  A new effective field theory has been developed to describe shallow $P$-wave
resonances using nonlocal, momentum-dependent two-body potentials. This
approach is expected to facilitate many-body calculations and has been
demonstrated to converge and to be renormalizable in perturbative calculations
at subleading orders. The theory has been applied to the neutron-alpha system,
with good agreement found between its predictions and a phase-shift analysis of
neutron-alpha elastic scattering. In the three-body system consisting of two
neutrons and an alpha particle, the nonlocal potential in this framework has
been found to recover the same qualitative features as previously shown with
energy-dependent formulations.
