Measurement and calculation of the polarization transfer parameterKyy′in neutron-deuteron scattering at 15.0, 17.0, 19.0, and 25.8 MeV

The nucleon-to-nucleon polarization transfer parameter $K_y^{y^{\prime }}$ has been measured for the first time in neutron-deuteron scattering, at bombarding energies $E_n=15.0,$ 17.0, 19.0, and 25.8 MeV and scattering angles ${\theta }_{\mathrm{lab}}=50\mathrm{}°$ and 80°. The results are compared with rigorous, fully charge-dependent Faddeev calculations using the most recent realistic, phase-equivalent nucleon-nucleon interactions and the Tucson-Melbourne three-nucleon force (TM 3NF). Good agreement between theory and experiment was found at 50° where all potential models predict nearly the same value for $K_y^{y^{\prime }}.$ At 80°, the pure $\mathrm{NN}$ force predictions are spread due to their different $D$-state probabilities for the deuteron. When the TM 3NF is included, with the cutoff parameter in the strong form factors fitted to the experimental triton binding energy separately for each of the $\mathrm{NN}$ interactions, the different force predictions are shifted in such a way that they essentially agree with each other. This means that $K_y^{y^{\prime }}$ scales with the triton binding energy. At 50°, the 3NF causes only a small decrease in the theoretical predictions, which still are close to the experimental values. In the minimum around 80°, the inclusion of the 3NF leads to a more pronounced decrease of $K_y^{y^{\prime }}$ so that the theory now underestimates the data by about 10%. A comparison of our $n-d$ data with existing $p-d$ data indicates appreciable Coulomb force effects in the region of the minimum of $K_y^{y^{\prime }}.$