$\mathcal{N}=2$ Universality at Strong Coupling

Abstract

We present a detailed analysis of integrated correlators for an $\mathcal{N}=2$ superconformal field theory on a squashed sphere with SU$(N)$ gauge group and fundamental/anti-symmetric matter. Employing the matrix model arising from supersymmetric localisation, we compute derivatives of the partition function $\mathcal{Z}$ with respect to the fundamental mass ($\hat{I}¼$), the anti-symmetric mass ($m$) and the squashing parameter ($b$), corresponding to integrated insertions of the $\mathcal{N}=2$ flavour-current and stress-tensor multiplets, which are holographically dual to gluon and graviton scatterings in the presence of D7-branes. For correlators dual to only graviton scatterings, we confirm the planar-limit equivalence with $\mathcal{N}=4$ SYM. Our main result is a remarkable universality for the mixed gluon-graviton scattering amplitudes off D7-branes, obtained from ${\partial }_{\hat{I}}{¼}^2{\partial }_m^2\log \mathcal{Z}$ and ${\partial }_{\hat{I}}{¼}^2{\partial }_b^2\log \mathcal{Z}$. We show that the leading and sub-leading large-$N$ contributions in the strong-coupling regime are governed by universal asymptotic series, identical to those found for integrated giant-graviton correlators in $\mathcal{N}=4$ SYM. We also propose an $\text{SL}(2,\mathbb{Z})$-invariant completion of these results in terms of non-holomorphic Eisenstein series. This completion provides exact constraints on higher-derivative terms in the dual ${\text{AdS}}_5$ brane-string amplitudes and highlights an unexpected universality across distinct superconformal theories at strong coupling.

63 pages, several appendices, Mathematica ancillary file attached; v2: typos fixed, matches published version