C# Generics Research Papers
Most of the important work on generics for C# was done by Andrew Kennedy at Microsoft Research Cambridge. He has a web page devoted to the topic. A fairly recent paper discussion the foundations is this one (which definitely looks like theory to me).

More recent, but interesting, work went into the design of C$\omega$. Also looking at the rather large amount of literature on Java generics, such as Featherweight Java, will also help. If you really want to start looking at the foundations, consider Cardelli's work on Types and Semantics, and perhaps consider looking at System F (and the original papers of Reynolds and Girard).