Testing nucleonic forces with three nucleon reactions Original Research Article

Results on nucleon-deuteron (Nd) elastic scattering and deuteron breakup below the pion production threshold are discussed emphasizing the need for a three-nucleon force (3NF). Precise solutions of the three-nucleon (3N) Faddeev equations with realistic (semi)phenomenological nucleon-nucleon (NN) potentials alone are insufficient to describe the data. Results involving in addition standard 3NF models like the 2π-exchange TM99 force are presented, which, however, are usually insufficient as well. Relativistic effects turn out to be small. These two observations point to the need of short range 3NF components. Chiral perturbation theory (χPT) provides 3NFʹs which go beyond the 2π-exchange including a one – π-exchange-contact force and a pure 3N-contact force at the lowest order of their occurrence. Their application at the higher energies yields results which are qualitatively and quantitatively different from the results of the standard NN and 3NF models. Though somewhat stretched beyond their proper domain of applicability of that type of forces this supports the conclusion of an increased importance of short range 3NFʹs at those higher energies. The consistent χPT forces carried to higher orders can be expected to establish the final form of the nuclear Hamiltonian.