Abstract

The local Callan-Symanzik equation describes the response of a quantum field theory to local scale transformations in the presence of background sources. The consistency conditions associated with this anomalous equation imply non-trivial relations among the $\beta$-function, the anomalous dimensions of composite operators and the short distance singularities of correlators. In this paper we discuss various aspects of the local Callan-Symanzik equation and present new results regarding the structure of its anomaly. We then use the equation to systematically write the n-point correlators involving the trace of the energy-momentum tensor. We use the latter result to give a fully detailed proof that the UV and IR asymptotics in a neighbourhood of a 4D CFT must also correspond to CFTs. We also clarify the relation between the matrix entering the gradient flow formula for the $\beta$-function and a manifestly positive metric in coupling space associated with matrix elements of the trace of the energy momentum tensor.

Highlights

  • The source method is a well established tool for probing the structure of Quantum Field Theory (QFT)

  • The basic idea, as sketched in figure 1, is to turn on all the possible marginal deformations of the conformal field theory (CFT), which we describe by a set of independent couplings λI, I = 1, . . . , N, such that λI = 0 corresponds to the unperturbed CFT

  • Like for gauge symmetry, unambiguous physical information is carried by the invariants, which in our case these are given by begin only at order (BI) = βI − SATAλ I

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Summary

Introduction

The source method is a well established tool for probing the structure of Quantum Field Theory (QFT). The original goal of this paper was to illustrate all these details and to present a systematic method for computing correlation functions of T off-criticality We achieved this goal by studying and applying the local Callan-Symanzik equation. We show that most of these conditions can be explicitly solved and that the anomaly can be reformulated in a manifestly consistent form, with only 3 non-trivial consistency conditions remaining One combination of these is the famous equation (1.2), while two others, involve anomalies related to external gauge fields.

General set-up
The structure of Weyl symmetry
The local CS equation and the operator algebra
Ward identities and ambiguities
Lie derivatives
Consistency conditions
Dimension 2 covariant functions
Limiting cases
Comments on the R2 anomaly
Weyl consistency conditions and gradient flows
Gradient flow for the vector β-functions?
The dilaton effective action
Computation of Γlocal
Correlators of T and the constraints on the RG flow
Conclusions
B Weyl symmetry in a regulated theory
The variation of AAμ
Dim 2 operators
Consistency conditions for the anomaly coefficients
C Unitarity and anomalous dimensions of currents
D The consistency conditions for the Weyl anomaly

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