A. Lande

Semi-phenomenological fits to nucleon electromagnetic form factors

Several theoretically interesting forms of the nucleon EM form factor have been considered and found to provide quantitative descriptions of available data with as few as three adjustable parameters.

PION EXCHANGE CURRENTS IN ELASTIC ELECTRON DEUTERON SCATTERING

The effects of pion-exchange pari and recoil currents on the electromagnetic form factors of the deuteron are calculated. Both exchange currents give significant contributions to the charge form factor and, despite some cancellation, their net effect is appreciable for q2 ⩾ 10 fm−2.

EULER-LAGRANGE EQUATIONS AND HYPERNETTED CHAIN CALCULATIONS OF BOSON MATTER

Abstract The use of two-body distribution functions which minimize the HNC approximation to the Jackson-Feenberg energy of boson matter is shown to lead to convenient expressions for the calculation of ∂g ∂ρ , pressure and compressibility. Study of the Pandharipande-Bethe energy of boson matter does not reveal a minimum and raises questions regarding the utility of this energy functional.

QUARK-LIKE MODEL OF HIGH-DENSITY MATTER

Abstract High-density matter is discussed in a quark-like model with integrally charged quarks and massless gluons. It is qualitatively shown that a baryon solid phase may develop at ρ ≈ 2–3 times nuclear matter density.

Strong interaction effects in antiprotonic atoms

We investigate the extent to which antiprotonic atoms provide information on the nucleon-antinucleon interaction.

ACCURATE VARIATIONAL FORMS FOR MULTISKYRMION CONFIGURATIONS

Abstract Simple variational forms are suggested for the fields of a single skyrmion on a hypersphere, S 3 ( L ), and of a face-centered cubic array of skyrmions in flat space, R 3 . The resulting energies are accurate at the level of 0.2%. These approximate field configurations provide a useful alternative to brute-force solutions of the corresponding Euler equations.

Finite range effects in pionic atoms

Finite range effects are shown to be important in the derivation of the π-nucleus optical potential.

CROSSING-SYMMETRIC RINGS, LADDERS, AND EXCHANGES

A new approach is used in the description of fermion and boson systems at zero or finite temperature. We generalize the familiar ladder and chaining operations to construct a crossing-symmetric approximation to the two-particle vertex from the bare interaction. The explicit rules for this construction are given in terms of Feynman propagators. The high level of symmetry of the vertex simplifies the theory. In one form, the structure appears as a generalization of parquet diagrams. The energy, self-energy, and vertex satisfy a number of consistency relations.

PARQUET THEORY: THE DIAGRAMS

The summation of parquet diagrams provides an interesting and powerful approach to many-body theory. In this paper, we present several results on the diagrammatic structure of parquet theory. In comparison with previous diagrammatic discussions at this series of workshop[l] or elsewhere [2,3], this paper will derive the final form of the parquet equations (a new result) using simpler methods than the earlier work. The presentation will also be self-contained. As an illustration of the power of the present approach, we also derive the equations which would form the starting point for three-body parquet. Ultimately, we feel that the three-body parquet will be useful in obtaining more accurate results in physical systems, as well as being intimately related to the generation of better vertex approximations following Baym and Kadanoff[4] and Baym[5]. While the discussion here is self-contained, it is presented solely in terms of the diagrammatic structure. There is certainly much more to doing parquet theory than knowing the diagrams, and these other considerations will be discussed in the final section.

Fermion Parquet Equations

The parquet approach to many-body theory focuses on the effective interaction and expresses it in terms of a sum of a large and physically interesting class of Feynman diagrams.