The decay $B^0to psi(2S) K^+pi^-$ is analyzed using $rm 3~fb^{-1}$ of $pp$ collision data collected with the LHCb detector. A model-independent description of the $psi(2S) pi$ mass spectrum is obtained, using as input the $Kpi$ mass spectrum and angular distribution derived directly from data, without requiring a theoretical description of resonance shapes or their interference. The hypothesis that the $psi(2S)pi$ mass spectrum can be described in terms of $Kpi$ reflections alone is rejected with more than 8$sigma$ significance. This provides confirmation, in a model-independent way, of the need for an additional resonant component in the mass region of the $Z(4430)^-$ exotic state.
Download