Bernard Cohen made several contributions to particular areas in nuclear theory, for example demonstrating a previously unrecognized σ × p force acting on nucleons in the nucleus [Ref.24]; its direction is perpendicular to the nucleon momentum and hence cannot be represented by a potential. Other contributions involved symmetry energy [Ref.25], spin-orbit splitting [Ref.26], and neutron-proton interactions [Ref.27] in nuclei.
