Universal isoscalar optical-potential parameter for N=Z nuclides

Determine whether a single global complex isoscalar antiproton–nucleon parameter b_0, used with a fixed finite interaction range β in the antineutron–nucleus optical potential, can account for the experimentally measured antineutron scattering lengths of different N=Z nuclides, including carbon-12, silicon-28, and calcium-40.

Background

The paper calculates antineutron–nucleus scattering lengths indirectly from optical potentials originally constrained by antiprotonic-atom data. In the isoscalar approximation, the optical potential is governed by a single complex parameter b_0 and a finite interaction-range parameter β. For N=Z nuclei, the isovector density δρ(r)=ρ_n(r)−ρ_p(r) is small, so the authors argue that the isoscalar potential should provide a useful baseline description.

The proposed test is to measure antineutron scattering lengths for several N=Z nuclides and determine whether one common value of b_0, with fixed β, describes them all. Measuring both the real and imaginary parts is important because they constrain different combinations of the magnitude and phase of b_0 once the nuclear density distribution is fixed.