Few-body systems interacting near the unitarity regime

There have been many studies over the years on few-body systems interacting near the unitarity limit. Notable studies have been extensively researched for systems of bosons, particularly to understand the Efimov effect for three-interacting bosons near s-wave unitarity and its implications for N-boson systems. There have been other interesting systems consisting of interacting fermions like in the BEC-BCS corssover problem and in the study of polaron physics. In our previous work, three and four equal-mass systems in various angular momentum and spin states for different s-wave and p-wave interactions were studied to investigate universal physics when the interactions are tuned near the unitary limit, i.e. when the scattering length or scattering volume approaches infinity [Phys. Rev. A 106, 023304 (2022)]. In this current work, we expand on the previous study using the adiabatic hyperspherical treatment, focusing on N-body systems for N>3 in search of universal physics near the unitarity regime, considering both N=4 and N=5. An interesting system to look at is an impurity embedded in a sea of fermions, which will aid in our understanding of Bose-polaron physics. Furthermore, through a comprehensive analysis of the hyperspherical potential curves for these different systems, information about the long-range dependence can provide insight into various threshold-law behaviors that govern many low-energy processes such as N-body recombination.