Color Grosse-Wulkenhaar models: One-loop $\beta$-functions
  The $\beta$-functions of O(N) and U(N) invariant Grosse-Wulkenhaar models are computed at one loop using the matrix basis. In particular, for ``parallel interactions", the model is proved asymptotically free in the UV limit for $N >1$, and has a triviality problem or Landau ghost for $N<1$. The vanishing $\beta$-function is recovered solely at N=1. We discuss various possible consequences of these results. 
Joseph Ben Geloun and Vincent Rivasseau