From looking at the online department pages, there certainly *are* international HEP-Th graduate students at schools like Princeton, Harvard, Stanford, Caltech and MIT but they are clearly an extreme minority compared to the vast number of international applicants who are rejected.
So what is it that these students do that signals them out from the rest? Do you essentially have to have perfect academics (i.e. 4.0 GPA, 990 PGRE, top of your year, advanced graduate classes)? Do you need to attend a top international university like Cambridge, Oxford or Moscow State? Or is it mainly down to whether or not you can get research papers published as an undergraduate in respected journals?
Can someone please paint a picture of what a success HEP-Th international applicant at a top 5 US school would look like?