Diffusion Monte Carlo study of deuteron-like fully light hexaquarks

We perform a Diffusion Monte Carlo study of fully light hexaquark containing three $u$ quarks and three $d$ quarks within a constituent-quark model. Both compact and baryon–baryon-like arrangements were considered separately. All compact hexaquark configurations are found well above their corresponding baryon–baryon thresholds, suggesting that deeply bound compact six-quark states are not favored in the light-quark sector within this model. By contrast, several dibaryon-like configurations lie close, but above, to the $NN$, $N\mathrm{\Delta }$, and $\mathrm{\Delta }\mathrm{\Delta }$ thresholds and show spatial structures compatible with molecular states. One configuration exhibits two well-defined nucleon-like subclusters separated by several femtometers, closely resembling the spatial structure of the deuteron, although its calculated energy remains slightly above the corresponding threshold.