I was reading a little bit about N = 4 SUSY, and I couldn't help but think that it's like the Pati Salam GUT. To get an N = 4 SUSY theory you can take SO(1,9) and compactify it to four dimensions. In doing so, you get Spin(1,3)XSU(4), where SU(4) is the R symmetry of the theory and Spin(1,3)...