contact term of three nucleons W TM E (1 , 2 , 3) = W E 0 Z TM 0 ( r 31 ) Z TM 0 ( r 23 ) . (14) This term corresponds to the E -term in Eq. (2), except that, for the sake of simplicity, we have omitted the ( $^{τ}$1 · $^{τ}$2 ) operator. Its strength W E 0 is defined in Eq. (12) and the function Z TM 0 , defined in Eq. (13), is a positive function, therefore, for positive values of c$_{E}$ , the new term is repulsive. We include it in the following analysis of the TM’ potential. The results are shown in Fig. 3 for three values of Λ /m$_{π}$ = 4 , 4 . 8 , 5 . 6. In the left panels the doublet n − d scattering length is given as a function of the parameter b (in units of b 0 ) for different values of the strength c$_{E}$ of the E -term. The box in the panels includes those values compatible with the experimental results. At each point of the curves, the value of the constant d has been varied to reproduce the triton binding energy. For selected values of the parameters inside the box, the predictions for the $^{4}$He binding energy, B ( $^{4}$He), are shown in the right panels. Comparing the left panels in Figs. 2 and 3, the effect of the new term is clear. In Fig. 2 we have observed that using Λ ≥ 4 m$_{π}$ , $^{2}$a$_{nd}$ cannot be well reproduced. Conversely, in Fig. 3, the inclusion of the new term allows for a description of $^{2}$a$_{nd}$ using different values of the cutoff. The values of the parameter b are closer to its original value as Λ increases. Opposite to this, the predictions of B ( $^{4}$He) improves as Λ decreases. For example, considering the case Λ = 4 m$_{π}$ , $^{2}$a$_{nd}$ , B ( $^{3}$H) and B ( $^{4}$He) are well reproduced with b = 3 . 2 b 0 , d = 6 . 2 d 0 and c$_{E}$ = 1. With Λ = 4 . 8 m$_{π}$ the set of parameters that gives the best description of the three quantities is b = 1 . 5 b 0 , d = 4 . 5 d 0 and c$_{E}$ = 1 . 6. And with Λ = 5 . 6 m$_{π}$ they are b = 0 . 8 b 0 , d = 3 d 0 and c$_{E}$ = 2. Their different contributions to the triton binding energy are given in Table II, where we report the mean values of the kinetic energy and the NN potential energy as well as the mean values of the attractive part of the TNF, V$_{A}$ (3 N ), corresponding to the sum of the a , b and d -terms, and the repulsive part, V$_{R}$ (3 N ), corresponding to the c$_{E}$ term. The last two columns show B ( $^{4}$He) and $^{2}$a$_{nd}$ . For the sake of comparison, in the first row, the original values of the parameters have been considered ( b = b 0 , d = d 0 and c$_{E}$ = 0) with the value of the cutoff fixed to reproduce the triton binding energy (Λ = 4 . 8 m$_{π}$ ). As we can observe, in this case B ( $^{4}$He) is overestimated and $^{2}$a$_{nd}$ is underestimated. When the E -term is considered, the description of B ( $^{4}$He) improves and it seems that a low value of Λ is preferable. A further analysis of these parametrizations is given Sec. IV studying some 10