“…In the low-energy limit, the contact potential is a good approximation for any short-range interaction and its usage provides a universal, i. e., independent of the potential form, description of the dynamics [23,26,34,35,36,37]. More specifically, it is assumed that one particle interacts with the other two via an attractive contact interac-tion of strength λ < 0 while the sign of the interaction strength λ 1 for the identical particles is arbitrary.…”