Search for $D^{\ast }(2007{)}^0\to \hat{I}{¼}^{+}\hat{I}{¼}^{-}$ in $B^{-}\to \ddot{I}{€}^{-}\hat{I}{¼}^{+}\hat{I}{¼}^{-}$ decays

Abstract

The very rare $D^{\ast }(2007{)}^0\to \hat{I}{¼}^{+}\hat{I}{¼}^{-}$ decay is searched for by analysing $B^{-}\to \ddot{I}{€}^{-}\hat{I}{¼}^{+}\hat{I}{¼}^{-}$ decays. The analysis uses a sample of beauty mesons produced in proton-proton collisions collected with the LHCb detector between 2011 and 2018, corresponding to an integrated luminosity of 9 fb${}^{-1}$. The signal signature corresponds to simultaneous peaks in the $\hat{I}{¼}^{+}\hat{I}{¼}^{-}$ and $\ddot{I}{€}^{-}\hat{I}{¼}^{+}\hat{I}{¼}^{-}$ invariant masses. No evidence for an excess of events over background is observed and an upper limit is set on the branching fraction of the decay at $\mathcal{B}(D^{\ast }(2007{)}^0\to \hat{I}{¼}^{+}\hat{I}{¼}^{-})<2.6\times 10^{-8}$ at $90\%$ confidence level. This is the first limit on the branching fraction of $D^{\ast }(2007{)}^0\to \hat{I}{¼}^{+}\hat{I}{¼}^{-}$ decays and the most stringent limit on $D^{\ast }(2007{)}^0$ decays to leptonic final states. The analysis is the first search for a rare charm-meson decay exploiting production via beauty decays.

All figures and tables, along with machine-readable versions and any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2023-004.html (LHCb public pages)