Seven- and eight-loop critical exponents of the three-dimensional Ising model
We determine the critical exponents $\eta$, $\nu$, and the correction-to-scaling exponent $\omega$ of the three-dimensional Ising universality class by resumming the recently computed seven- and eight-loop renormalization-group series in the $\epsilon=4-d$ expansion (O.~Schnetz, \textit{Phys. Rev. D} \textbf{97}, 085018 (2018); O.~Schnetz, \textit{Phys. Rev. D} \textbf{107}, 036002 (2023)). The resummation combines conformal mapping with a homographic transformation, while the resummation parameters are optimized according to two complementary criteria. This approach yields precise estimates of the critical exponents together with quantitative uncertainty estimates. We find that the error bar on $\eta$ decreases rapidly with increasing loop order, whereas this is the case neither for $\nu$ nor for $\omega$. Unexpectedly, although the estimated values are accurate in absolute terms, their slow convergence with the loop order leads to a slight but systematic tension with the conformal bootstrap estimates that are currently considered as the benchmark. We discuss several possible origins of this behavior and its implications for high-order resummations of perturbative renormalization-group series.