Abstract

We consider the family of renormalizable scalar QFTs with self-interacting potentials of highest monomial ϕm below their upper critical dimensions {d}_c=frac{2m}{m-2} , and study them using a combination of CFT constraints, Schwinger-Dyson equation and the free theory behavior at the upper critical dimension. For even integers m ≥ 4 these theories coincide with the Landau-Ginzburg description of multi-critical phenomena and interpolate with the unitary minimal models in d = 2, while for odd m the theories are non-unitary and start at m = 3 with the Lee-Yang universality class. For all the even potentials and for the Lee-Yang universality class, we show how the assumption of conformal invariance is enough to compute the scaling dimensions of the local operators ϕk and of some families of structure constants in either the coupling’s or the ϵ-expansion. For all other odd potentials we express some scaling dimensions and structure constants in the coupling’s expansion.

Highlights

  • Relations among them [3]

  • The two key ideas behind this approach are to achieve consistency between conformal symmetry and the equations of motion through the use of the operatorial Schwinger-Dyson equations (SDE), and to ensure regularity with the Gaussian theory when the dimension approaches its upper critical value in a limiting procedure. Such a method has been able to reproduce the leading results for the -expansion of the Ising, Lee-Yang, and Tricritical Ising universality classes. These results are very amusing in that none of the standard methods of quantum field theory (QFT) are used, including perturbation theory and the renormalization group, but just the knowledge of free (Gaussian) theory results for the correlators given by the Wick contractions

  • In this subsection we look for the interacting fixed point value of the coupling g at leading order in

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Summary

Schwinger-Dyson consistency and CFT

The reason is that, since we are interested in the underlying conformal theory, which by definition does not depend on external scales, all couplings with positive mass dimension must vanish at criticality. Theories living in continuous dimensions have already been investigated as CFT with conformal bootstrap methods [19]: they are believed to violate unitarity through the appearance of complex conjugate pairs of scaling dimensions, which are probably related to “evanescent” operators that couple to the spectrum only at non-integer dimensionalities and are associated to states with negative norm [20].

Anomalous dimensions
Climbing up: γ2
Structure constants
Collecting the results: even potentials
Collecting the results: odd potentials
Conclusions
A Free theory
B Action of the Laplacian
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