Hello! I want to do a PhD in Particle Physics and I was wondering what is the difference between UK (and Europe in general) and USA doctorate programs. I see that at Oxford for example you can do a DPhil in 4 years while in USA you need at least 6 and I was wondering why is that. Is it more in depth in USA? Where should I focus on applying? The field I want to pursue is theoretical particle physics. I studied at an American university, but I am from Europe. My main issue is that I don't want to spend 6 -7 years on phD, if I can finish it in 4, as Oxford is as good as Caltech or Stanford in most of the rankings, so I want to understand the differences between the programs better. Thank you!