Dimensional Regularization and Nuclear Potentials

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 ($\delta$-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.Comment: 7 pages, latex, 2 figures -- To appear in Int. J. Mod. Phys. E -- epsfig.sty require

Twenty-Five Years of Progress in the Three-Nucleon Problem

Twenty-five years ago the International Few-Body Conference was held in Quebec City. It became very clear at that meeting that the theoretical situation concerning the He3 and H3 ground states was confused. A lack of computational power prevented converged brute-force solutions of the Faddeev or Schroedinger equations, both for bound and continuum states of the three-nucleon systems. Pushed by experimental programs at Bates and elsewhere and facilitated by the rapid growth of computational power, converged solutions were finally achieved about a decade later. Twenty-five years ago the first three-nucleon force based on chiral-symmetry considerations was produced. Since then this symmetry has been our guiding principle in constructing three-nucleon forces and, more recently, nucleon-nucleon forces. We are finally nearing an understanding of the common ingredients used in constructing both types of forces. I will discuss these and other issues involving the few-nucleon systems and attempt to define the current state-of-the-art.Comment: Invited talk at Bates25 Symposium, MIT, November 3-5, 1999 - 13 pages, latex, 8 figures - To appear in AIP Conference Proceedings - epsfig.sty and aipproc.sty require

Few-Body Physics -- Then and Now

A summary of the XIV\underline{th} International Conference on Few-body Problems In Physics is given, with an emphasis on the important problems solved recently and the prognosis for the future of the field. Personal remarks and ``homework'' problem assignments are made.Comment: 17 pages, 1 fig., LA-UR-94-213

Three-Nucleon Forces for the New Millennium

Most nuclear physics ranges from insensitive to relatively insensitive to many-nucleon forces. The dominant ingredient in calculations of nuclear properties is the nucleon-nucleon potential. Three-nucleon forces nevertheless play an important role in nuclear physics because of the great precision of modern calculational methods for systems of relatively few nucleons. We explore the reasons why many-body forces are weak in nuclei by using a classification scheme for such forces that is based on dimensional power counting, which is used to organize chiral perturbation theory. An assessment will be made of how close we are to a ``standard'' three-nucleon force. Recent advances in determining the significance of three-nucleon forces will also be discussed.Comment: Invited talk presented at XVIth International Conference on Few-Body Problems in Physics, Taipei, Taiwan, March 6-10, 2000. -- 9 pages, latex, 3 figures -- To appear in Nuclear Physics A -- fleqn.sty, espcrc1.sty, and epsfig.sty require

The Structure of Light Nuclei and Its Effect on Precise Atomic Measurements

This review consists of three parts: (a) what every atomic physicist needs to know about the physics of light nuclei; (b) what nuclear physicists can do for atomic physics; (c) what atomic physicists can do for nuclear physics. A brief qualitative overview of the nuclear force and calculational techniques for light nuclei will be presented, with an emphasis on debunking myths and on recent progress in the field. Nuclear quantities that affect precise atomic measurements will be discussed, together with their current theoretical and experimental status. The final topic will be a discussion of those atomic measurements that would be useful to nuclear physics, and nuclear calculations that would improve our understanding of existing atomic data.Comment: 24 pages, latex, 6 figures, svmult.cls required -- index at back To appear in "Precision Physics of Simple Atomic Systems," ed. by S. Karshenboim, (Springer-Verlag, Berlin, in preparation

Boundary Conditions for Three-Body Scattering in Configuration Space

The asymptotic behavior of three-body scattering wave functions in configuration space is studied by considering a model equation that has the same asymptotic form as the Faddeev equations. Boundary conditions for the wave function are derived, and their validity is verified by numerical calculations. It is shown that these boundary conditions for the partial differential equation can be used to obtain accurate numerical solutions for the wave function.Comment: 25 pages, revtex, 9 figures. Submitted to Phys. Rev. C, epsfig.sty require

Comment on "Constraints on proton structure from precision atomic physics measurements"

We strongly disagree with the procedure used in a recent paper to extract the Zemach moment for hydrogen.Comment: 1 page, 2 figures, revtex - submitted to Physical Review Letter