12C(e,e'pN) measurements of short range correlations in the tensor-to-scalar interaction transition region

High-momentum configurations of nucleon pairs at short-distance are probed using measurements of the C-12(e, e p) and C-12(e, e pN) reactions (where N is either n or p), at high-Q(2) and x(B) > 1.1. The data span a missing-momentum range of 300-1000 MeV/c and are predominantly sensitive to the transition region of the strong nuclear interaction from a Tensor to Scalar interaction. The data are well reproduced by theoretical calculations using the Generalized Contact Formalism with both chiral and phenomenological nucleon-nucleon (NN) interaction models. This agreement suggests that the measured high missing-momentum protons up to 1000 MeV/c predominantly belong to short-ranged correlated (SRC) pairs. The measured C-12(e, e pN)/C-12(e, e p) and C-12(e, e pp)/C-12(e, e pn) cross-section ratios are consistent with a decrease in the fraction of proton-neutron SRC pairs and increase in the fraction of proton-proton SRC pairs with increasing missing momentum. This confirms the transition from an isospin-dependent tensor NN interaction at similar to 400 MeV/c to an isospin-independent scalar interaction at high-momentum around similar to 800 MeV/c as predicted by theoretical calculation. (C) 2021 The Author(s). Published by Elsevier B.V.