Recently I heard some seminar on higher spin gauge theory, and got some interest. I know there are some no-go theorems in quantum field theories:
Weinberg: Massless higher spin amplitudes are forbidden by the general form of the S-mastrix.
Coleman-Mandula: There is no conserved higher spin charge/current, considering nontrivial S-matrix and mass gap formalism.
The speaker says, that by introducing a cosmological constant, i.e. introducing AdS space, one can avoid these no go theorems, but I am not sure how.
Can you give me some explanation for this?
My reference is a talk by Xi Yin, page 5.