X(1835), X(2120) and X(2370) in a flux tube model

TL;DR

This paper models the nonstrange baryonium spectrum using a flux tube approach, successfully describing certain observed states as bound states, but not all, with parameters fixed by baryon properties.

Contribution

It introduces a parameter-free flux tube model with a six-body confinement potential to systematically study baryonium states.

Findings

X(1835) and X(2370) are described as bound states in the model.

X(2120) cannot be explained by the model.

Model parameters are fixed by baryon properties.

Abstract

Nonstrange baryonium spectrum is systematically studied by using the Gaussian expansion method in a flux tube model with the six-body confinement potential. All the model parameters are fixed by baryon properties, so the baryonium calculation is parameter-free. We find that X(1835) and X(2370), which are observed in the radiative decay of $J/\psi$ by BES collaboration, can be described as $N_8\bar{N}_8$ and $\Delta_8\bar{\Delta}_8$ bound states with quantum numbers $I^GJ^{PC}=0^+0^{-+}$, respectively, such bound states should be color confinement resonances with three-dimensional configurations similar to dumbbell, however, X(2120) can not be accommodated in our model.