Three-nucleon force effects in A= 4 scattering: Study of the resonances of the α particle

We study the effect of the three-nucleon force (3NF) in p+3H and n+3He scattering at low energies. The used 3NF was derived from effective field theory at next-to-next-to-leading order. The four-nucleon scattering observables are calculated using the Kohn variational principle and the hyperspherical harmonics technique and the results are compared with available experimental data. We also extract information on the excited states of 4He from the calculated S-matrix