The study of nuclear systems composed exclusively of neutrons is a signi can’t significant topic in nuclear physics. Interest has increased after the publication of experimental results and theoretical calculations using realistic nucleon-nucleon (NN) interaction models, which claim the existence of a four-neutron resonant state.

In the present work, an approach for obtaining the energies and widths of possible resonances in a three neutron system is proposed, based on calculations within the no-core shell model with realistic NN forces. The three-body continuum is taken into account within the democratic decay approximation.