I'm looking for a book that describes Quantum Field Theory from a group theory approach for mathematical physicists (with emphasis on the physic part). Ideally I want it to first describe and define groups, representations and irreducible representations. The more rigorous the math, the better (but it shouldn't drown in technicalities of course). If you have ever read Robert Wald's book on General Relativity, it should ideally have the same kind of structure (I love that book!). Anybody know a book like this?