First observation of the decay $\bar{B}^0_s \to D^0 K^{*0}$ and a measurement of the ratio of branching fractions $\frac{{\cal B}(\bar{B}^0_s \to D^0 K^{*0})}{{\cal B}(\bar{B}^0 \to D^0 \rho^0)}$ Auteur(s): Aaij R., Ben-Haim E., Benayoun M., David P., Del Buono L., Bonis De, Decamp D., Ghez Ph., Hopchev P., Lees J.-P., Machikhiliyan I.V., Minard M.-N., Pietrzyk B., T'Jampens S., Tisserand V., Arrabito L., Ajaltouni Z., Deschamps O., Henrard P., Jahjah Hussein M., Lefèvre R., Li Gioi L., Monteil S., Niess V., Perret P., Roa Romero D., Sobczak K., Barsuk S., Callot O., D'Almagne B. (Article) Publié: Physics Letters B, vol. 706 p.32-39 (2011) Ref HAL: in2p3-00637871_v1 Ref Arxiv: 1110.3676 DOI: 10.1016/j.physletb.2011.10.073 Ref. & Cit.: NASA ADS Exporter : BibTex | endNote Résumé: The first observation of the decay $\bar{B}^0_s \to D^0 K^{*0}$ using $pp$ data collected by the LHCb detector at a centre-of-mass energy of 7 TeV, corresponding to an integrated luminosity of 36 pb$^{-1}$, is reported. A signal of $34.4 \pm 6.8$ events is obtained and the absence of signal is rejected with a statistical significance of more than nine standard deviations. The $\bar{B}^0_s \to D^0 K^{*0}$ branching fraction is measured relative to that of $\bar{B}^0 \to D^0 \rho^0$: $\frac{{\cal B}(\bar{B}^0_s \to D^0 K^{*0})}{{\cal B}(\bar{B}^0 \to D^0 \rho^0)} = 1.48 \pm 0.34 \pm 0.15 \pm 0.12$, where the first uncertainty is statistical, the second systematic and the third is due to the uncertainty on the ratio of the $B^0$ and $B^0_s$ hadronisation fractions. Commentaires: 10 pages, 3 figures, submitted to Phys. Lett. B (See paper for full list of authors)