Quark mass dependence of pp scattering in isospin 0, 1, and 2 from lattice QCD

Using lattice QCD we extract xx scattering amplitudes with isospin 0, 1, and 2 in low partial-waves at two values of the light quark mass corresponding to mx & SIM; 283 and 330 MeV. We confirm expectations of weak repulsion in isospin-2, and the presence of a narrow p resonance in isospin-1, and study the pion mass dependence of these channels. In isospin-0 we find that the two pion masses considered straddle the point at which the a-transitions from being a stable bound state to being either a virtual bound state or a subthreshold resonance. We discuss the ability of lattice calculations like these to precisely determine the a -pole location when it is a resonance, and propose an approach in which the full complement of amplitudes computed in this paper can be used simultaneously to provide more constraint.