Observation of $J/\psi\phi$ structures consistent with exotic states from amplitude analysis of $B^+\to J/\psi \phi K^+$ decays

TL;DR

This paper reports the first comprehensive amplitude analysis of the decay $B^+ o J/\, \, $ with detailed quantum number determination, revealing four significant $J/\, \, $ structures, including a broad state near 4140 MeV.

Contribution

It introduces the first full amplitude analysis of this decay mode, identifying multiple exotic-like structures in the $J/\, \, $ mass spectrum with quantum number assignments.

Findings

Four $J/\, \, $ structures observed with >5 sigma significance.

Quantum numbers of the structures determined with >4 sigma significance.

The lightest structure has a broader width than the previously claimed $X(4140)$.

Abstract

The first full amplitude analysis of $B^+\to J/\psi \phi K^+$ with $J/\psi\to\mu^+\mu^-$, $\phi\to K^+K^-$ decays is performed with a data sample of 3 fb$^{-1}$ of $pp$ collision data collected at $\sqrt{s}=7$ and $8$ TeV with the LHCb detector. The data cannot be described by a model that contains only excited kaon states decaying into $\phi K^+$, and four $J/\psi\phi$ structures are observed, each with significance over $5$ standard deviations. The quantum numbers of these structures are determined with significance of at least $4$ standard deviations. The lightest has mass consistent with, but width much larger than, previous measurements of the claimed $X(4140)$ state.