Renormalised CFT 3-point functions of scalars, currents and stress tensors

TL;DR

This paper analyzes the renormalization of mixed 3-point functions involving scalars, currents, and stress tensors in conformal field theories, revealing new anomalies, beta functions, and universal tensor structures in various dimensions.

Contribution

It provides a comprehensive non-perturbative momentum-space analysis of all renormalized 3-point functions involving scalars, currents, and stress tensors, identifying anomalies and beta functions across dimensions.

Findings

Identification of all anomalies and beta functions in 3-point functions.

Explicit results for dimensions d=3,4 for stress tensors, currents, and scalars.

Discovery of universal tensor structures independent of scalar dimensions.

Abstract

We discuss the renormalisation of mixed 3-point functions involving tensorial and scalar operators in conformal field theories of general dimension. In previous work we analysed correlators of either purely scalar or purely tensorial operators, in each case finding new features and new complications: for scalar correlators, renormalisation leads to beta functions, novel conformal anomalies of type B, and unexpected analytic structure in momentum space; for correlators of stress tensors and/or conserved currents, beta functions vanish but anomalies of both type B and type A (associated with a $0/0$ structure) are present. Mixed correlators combine all these features: beta functions and anomalies of type B, plus the possibility of new type A anomalies. Following a non-perturbative and general momentum-space analysis, we present explicit results in dimensions $d=3,4$ for all renormalised 3-point functions of stress tensors, conserved currents and scalars of dimensions $\Delta=d$ and $\Delta=d-2$. We identify all anomalies and beta functions, and explain the form of the anomalous conformal Ward identities. In $d=3$, we find a $0/0$ structure but the corresponding type A anomaly turns out to be trivial. In addition, the correlators of two currents and a scalar, and of two stress tensors and a scalar, both feature universal tensor structures that are independent of the scalar dimension and vanish for opposite helicities.