Amplitude analysis of $B^0\to {\eta }_c(1S)K^{+}{\pi }^{-}$ decays

An amplitude analysis of the $B^0\to {\eta }_c(1S)K^{+}{\pi }^{-}$ decays with ${\eta }_c(1S)\to p\bar{p}$ is performed using a sample corresponding to an integrated luminosity of 9${\text{fb}}^{-1}$ of $pp$ collision data collected by the LHCb detector at centre-of-mass energies of $\sqrt{s}$ = 7, 8 and 13TeV. The data are described with a model including only intermediate contributions from known $K^{0\star }$ resonances. Evidence for an exotic resonance in the ${\eta }_c(1S){\pi }^{-}$ system, reported in a previous analysis of this decay channel, is not confirmed. The inclusive branching fraction of the $B^0\to {\eta }_c(1S)K^{+}{\pi }^{-}$ decays is measured to be \begin{align*} $\mathcal{B}$(B^0 \rightarrow η_{c}(1S) K^+ π^- ) = (5.82 \pm 0.20 \pm 0.23 \pm 0.55) \times 10^{-4}, \end{align*} where the first uncertainty is statistical, the second systematic, and the third arises from the limited knowledge of external branching fractions.