Probing magnetic line defects with two-point functions

This paper studies magnetic line defects in the Wilson-Fisher $O(N)$ model. A powerful method to probe the system is to consider mixed two-point functions of the order parameter and the energy operator in the presence of the defect. A recently developed dispersion relation allows us to bootstrap these mixed correlators to leading order in the $\epsilon$-expansion. We also carry out explicit diagrammatic calculations, finding perfect agreement with the bootstrap, and we conclude extracting the new CFT data predicted by the two-point functions.