Integral constraints for $\mathcal{N}=4$ super-Yang-Mills from a squashed sphere
Shai M. Chester, Ross Dempsey, Debaditya Pramanik, Silviu S. Pufu
TL;DR
The paper demonstrates that three new integral constraints on four-point correlators of the N=4 stress-tensor multiplet, derived from squashed S^4 deformations, are not independent but follow from the two previously known constraints via N=4 superconformal Ward identities. By combining supersymmetric localization inputs with Ward identities, the authors express all relevant integrated correlators in terms of the reduced correlator T(u,v) and standard conformal D- and overline{D}-functions, using a robust toolkit that includes 6d embeddings and SO(5) averaging. The main technical advance lies in constructing finite, crossing-invariant, and regulator-friendly Ward-identity expressions for both non-squashed and squashed deformations, and in demonstrating that the squashing-induced constraints are consequences of established Ward identities. The results have implications for conformal bootstrap studies of N=4 SCFTs and suggest a pathway to derive analogous independent constraints in other theories with less-than-maximal supersymmetry, potentially improving bootstrap bounds and cross-checks. Overall, the work strengthens the bridge between localization-derived data and the conformal bootstrap program by showing squashing yields no new independent integral constraints beyond the known ones in N=4 SYM.
Abstract
Supersymmetric localization and Ward identities have been used in the past several years to derive two integral constraints on the four-point function of the stress-tensor multiplet in $\mathcal{N} = 4$ super-Yang-Mills theory. These constraints are powerful tools for studying the theory, especially when used in tandem with analytic and/or numerical bootstrap techniques. In this paper, we consider three additional integral constraints that can be derived starting from the $\mathcal{N} = 4$ super-Yang-Mills theory placed on a squashed four-sphere. These constraints are technically much more challenging to derive than the ones in the literature, and much of the paper is devoted to developing techniques to make this computation tractable. Our end result is that these three constraints are implied by the two constraints already appearing in the literature.
