For more than half-century, our understanding of quantum degenerate gases has been very much  based on the dilute-gas theories which are applicable in the limit of weak scattering. Ultra-cold gases near resonance are a new platform that experimentalists have been using to explore exciting physics beyond the dilute limit. This unique opportunity also poses a great challenge to theorists in the community:  how to further regularize the formally divergent energy density appearing in the dilute gas theory.

In this talk, I am going to report recent progress made on resumation of most divergent contributions to the energy density of Bose gases near resonance. Our result suggests that Bose gases near resonance should be nearly fermionized. I will also discuss the relation to the Lee-Yang-Huang corrections, estimation of the three-body correlations.