I've heard that there is a belief that interacting conformal field theories do not exist in dimensions greater than 6, and in 6D the only known nontrivial CFTs are superconformal field theories. What is the argument that these theories can't exist in higher dimensions? I have a sense that 10D is rather special, and I wonder if there could exist a superconformal field theory in 10 spacetime dimensions.
An explanation of the general argument for/against higher dimensional (super)conformal field theories, and/or links to references discussing this would be very helpful.