Recent Progress in the Theory of Nuclear Forces

Abstract

During the past two decades, it has been demonstrated that chiral effective field theory represents a powerful tool to deal with nuclear forces in a systematic and model-independent way. Two-, three-, and four-nucleon forces have been derived up to next-to-next-to-next-to-leading order (N 3 LO) and (partially) applied in nuclear few-and many-body systems-with, in general, a good deal of success. This may suggest that we are finally done with the nuclear force problem; but that would be too optimistic. There are still some pretty basic open issues that have been swept under rug and, finally, need our full attention, like the proper renormalization of the twonucleon potential. Moreover, the order-by-order convergence of the many-body force contributions is at best obscure at this time.

Study of the charge dependence of the pion–nucleon coupling constant on the basis of data on low-energy nucleon–nucleon interactions

“…Hence, within the framework of the discussed model, the charge independence breaking of nuclear forces is fully explained by the mass difference between the charged and neutral pions and by the mass difference, also present, between the neutron and the proton, the latter giving some minor contribution. In contrast with this, only ∼50% of the experimental difference ∆a expt CIB (37) was explained by the mass difference between the charged and neutral pions in earlier works see [2,22,23,47,48]. 4.…”

“…and has been considered earlier in one form or another in a number of papers [2,19,[21][22][23]. The relation…”

“…Thus, the proposed hypothesis is generally selfconsistent and consistent with the experimental data and the standard classical meson model of Yukawa alike. On the whole, it should be particularly emphasized that the hypothesis that charge independence breaking of nuclear forces in the nucleon-nucleon system has its origin mainly in the difference of the masses of charged and neutral pions is a very long-standing assumption of nuclear physics with a fairly rich history and rationale [2,22,23]. Important combinations of elementary constants (1) are pion-nucleon coupling constants, which characterize the force of the nuclear interaction between two nucleons and can be generally defined as follows [1,3]…”

Microscopic three-cluster study of light exotic nuclei

“…For weakly bound nuclei, the properties are sensitive to the long-range part of the wave function, and therefore to the binding energies. With M = 0.7750, 0.6119, 0.5945 and 0.6177, I reproduce the experimental two-neutron separation energies S 2n of 11 Li, 14 Be, 15 In Fig. 2, I present the convergence of the ground-state energies with the maximum hypermomentum K max .…”

Few-Baryon Interactions from Lattice QCD

“…In Urbana/Illinois models, on the other hand, a repulsive 3NF component at short distance is explicitly introduced in a purely phenomenological way [13]. Recently, an approach based on the chiral effective field theory (χEFT) is also developing [14,15], and found to be useful to classify and parametrize the two-, three-and more-nucleon forces. The χEFT-3NF contains not only pion exchange terms but also short range terms.…”