Description
The O(N) Non-Linear Sigma Model (NLSM) in d=2+epsilon has long been conjectured to describe the same conformal field theory as the Wilson-Fisher O(N) fixed point obtained from the (phi^2)^2 model in
d=4-epsilon. In this talk, we put this conjecture into question, building on the recent observation [Jones,2024] that the NLSM CFT possesses a protected operator with dimension N-1, which is instead absent in the WF O(N) CFT. We propose several scenarios that may explain this discrepancy.