Light-rays and detectors in Wilson-Fisher theory

In conformal field theory, in contrast to gapped theories, S-matrix is not well-defined. Similarly, various inclusive observables which make sense in a gapped theory, such as "energy squared" calorimeters, suffer from IR divergences in CFTs. Using the example of Wilson-Fisher theory, I will discuss how these observables can be renormalized and what is the physical meaning of their anomalous dimensions. Identifying these observables with light-ray operators, I will discuss various related features of the Chew–Frautschi plot in Wilson-Fisher theory, and in particular identify the leading order pomeron operator in this model.