Adiabatic hyperspherical study of the helium trimer

The adiabatic hyperspherical method is used to investigate the spectrum of the helium trimer and to explore effects on the spectrum of varying the helium masses as well as the interaction strength. When a realistic helium dimer potential is adopted, only two isotopic combinations are observed to have three-body bound states: ${}_{}{}^4{}_{}{}^{}\mathrm{He}_3^{}{}_{}{}^{}$ and ${}_{}{}^4{}_{}{}^{}\mathrm{He}_2^3{}_{}{}^{}$He. By artificially adjusting the dimer potential, we also determine the range of interaction strengths for which halo states can result. The existence of Efimov states for both physical and unphysical systems is also examined. © 1996 American Institute of Physics.