# Model-independent observation of exotic contributions to $B^0\to J/\psi K^+\pi^-$ decays

## TL;DR

This study performs a model-independent angular analysis of B0 decays to J/psi, K+, and pi-, revealing significant exotic contributions beyond known K* resonances, with potential new structures near 4200 and 4600 MeV.

## Contribution

It introduces a minimal-assumption, model-independent method to detect exotic contributions in B0 decay angular distributions, challenging the K* resonance-only hypothesis.

## Key findings

- Rejection of the K* resonance-only hypothesis with high significance.
- Evidence of exotic contributions in B0 decay channels.
- Identification of potential new structures near 4200 and 4600 MeV.

## Abstract

An angular analysis of $B^0\to J/\psi K^+\pi^-$ decays is performed, using proton-proton collision data corresponding to an integrated luminosity of 3~${\rm fb}^{-1}$ collected with the LHCb detector. The $m(K^+\pi^-)$ spectrum is divided into fine bins. In each $m(K^+\pi^-)$ bin, the hypothesis that the three-dimensional angular distribution can be described by structures induced only by $K^\ast$ resonances is examined, making minimal assumptions about the $K^+\pi^-$ system. The data reject the $K^\ast$-only hypothesis with a large significance, implying the observation of exotic contributions in a model-independent fashion. Inspection of the $m(J/\psi\pi^-)$ versus $m(K^+\pi^-)$ plane suggests structures near $m(J/\psi\pi^-)=4200$~MeV and 4600~MeV.