## Observation of doubly-charmed B decays at LEP

The ALEPH Collaboration

R. Barate et al.

Laboratoire de Physique des Particules (LAPP), IN2P3-CNRS, F-74019 Annecy-le-Vieux Cedex, France

Abstract
A search for doubly-charmed B decays with both charmed mesons reconstructed is performed, using about 3.8 million hadronic Z decays recorded with the ALEPH detector at LEP. A clear signal is observed in the channels and (where D can be either a D0, a D+ or a D*+), providing the first direct evidence for doubly-charmed B decays involving no production. Evidence for associated and production in the decays is also presented and some candidates for completely reconstructed decays , and are observed. Furthermore, candidates for the two-body Cabibbo suppressed decays and are also observed. Measurements of the corresponding branching fractions are extracted.