Prediction for a Four-Neutron Resonance

We utilize various ab initio approaches to search for a low-lying resonance in the four-neutron (4n) system using the JISP16 realistic NN interaction. Our most accurate prediction is obtained using a J-matrix extension of the no-core shell model and suggests a 4n resonant state at an energy near E_{r}=0.8 MeV with a width of approximately Γ=1.4 MeV.