appreciably the discrepancy in A$_{y}$ and iT 11 . However it gives a slightly worse description of the central minimum of T 21 . The other two models do not improve the description of the observables, compared always to the original AV18+URIX. The modified TM’ model gives similar results though iT 11 is slightly worse whereas the results with the modified URIX model are definitely worse than the original model. The fact that for each model the A$_{y}$ and iT 11 predictions lie in a narrow band, indicates a connection between the short-range structure of the TNF and the polarization observables at low energies. From the analysis we can conclude that the smoother form of the y ( r ), T ( r ) and Z 0 ( r ) functions of the N2LOL potential are preferable. To be noticed that the TM’ and URIX models do not include a D - term. An extended analysis of these two models including it, will allow for a more stringent conclusion about the short-range structure of the TNF models. Preliminary studies in this direction are underway. Finally, at the end of Sec. III, we have analyzed the $^{4}$P$_{J}$ phase-shift parameters. The overall attractive character of the TNF makes larger the $^{4}$P 1 / 2 and $^{4}$P 5 / 2 parameters, com- pared to the ones obtained using a NN force alone, and has little effect on $^{4}$P 5 / 2 . The mixing parameter ϵ 3 / 2 − is larger too. Depending on the relative increase of these parameters, the description of A$_{y}$ and iT 11 can improve, as in the case of the N2LOL model, but not the description of the central minimum of T 21 . The spin-isospin structure of the TNF models studied here cannot lower the $^{4}$P 1 / 2 phase-shift which seems to be necessary in order to improve the description of T 21 in the minimum. A different mechanism has to be included in the structure of the TNF, as for example it has been proposed in Ref. [27]. Studies along this line are at present underway. [1] A. Kievsky, M. Viviani, and S. Rosati, Phys. Rev. C 64 , 024002 (2001) [2] S.A. Coon and W. Gl¨ ockle, Phys. Rev. C 23 , 1790 (1981) [3] B.S. Pudliner, V. R. Pandharipande, J. Carlson, and R.B. Wiringa, Phys. Rev. Lett. 74 , 4396 (1995) [4] J.L. Friar, D. H¨ uber, and U. van Kolck, Phys. Rev. C 59 , 53 (1999) [5] S.A. Coon and H.K. Han, Few-Body Syst. 30 , 131 (2001) [6] H.T. Coelho, T.K. Das, and M.R. Robilotta, Phys. Rev. C 28 , 1812 (1983); M.R. Robilotta 18