Executive Summary : | Efimov universality can play a crucial role in the search and identification of an entire class of exotic neutron-rich three-particle nuclei, as well as hypernuclei, categorized as halo-nuclei. These are characterized by shallow bound states with large two-particle scattering lengths among the bound constituents. Despite the large repository of works in this regard, the feasibility of Efimovian strange or charm mesonic halo systems remains elusive as large. Various potential models in the past have hinted the existence of a strongly attractive K-bar N interaction leading to a variety of exotic (anti-) kaonic nuclear clusters. The recent discovery of exotic open charm and bottom XYX hadronic molecules have prompted similar studies in the heavy flavor sectors. Subsequent studies in the charm sector indicate the existence of an DN threshold bound state in the T=0 isospin channel leading to a plausible DNN bound three-body state in J=0, T=1/2 channel. But the underlying character of such states has been largely difficult to assess given the ad hoc model assumptions which are often conflicting between different models. The absence of universality in the models have prompted the use of effective field theoretical (EFT) frameworks to determine the universal character of few-body systems. In particular, EFT have emerged as an useful computational tool facilitating model-independent studies of two-and three-body bound states and predicting the emergent Efimov character invoking suitable idealizations. As the first pionless EFT study of an exotic charmed nuclei, our work in Ref.[1] investigated the Efimov character of the D⁰nn (J=0, T=3/2) system invoking a zero-coupling limit idealization leading to the absence of decay channels. Using a sharp momentum cut-off regulator in the Faddeev scattering integral equations, Efimov-like states were readily manifested at a low-enough value of the critical cut-off ~40 MeV, in comparison to the EFT hard scale determined by the pion mass. This indicates the feasible prospect of a realistic Efimov-like bound or resonance state. Our previous EFT methodology developed in Refs.[1-2] pave a clear pathway for further investigations to unveil the underlying universal structure of the D⁰nn bound system. To this end, the project proposal aims to formulate an effective quantum mechanical framework by employing momentum space Faddeev techniques for reconstructing the three-body wavefunctions for the S-wave D⁰nn bound system to extract geometrical aspects, such as the matter radii and the two-neutron opening angle. Such structural predictions based on universality could not only shed light on the inherent character of the clustering mechanism, but also provide useful inputs for future lattice QCD simulations for such systems. |