  We study the single-particle spectral function of resonantly-interacting
fermions in the unitary regime, as described by the three-dimensional
attractive Hubbard model in the dilute limit. Our approach, based on the
Dynamical Cluster Approximation and the Maximum Entropy Method, shows the
emergence of a gap with decreasing temperature, as reported in recent cold-atom
photoemission experiments, for coupling values that span the BEC-BCS crossover.
By comparing the behavior of the spectral function to that of the imaginary
time dynamical pairing susceptibility, we attribute the development of the gap
to the formation of local bound atom pairs.
