I'm a newcomer to Quatum Field Theory, recently I started to work with the very basic book of . My final destination is to learn Conformal Field Theory applied to Quantum Phase Transitions and Condesed matter.  What would be a second book in QFT towards this aim? I ask this because many of them are oriented towards high energy and particles, which I'm not sure I will need all of those topics.  Finally, I would like to say that I have  book, but it's not well suitable for self-studying since it has a lot of typos.
I have a background in QFT, GR and differential geometry at the level of a master student in theoretical physics. I would like to touch the area of CFT. I know the textbook of Philippe Di Francesco. It may be too big for the beginner like me. Are there some good introductory lectures or textbooks adapted to the needs of beginners?
In .NET, what's the best way to prevent multiple instances of an app from running at the same time? And if there's no "best" technique, what are some of the caveats to consider with each solution?