Vyacheslav "Slava" Rychkov (Вячеслав Рычков)
Permanent professor of theoretical physics, Institut des Hautes Études Scientifiques
What's new:
29/07/2025
I am attending the Bootstrap 2025 program at the Instituto Principia in São Paulo, Brazil, where Fabiana De Cesare spoke today about our recent work "Disturbing news about the \(2+\epsilon\) expansion". I invite you to watch her excellent talk. The \(2+\epsilon\) expansion of the \(O(N)\) nonlinear sigma model is a classic subject going back to the work of Polyakov, Brézin, and Zinn-Justin in the 1970's. Most people believe that if properly done it should give the same critical exponents in \(d=3\) as the \(4-\epsilon\) expansion of Wilson and Fisher. However as our work explains, this is unlikely to be true, at least if one uses the standard textbook implementation. This expansion may instead describe some other family of theories. An interesting open problem is how to modify the \(2+\epsilon\) expansion so that this problem is resolved. Future work will hopefully clarify the situation.
10/07/2025
Time to stop relying on Google. I moved from gmail to protonmail. I also moved my personal website from google sites to the ihes domain over here, editable through a CNRS hosting platform.