Hi, I have forgotten all about my supersymmetry knowledge and all about my group theory knowledge. I am trying to understand what the R-symmetry in N=4 U(N) SYM does. Sadly I have never actually learnt anything about supersymmetry which is larger than N=1. I know the R-symmetry is SU(4) and I know that the gauge boson doesn't transform under R-symmetry. The 6 real scalars are "a 6" or SU(4) and the four Weyl fermions "a 4". So the question is: What does "a 6" and "a 4" mean? I know that means they are in different representations of SU(4). Does that mean the scalars transform into each other and the fermions transform into each other seperately and leave the particles in the other rep alone? If so, I thought R-symmetry came from supersymmetry, which basically transforms fermions into bosons and vice versa. Please, could you try and answer in not too technical term? Thanks so much!