I am an international student who would be applying for graduate admissions this fall. After seeing the results of applicants over the past few years, I am feeling intimidated with applying to theory. I have decent research experience in quantum computation and quantum information and have very recently started working on QFT and Strings at my institute. I'll also be taking some graduate level courses next sem in QFT and advanced mathematical physics. I am not 100% sure of my exact research interest but I mostly want to work on the integration of QI in HEP theories. That being said, would I increase my chances of being accepted in top schools for theory if I applied for QI rather than my exact interest (That is applying purely for QI and not mentioning any HEP, QFT, Strings etc.) ? As HEP-th seems to be extremely competitive. And how much flexibility do students have when it comes to graduate research? Are there any cases where students select their advisers later in the course instead of on entry?