Amplitude analysis of $B^0 \rightarrow η_c(1S) K^+ π^-$ decays

Abstract: An amplitude analysis of the $$B⁰ \rightarrow \eta_{c}(1S) K⁺ \pi^-$$ decays with $\eta_{c}(1S) \to p \bar{p}$ is performed using a sample corresponding to an integrated luminosity of 9$\text{fb}<sup>{-1}$ 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 $K<sup>{0\star}$ 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 $$B⁰ \rightarrow \eta_{c}(1S) K⁺ \pi^-$$ decays is measured to be \begin{align*} \mathcal{B}(B^0 \rightarrow \eta_{c}(1S) K^+ \pi^- ) = (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.