James Lewis Friar

Electromagnetic corrections to the one-pion-exchange potential

Leading-order electromagnetic loop corrections to the one-pion-exchange potential are computed within the framework of chiral perturbation theory. These corrections generate an effective nucleon-nucleon potential, V{sub {pi}{gamma}} , which supplements the sum of one-pion-exchange potential and the nucleon-nucleon Coulomb potential. This potential is charge dependent and its construction is demonstrated to be gauge invariant. The potential V{sub {pi}{gamma}} has been included in the Nijmegen partial-wave analysis of np data. A particular renormalization scheme is chosen that leads to a negligible change in the {pi}{sup {plus_minus}}NN coupling constant and in the np {sup 1}S{sub 0} scattering length and effective range. {copyright} {ital 1998} {ital The American Physical Society}

Higher-order nuclear-polarizability corrections in atomic hydrogen

Nuclear-polarizability corrections that go beyond unretarded-dipole approximation are calculated analytically for hydrogenic (atomic) S-states. These retardation corrections are evaluated numerically for deuterium and contribute -0.68 kHz, for a total polarization correction of 18.58(7) kHz. Our results are in agreement with one previous numerical calculation, and the retardation corrections completely account for the difference between two previous calculations. The uncertainty in the deuterium polarizability correction is substantially reduced. At the level of 0.01 kHz for deuterium, only three primary nuclear observables contribute: the electric polarizability,

DIMENSIONAL REGULARIZATION AND NUCLEAR POTENTIALS

\alpha_E

Nuclear forces and chiral theories

, the paramagnetic susceptibility,

Assessment of triton potential energy

\beta_M

Few-body physics: Then and now

, and the third Zemach moment,

Non-adiabatic contributions to static two-pion-exchange nuclear potentials

_{(2)}

Leading-order nuclear pi - gamma exchange force.

. Cartesian multipole decomposition of the virtual Compton amplitude and its concomitant gauge sum rules are used in the analysis.

Chiral symmetry in nuclei

It is shown how nucleon-nucleon potentials can be defined in N dimensions, using dimensional regularization to continue amplitudes. This provides an easy way to separate out contact (δ-function) terms arising from renormalization. An example is worked out several ways for the case of two-scalar particles exchanged between nucleons, which involves a very simple loop calculation. This leads to a Feynman-parameterized representation for the nucleon–nucleon potential. Alternately, a dispersion representation can be developed leading to a different, though equivalent, form.

Quartet n - d scattering lengths

Recent successes in ab initio calculations of light nuclei (A=2-6) will be reviewed and correlated with the dynamical consequences of chiral symmetry. The tractability of nuclear physics evinced by these results is evidence for that symmetry. The relative importance of three-nucleon forces, four-nucleon forces, multi-pion exchanges, and relativistic corrections will be discussed in the context of effective field theories and dimensional power counting. Isospin violation in the nuclear force will also be discussed in this context.