The Meson Theory of Nuclear Forces and Nuclear Structure

Abstract

After a historical review, I present the progress in the field of realistic NN potentials that we have seen in recent years. A new generation of very quantitative (high-quality/high-precision) NN potentials has emerged. These potentials will serve as reliable input for microscopic nuclear structure calculations and will allow for a systematic investigation of off-shell effects. The issue of three-nucleon forces is also discussed.

The nuclear spin-orbit force in chiral effective field theories

“…The existence of such a trade-off has been noted in previous studies of the isoscalar tensor coupling in QHD models, but good fits to nuclei were found only with relatively small values of the coupling and thus small M * 0 ≈ 0.6M [18,11]. Furthermore, this coupling is usually taken to be zero in one-boson-exchange potentials [19] or limited to small values due to constraints from free nucleon form factors and the assumption of vector meson dominance [20][21][22][23]. However, as an effective coupling in nuclei, which might absorb higher-order many-body effects at the mean-field level, the isoscalar tensor coupling could be much larger than these constraints dictate and still be of natural size.…”

“…(Note that f v as defined here corresponds to the combination f v /g v typically appearing in one-boson-exchange models [19].) The analog of Eq.…”

“…5, we see that such a limit implies an unimportant change in M * from the results with f v = 0. In one-boson-exchange potentials, the isovector tensor coupling is important, but the isoscalar tensor coupling is usually taken to be zero [19]. On the other hand, without further assumptions, the value of f v in the point-coupling models is not related to the electromagnetic structure of the nucleon and is therefore unconstrained.…”

Interplay between tensor force and deformation in even–even nuclei

“…Besides the requirement to include a tensor term to the bare nucleon-nucleon interaction is supported by some well known experimental data such as the none zero quadrupole moment of the deuteron [1,2,3] or the differential cross section of the p-p scattering. Consequently all the most popular potentials used in the ab-initio approaches as the Paris [4], Bonn [5,6,7] or Argonne [8] potentials get a built-in tensor component. Its impact on the shell structure properties has been studied in a large extent: its contribution to the single particle energies depends on the filling of the shells; it induces correlations which strongly influence the n-p pairs structures in light nuclei [9]; the tensor force enables to get a convenient spectrum in the p-shell [10].…”

The theory of nuclear forces: Is the never-ending story coming to an end?

“…Based upon the Yukawa idea [ 1] and the discovery of the pion, the 1950's became the first period of "pion theories". These, however, resulted in failure-for reasons we understand today: pion dynamics is ruled by chiral symmetry, a constraint that was not realized in the theories of the 1950's.The 1960's and 70's represent the main period for theories that also include heavy mesons ("meson theories") [ 2], but the work on meson models continued all the way into the 1990's when the family of the so-called high-precision NN potentials was developed. This family includes the Nijm-I, Nijm-II, and Reid93 potentials [ 3], the Argonne V 18 [ 4], and the CD-Bonn potential [ 5,6].…”