Stealth QCD-like Strong Interactions and the t-tbar Asymmetry
  We show that a new strongly interacting sector can produce large enhancements of the t-tbar asymmetries at the Tevatron. The Standard Model is extended by a new vector-like flavor triplet of fermions and one heavy scalar, all charged under a hypercolor gauge group SU(3) HC. This simple extension results in a number of new resonances. The predictions of our model are rather rigid once a small number of UV parameters are fixed, since all the strong dynamics can be directly taken over from our understanding of QCD dynamics. Despite the rather low hypercolor confinement scale of ~100 GeV, the new strongly interacting sector is stealth. It is shielded from present direct and indirect NP searches since the light resonances are QCD singlets, whereas the production of the heavier QCD colored resonances leads predominantly to high multiplicity final states. Improved searches can potentially be devised using top tagged final states or decays into a small number of hypercolor pions. 
Joachim Brod, Jure Drobnak, Alexander L. Kagan, Emmanuel Stamou, Jure   Zupan
hep-ph hep-ex