Exotic vector charmonium and its leptonic decay width

TL;DR

This paper introduces a new hybrid-like vector charmonium state with a mass around 4.33 GeV, exploring its properties and potential relation to the X(4260), and estimates its leptonic decay width to be very small.

Contribution

It proposes novel hybrid-like interpolating operators and identifies a heavy vector charmonium state with unique coupling properties and a very small leptonic decay width.

Findings

Identified a 4.33 GeV vector charmonium-like state.

State has weak coupling to quark bilinear operators.

Estimated leptonic decay width to be less than 10% of J/ψ.

Abstract

We propose a novel type of interpolating field operators, which manifests the hybrid-like configuration that the charm quark-antiquark pair recoils against gluonic degrees of freedom. A heavy vector charmonium-like state with a mass of $4.33(2)\,{\rm GeV}$ is disentangled from the conventional charmonium states in the quenched approximation. This state has affinity for the hybrid-like operators but couples less to the relevant quark bilinear operator. We also try to extract its leptonic decay constant and give a tentative upper limit that it is less than one tenth of that of $J/\psi$, which corresponds to a leptonic decay width about dozens of eV. The connection of this state with $X(4260)$ is also discussed.