Searches for $B^0\to K^{+}{\pi }^{-}{\tau }^{+}{\tau }^{-}$ and $B_s^0\to K^{+}{K}^{-}{\tau }^{+}{\tau }^{-}$ decays

Abstract

The first searches for $B^0\to K^{+}{\pi }^{-}{\tau }^{+}{\tau }^{-}$ and $B_s^0\to K^{+}{K}^{-}{\tau }^{+}{\tau }^{-}$ decays at the LHCb experiment are conducted with $pp$ collision data corresponding to an integrated luminosity of $5.4{\text{ fb}}^{-1}$. The tau leptons are reconstructed using the ${\tau }^{+}\to {\mu }^{+}{\overline{\nu }}_{\tau }{\nu }_{\mu }$ decay and the results are presented in bins of $K^{+}{\pi }^{-}$ or $K^{+}{K}^{-}$ mass. No signal is observed and upper limits are set on the branching fractions. The searches result in the first upper limits for $B^0\to K^{+}{\pi }^{-}{\tau }^{+}{\tau }^{-}$ decays outside the $K^{\ast }(892{)}^0$ region in $K^{+}{\pi }^{-}$ mass and the first limits for $B_s^0\to K^{+}{K}^{-}{\tau }^{+}{\tau }^{-}$ decays. The searches are recast into limits on the decays $B^0\to K^{\ast }(892{)}^0{\tau }^{+}{\tau }^{-}$ and $B_s^0\to \varphi (1020){\tau }^{+}{\tau }^{-}$, yielding $2.8\times 10^{-4}$ ($2.5\times 10^{-4}$) and $4.7\times 10^{-4}$ ($4.1\times 10^{-4}$) at the $95\%$ ($90\%$) confidence level, respectively. For the decay $B^0\to K^{\ast }(892{)}^0{\tau }^{+}{\tau }^{-}$, this result improves on the current best upper limit by an order of magnitude.

arXiv commentAll figures and tables, along with any supplementary material and additional information, are available at https://lbfence.cern.ch/alcm/public/analysis/full-details/4479 (LHCb public pages)

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