Ka. Makarov et Vv. Melezhik, 2 SIDES OF THE COIN - THE EFIMOV-EFFECT AND COLLAPSE IN 3-BODY SYSTEMS WITH POINT-LIKE INTERACTIONS .1., Theoretical and mathematical physics, 107(3), 1996, pp. 755-769
Three-body systems with point-like interactions and internal structure
s are considered. A complete classification of these systems is carrie
d out and the conditions for the corresponding energy operators to be
semi-bounded from below are studied.