  For a system of two identical fermions and one distinguishable particle
interacting via a short-range potential with a large s-wave scattering length,
the Efimov trimers and Kartavtsev-Malykh trimers exist in different regimes of
the mass ratio. The Efimov trimers are known to exhibit a discrete scaling
invariance, while the Kartavtsev-Malykh trimers feature a continuous scaling
invariance. We point out that a third type of trimers, "crossover trimers",
exist universally regardless of short-range details of the potential. These
crossover trimers have neither the discrete nor continuous scaling invariance.
We show that the crossover trimers continuously connect the discrete and
continuous scaling regimes as the mass ratio and the scattering length are
varied. We identify the regions for the Kartavtsev-Malykh trimers, Efimov
trimers, crossover trimers, and non-universal trimers as a function of the mass
ratio and the s-wave scattering length by investigating the scaling property
and model-independence of the trimers.
