Branching fraction measurements of $B^{0}_{(s)} \rightarrow J\mskip -3mu/\mskip -2mu\psi\mskip 2mu K_{S}^{0} h^{+} h^{(\prime)-}$ decays

This thesis presents the branching fractions measurements of $B^{0}_{(s)} \rightarrow J\mskip -3mu/\mskip -2mu\psi\mskip 2mu K_{S}^{0} h^{+} h^{(\prime)-}$ ($h^{(\prime)} = K, \pi$) decays, corresponding to an integrated luminosity of $1.0 \mbox{fb}^{-1}$ of data recorded at a centre-of-mass energy of $\sqrt{s}=7 \mathrm{\,Te\kern -0.1em V}$ collected with the LHCb detector at CERN Large Hadron Collider (LHC) during 2011. The first observation of the $B^{0}_{s} \rightarrow J\mskip -3mu/\mskip -2mu\psi\mskip 2mu K_{S}^{0} K^{\pm} \pi^{\mp}$ decay is reported, with a significance greater than 10 standard deviations. The $B^{0} \rightarrow J\mskip -3mu/\mskip -2mu\psi\mskip 2mu K_{S}^{0} K^{+} K^{-}$ decay is also observed for the first time. The branching fraction of $B^{0} \rightarrow J\mskip -3mu/\mskip -2mu\psi\mskip 2mu K_{S}^{0} \pi^{+} \pi^{-}$ is determined, to significantly better precision than previous measurements, using $B^{0} \rightarrow J\mskip -3mu/\mskip -2mu\psi\mskip 2mu K_{S}^{0}$ as a normalisation channel. Branching fractions and upper limits of the other $B^{0}_{(s)} \rightarrow J\mskip -3mu/\mskip -2mu\psi\mskip 2mu K_{S}^{0} h^{+} h^{(\prime)-}$ modes are determined relative to that of the $B^{0} \rightarrow J\mskip -3mu/\mskip -2mu\psi\mskip 2mu K_{S}^{0} \pi^{+} \pi^{-}$ decay.