Amplitudes in CFT vanish. Why does N=4 have them?

earth2

Hi guys,

one question in this growing amplitude business that i don't understand. Usually one says that conformal field theories do not have any non-trivial scattering amplitudes because one cannot define asymptotic states. But say we consider now N=4 Super Yang Mills and moreover treelevel. It is a conformal theory but it has non-vanishing amplitudes, like the infamous MHV amplitude. How can that be that an conformal field theory has non-vanishing amplitudes?

Cheers,
earth2

sheaf

I think they have a method of breaking the conformal invariance in a controlled way. If you google "Bern Dixon Smirnov" or "BDS" you might turn up some information on the computation of IR safe amplitudes in these theories. I don't really understand it well enough to explain it though...