I am going to be applying to graduate programs for theory in the fall, and after discussing research with a few of my professors, my top research topic choice is Conformal Field Theories. Are CFT's a large enough area of study to be the focus of research for a graduate student? Also, will saying that I want to study CFT's in my applications be too specific/restrictive? Would it be better to just say that I want to study formal field theories? Thanks for any help.