Recent results in chiral effective field theory for the NN system

I describe recent progress towards a theory of the NN force which captures the consequences of QCD's chiral symmetry and the pattern of its breaking, and is formulated as an expansion in a ratio of low and high mass scales, M_{lo}/M_{hi}. This "chiral effective field theory" of the NN system is a firm foundation for explorations of nuclear structure and reactions that are grounded in QCD's low-energy symmetries. While calculations that use a ChiPT expansion for the NN potential have proven very successful, they can only be used with a narrow range of momentum-space cutoffs, which leaves the expansion parameter for observable quantities somewhat murky. Here we seek a truly systematic effective field theory for the NN amplitude, that is manifestly renormalization-group invariant at each order in a demonstrably perturbative expansion.Comment: Invited talk at the 7th International Workshop on Chiral Dynamics, August 6-10, 2012, Jefferson Lab, Newport News, VA. To appear in the proceedings. 12 pages, 5 figure

The nucleon-nucleon system in chiral effective theory

I discuss the conditions under which the application of chiral perturbation theory to the NN potential gives reliable results for NN scattering phase shifts. ChiPT also yields a convergent expansion for the deuteron charge operator. For cutoffs < 1 GeV, this produces precise predictions for deuterium's quadrupole and charge form factors in the range Q^2 < 0.25 GeV^2.Comment: 4 pages, 4 figures. Contribution to Proceedings of "12th International Conference on Meson-Nucleon Physics and the Structure of the Nucleon", Williamsburg, VA, May 31-June 4, 201

Electron-deuteron scattering in a relativistic theory of hadrons

We review a three-dimensional formalism that provides a systematic way to include relativistic effects including relativistic kinematics, the effects of negative-energy states, and the boosts of the two-body system in calculations of two-body bound-states. We then explain how to construct a conserved current within this relativistic three-dimensional approach. This general theoretical framework is specifically applied to electron-deuteron scattering both in impulse approximation and when the $\rho \pi \gamma$ meson-exchange current is included. The experimentally-measured quantities $A$, $B$, and $T_{20}$ are calculated over the kinematic range that is probed in Jefferson Lab experiments. The role of both negative-energy states and meson retardation appears to be small in the region of interest.Comment: 17 pages, 4 figures, uses BoxedEPS.tex, lamuphys.sty, bibnorm.sty. To appear in the proceedings of the Workshop on Electron-Nucleus Scattering held at the Elba International Physics Center, June 199