Newly observed resonance $ X(4685) $: diquark-antidiquark picture

TL;DR

This paper predicts the mass and properties of the newly observed $X(4685)$ resonance using QCD sum rules, supporting its diquark-antidiquark structure and suggesting possible experimental searches for related states.

Contribution

It provides the first QCD sum rule calculation of the $X(4685)$ mass and pole residue, and predicts a hidden-bottom partner state for future experimental verification.

Findings

Mass of $X(4685)$ estimated at 4607 MeV

Predicted hidden-bottom partner around 10604-10924 MeV

Provides theoretical support for diquark-antidiquark structure

Abstract

In this work, the mass and pole residue of $ X(4685) $ state with spin-parity $J^P=1^+$ are computed by the QCD sum rule approaches up to operator dimension seven based on the diquark-antidiquark configuration. For its mass we get $ m_{X_{cs}}= 4607^{+36}_{-22} $ MeV and pole residue $ \lambda_{X_{cs}}= 6.19^{+0.32}_{-0.24}\times 10^{-2}~\mathrm{GeV^5}$, which may be checked via other nonperturbative approaches as well as future experiments. As a by product, the mass of the hidden-bottom partner state of the $ X(4685) $ is extracted to be both around $ m_{X_{bs}}= (10604-10924) $ MeV and $ \lambda_{X_{bs}}= (42.2-53.7)\times 10^{-2}~\mathrm{GeV^5}$, which can be searched in the $\Upsilon \phi $ invariant mass distribution.