2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/37542Using a data sample of 101.8 fb collected by the Belle detector at the KEKB asymmetric energy e+ e- collider, we confirm our published observation of e+ e- -> J/psi eta_c and find no evidence for the process e+ e- -> J/psi J/psi. The latter process was suggested as means to explain the large discrepancy between the published Belle result and theoretical predictions.6 pages, 1 figure, 1 tableHigh Energy Physics - Experimenttext