>>10824801(If you already had a course in particle physics, then)
I would suggest starting with "Quantum Field Theory: The Why, What and How", by Padmanabhan, and follow with "Quantum Field Theory for Mathematicians", by Ticciati. The 1st is an introduction that explains why QFT has to be the way it is. The 2nd is basically the same material as Peskin & Schroeder, but written in a more rigorous way, which mathematicians find clearer and easier. An alternative to these two books is "Quantum Field Theory and the Standard Model", by Schwartz. This one is comparatively easy for physicists and it's a comprehensive introduction to QFT. The problem is that it's not as rigorous as the other two. Physicists don't mind the lack of rigour that much, but it bothers mathematicians.
