Crossover between universal trimers and Efimov trimers

For a system of two identical fermions and one distinguishable particle interacting via a short-range potential with a large $s$-wave scattering length, Efimov trimers [1] and universal trimers [2] exist in different regimes of mass ratio. These trimers have different scaling symmetry: discrete and continuous scaling symmetry. We point out the existence of a third kind of trimers, ``crossover trimers,'' that continuously connect the two regimes as the mass ratio and the scattering length are varied.\\[4pt] [1] V. Efimov, Nucl. Phys. A {\bf 210}, 157 (1973). \\[0pt] [2] O. I. Kartavtsev, and A. V. Malykh, J. Phys. B, {\bf 40}, 1429 (2007).