Spin correlation coefficient for proton- He3 elastic scattering at 100 MeV

We present the measured spin correlation coefficient Cy,y for p−He3 elastic scattering at 100 MeV at the angles θc.m.=46.9∘–149.2∘ in the center-of-mass system. The Cy,y data and the existing cross section data are compared with rigorous four-nucleon scattering calculations based on realistic nucleon-nucleon potentials. Large differences are seen in the regime around the cross section minimum for both observables. The Δ-isobar effects estimated by the NN+NΔ coupled-channels approach are small for the cross section. Meanwhile, in Cy,y, the Δ-isobar effects improve the agreement with the data. The analysis of the p−He3 elastic scattering amplitudes implies the necessity of three-nucleon forces (3NFs) that enhance the vector components in the amplitudes. The obtained results indicate that the spin correlation coefficient Cy,y expands the knowledge of the nuclear interactions with the Δ isobar or those including 3NFs that are masked in nucleon-deuteron elastic scattering.1 MoreReceived 29 July 2022Accepted 17 October 2022DOI:https://doi.org/10.1103/PhysRevC.106.054002©2022 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasFew-body systemsH & He induced nuclear reactionsNuclear forcesNucleon-nucleon interactionsNuclear Physics