Model for Thermal Relic Dark Matter of Strongly Interacting Massive Particles
Phys. Rev. Lett. 115 (2015) 021301
Provides the first calculable realization of the SIMP mechanism using a QCD-like hidden sector where pseudo-Nambu-Goldstone bosons are the dark matter and the Wess-Zumino-Witten term mediates the 3-to-2 number-changing process.