Possible three-nucleon force effects in D–P scattering at low energies

We present measurements of the analyzing powers Ay and iT11 for proton–deuteron scattering at Ec.m.=432 keV. Calculations using a realistic nucleon-nucleon potential (Argonne V18) are found to underpredict both analyzing powers by ≈40%. The inclusion of the Urbana three-nucleon interaction does not significantly modify the calculated analyzing powers. Due to its short range, it is difficult for this three-nucleon interaction to affect Ay and iT11 at this low energy. The origin of the discrepancy remains an open question.