Spectra and scattering of light lattice nuclei from effective field theory

An effective field theory is used to describe light nuclei, calculated from quantum chromodynamics on a lattice at unphysically large pion masses. The theory is calibrated at leading order to two available data sets on two- and three-body nuclei for two pion masses. At those pion masses we predict the quartet and doublet neutron-deuteron scattering lengths, and the alpha-particle binding energy. For m(pi) = 510 MeV we obtain, respectively, (4)a(nD) = 2.3 +/- 1.3 fm, (2)a(nD) = 2.2 +/- 2.1 fm, and B-alpha = 35 +/- 22 MeV, while for m(pi) = 805 MeV (4)a(nD) = 1.6 +/- 1.3 fm, (2)a(nD) = 0.62 +/- 1.0 fm, and B-alpha = 94 +/- 45 MeV are found. Phillips- and Tjon-like correlations to the triton binding energy are established. We find the theoretical uncertainty in the respective correlation bands to be independent of the pion mass. As a benchmark, we present results for the physical pion mass, using experimental two-body scattering lengths and the triton binding energy as input. Hints of subtle changes in the structure of the triton and alpha particle are discussed.