Speaker: Wayne Polyzou (University of Iowa) Title: The three-nucleon problem in Poincar\'e invariant quantum mechanics Abstract: I discuss a formulation of the three-nucleon problem that is suitable for constructing realistic models of scattering reactions with beam energies in the few GeV range. Scattering at these energies requires a Poincar\'e invariant quantum treatment. Since the dynamics at these energies is dominated by a finite number of degrees of freedom, it is possible to model the dynamics using an exact unitary representation of the Poincar\'e group on a few-particle Hilbert space. For the three-nucleon case this representation can be constructed to have cluster properties and satisfy a spectral condition. I show how high-precision NN interactions, like AV18 or CD-Bonn, can be reinterpreted as generating exact two-body unitary representations of the Poincar\'e group that fit experimental two-body scattering data and how cluster separability determines the structure of the three-body dynamics up to three-body interactions. Low-energy calculations using these realistic interactions illustrate the difference between Galilean symmetric and Poincar\'e symmetric calculations of the triton binding energy and the polarization observable $A_y$. Scattering calculations up to 2 GeV, using a Malfliet-Tjon interaction, are used to test the convergence of the multiple scattering series and determine regions of the three-body phase space which are sensitive to differences in the relativistic and non-relativistic treatment. Exclusive breakup experiments at 508 MeV are consistent with the predictions of this relativistic model.