First observation of the decay $D^0\to K^{-}\ddot{I}{€}^{+}\hat{I}{¼}^{+}\hat{I}{¼}^{-}$ in the $\ddot{I}{}^0$-$\ddot{I}‰$ region of the dimuon mass spectrum

Abstract

A study of the decay $D^0\to K^{-}\ddot{I}{€}^{+}\hat{I}{¼}^{+}\hat{I}{¼}^{-}$ is performed using data collected by the LHCb detector in proton-proton collisions at a centre-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 2.0 fb${}^{-1}$. Decay candidates with muon pairs that have an invariant mass in the range 675--875 MeV$/c^2$ are considered. This region is dominated by the $\ddot{I}{}^0$ and $\ddot{I}‰$ resonances. The branching fraction in this range is measured to be $\mathcal{B}$($D^0\to K^{-}\ddot{I}{€}^{+}\hat{I}{¼}^{+}\hat{I}{¼}^{-}$) = $(4.17\pm 0.12(stat)\pm 0.40(syst))\times 10^{-6}$. This is the first observation of the decay $D^0\to K^{-}\ddot{I}{€}^{+}\hat{I}{¼}^{+}\hat{I}{¼}^{-}$. Its branching fraction is consistent with the value expected in the Standard Model.

21 pages, 3 figures. All figures and tables, along with any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2015-043.html