Observation of Bs0→D¯*0ϕ and search for B0→D¯0ϕ decays

Le résumé fourni par la source

The first observation of the ${B}_{s}^{0}\ensuremath{\rightarrow}{\overline{D}}^{*0}\ensuremath{\phi}$ decay is reported, with a significance of more than seven standard deviations, from an analysis of $pp$ collision data corresponding to an integrated luminosity of $3\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$, collected with the LHCb detector at center-of-mass energies of 7 and 8 TeV. The branching fraction is measured relative to that of the topologically similar decay ${B}^{0}\ensuremath{\rightarrow}{\overline{D}}^{0}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ and is found to be $\mathcal{B}({B}_{s}^{0}\ensuremath{\rightarrow}{\overline{D}}^{*0}\ensuremath{\phi})=(3.7\ifmmode\pm\else\textpm\fi{}0.5\ifmmode\pm\else\textpm\fi{}0.3\ifmmode\pm\else\textpm\fi{}0.2)\ifmmode\times\else\texttimes\fi{}1{0}^{\ensuremath{-}5}$, where the first uncertainty is statistical, the second systematic, and the third from the branching fraction of the ${B}^{0}\ensuremath{\rightarrow}{\overline{D}}^{0}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ decay. The fraction of longitudinal polarization in this decay is measured to be ${f}_{\mathrm{L}}=(73\ifmmode\pm\else\textpm\fi{}15\ifmmode\pm\else\textpm\fi{}4)%$. The most precise determination of the branching fraction for the ${B}_{s}^{0}\ensuremath{\rightarrow}{\overline{D}}^{0}\ensuremath{\phi}$ decay is also obtained, $\mathcal{B}({B}_{s}^{0}\ensuremath{\rightarrow}{\overline{D}}^{0}\ensuremath{\phi})=\phantom{\rule{0ex}{0ex}}(3.0\ifmmode\pm\else\textpm\fi{}0.3\ifmmode\pm\else\textpm\fi{}0.2\ifmmode\pm\else\textpm\fi{}0.2)\ifmmode\times\else\texttimes\fi{}1{0}^{\ensuremath{-}5}$. An upper limit, $\mathcal{B}({B}^{0}\ensuremath{\rightarrow}{\overline{D}}^{0}\ensuremath{\phi})<2.0$ $(2.3)\ifmmode\times\else\texttimes\fi{}1{0}^{\ensuremath{-}6}$ at 90% (95%) confidence level is set. A constraint on the $\ensuremath{\omega}\ensuremath{-}\ensuremath{\phi}$ mixing angle $\ensuremath{\delta}$ is set at $|\ensuremath{\delta}|<5.2\ifmmode^\circ\else\textdegree\fi{}$ (5.5\ifmmode^\circ\else\textdegree\fi{}) at 90% (95%) confidence level.

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