  The protons and neutrons in a nucleus can form strongly correlated nucleon
pairs. Scattering experiments, where a proton is knocked-out of the nucleus
with high momentum transfer and high missing momentum, show that in 12C the
neutron-proton pairs are nearly twenty times as prevalent as proton-proton
pairs and, by inference, neutron-neutron pairs. This difference between the
types of pairs is due to the nature of the strong force and has implications
for understanding cold dense nuclear systems such as neutron stars.
