The European Physical Journal C

ISSN: 1434-6044 (printed version)
ISSN: 1434-6052 (electronic version)

Table of Contents

Abstract Volume 4 Issue 3 (1998) pp 387-407
DOI 10.1007/s100529800924

experimental physics:
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

Received: 6 March 1998 / Published online: 23 June 1998

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 ${\rm B\rightarrow D_s \bar D}(X)$ and ${\rm B\rightarrow D \bar D}(X)$ (where D can be either a D$^0$, a D$^+$ or a D$^{*+}$), providing the first direct evidence for doubly-charmed B decays involving no ${\rm D_s}$ production. Evidence for associated ${\rm K^0_S}$ and ${\rm K^{\pm}}$ production in the decays ${\rm B\rightarrow D \bar D}(X)$ is also presented and some candidates for completely reconstructed decays ${\rm B\rightarrow D_s \bar D}(n\pi)$, ${\rm B\rightarrow D \bar D K^0_S}$ and ${\rm B\rightarrow D \bar D K^\pm}$ are observed. Furthermore, candidates for the two-body Cabibbo suppressed decays ${\rm B^0\rightarrow D^{*-}D^{*+}}$ and ${\rm B^-\rightarrow D^{(*)0}D^{(*)-}}$ are also observed. Measurements of the corresponding branching fractions are extracted.

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Online publication: July 6, 1998
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