Determine the dielectron width of fully-charmed vector tetraquarks

Determine the dielectron width \(\Gamma_{ee}\) of fully-charmed vector tetraquark states, for which no direct experimental information is currently available, in order to establish the corresponding \(e^+e^-\to T_{4c}\to\eta_c J/\psi\) production cross section.

Background

The projected sensitivity of the STCF search depends directly on the dielectron width Γee\Gamma_{ee} of the fully-charmed vector tetraquark candidate T4cT_{4c}. The paper treats this quantity as unresolved and evaluates three benchmark values, $0.25$, $0.5$, and $1$ eV, because the production cross section is proportional to Γee\Gamma_{ee}.

A direct determination of Γee\Gamma_{ee} would therefore convert the feasibility study's benchmark assumptions into experimentally grounded predictions and improve the interpretation of any observed ηcJ/ψ\eta_cJ/\psi resonance.

References

Because the signal cross section is governed by the still-uncertain dielectron width \Gamma_{ee}, we consider three benchmark hypotheses, \Gamma_{ee}=0.25, 0.5, 1~\mathrm{eV}.

— Feasibility Study of $e^+e^-\to η_cJ/ψ$ Production and Fully-Charmed Tetraquark Searches at STCF  (2609.25870 - Dong et al., 22 Sep 2026) in Abstract; Section 3, Methodology and Pseudo-data