As the title says, I am interested in a textbook/reference that deals exclusively with the mathematical foundations of quantum mechanics, without (or, with minimal) physics involved.
As an example on what I am looking for, is a text in the flavor of (but more extensive than) the 2nd chapter of Nielsen & Chuang's "Quantum Computation and Quantum Information" which contains math formalism without any physics stuff involved.
Thanks
I am not sure how to do your "flavor" comparison for you, but you seem to be asking for "more but rigorous". In your shoes, I'd start from a modern bare minimum text such as
It is in today's language, covers the bases and the bare rigorous minimum you appear interested in, and eschews the alternate universe that absorbs mathematical physicists' and functional analysts' attention.