A limit for large $R$-charge correlators in $mathcal{N}=2$ theories

Using supersymmetric localization, we study the sector of chiral primary operators $({rm Tr} , phi^2 )^n$ with large $R$-charge $4n$ in $mathcal{N}=2$ four-dimensional superconformal theories in the weak coupling regime $grightarrow 0$, where $lambdaequiv g^2n$ is kept fixed as $ntoinfty $, $g$ representing the gauge theory coupling(s). In this limit, correlation functions $G_{2n}$ of these operators behave in a simple way, with an asymptotic behavior of the form $G_{2n}approx F_{infty}(lambda) left(frac{lambda}{2pi e}right)^{2n} n^alpha $, modulo $O(1/n)$ corrections, with $alpha=frac{1}{2} mathrm{dim}(mathfrak{g})$ for a gauge algebra $mathfrak{g}$ and a universal function $F_{infty}(lambda)$. As a by-product we find several new formulas both for the partition function as well as for perturbative correlators in ${cal N}=2$ $mathfrak{su}(N)$ gauge theory with $2N$ fundamental hypermultiplets.