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

Abstract High-momentum configurations of nucleon pairs at short-distance are probed using measurements of the 12C ( e , e ′ p ) and 12C ( e , e ′ p N ) 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 12C ( e , e ′ p N ) / 12C ( e , e ′ p ) and 12C ( e , e ′ p p ) / 12C ( e , e ′ p n ) 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 ∼400 MeV/c to an isospin-independent scalar interaction at high-momentum around ∼800 MeV/c as predicted by theoretical calculation.