New puzzle for many-body systems with random two-body interactions

We continue a series of numerical experiments on many-body systems with random two-body interactions, by examining correlations in ratios in excitation energies of yrast J = 0,2,4,6,8 states. Previous studies, limited only to J = 0,2,4 states, had shown strong correlations in boson systems but not fermion systems. By including J >= 6 states and considering different scatter plots, strong correlations between ratios of yrast excitation energies appear in both boson and fermion systems. Such correlations agree with real nuclear data and include the well-known limits of seniority, vibrations, and rotations.