Relativistic effects in three-body bound states

We formulate relativistic and nonrelativistic two-particle dynamics in such a manner that the two-body binding energies are the same for both. We then formulate and solve the relativistic Faddeev equations for a simple s-wave potential (Malfliet-Tjon V). The relativistic effects are small (about 3%) and reduce the three-body binding energy. The expectation value of the relativistic energy operator with the nonrelativistic wave function is a fairly good approximation, but approximate expressions involving expansions in powers of the momentum are shown to be quite unreliable.