Amplitude analysis of $B^+\to J/\psi \phi K^+$ decays

TL;DR

This paper presents the first comprehensive amplitude analysis of the decay $B^+ o J/ heta o heta$ with data from the LHCb detector, revealing four significant $J/ heta$ structures and new insights into kaon excitations.

Contribution

It introduces the first full amplitude analysis of this decay mode, identifying four $J/ heta$ structures and the first observation of the $K^{*}(1680)^+ o heta$ transition, expanding understanding of hadronic states.

Findings

Four $J/ heta$ structures observed with >5σ significance.

Quantum numbers of structures determined with >4σ significance.

First observation of $K^{*}(1680)^+ o heta$ transition.

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. The model includes significant contributions from a number of expected kaon excitations, including the first observation of the $K^{*}(1680)^+\to\phi K^+$ transition.