Generalized spectral form factors and the statistics of heavy operators

Abstract

The spectral form factor is a powerful probe of quantum chaos that diagnoses the statistics of energy levels, but is blind to other features of a theory such as matrix elements of operators or OPE coefficients in conformal field theories. In this paper, we introduce generalized spectral form factors: new probes of quantum chaos sensitive to the dynamical data of a theory. These quantities can be studied using random matrix theory and an effective theory of quantum chaos. We focus our attention on a particular combination of heavy-heavy-heavy OPE coefficients that generalizes the genus-2 partition function of two-dimensional CFTs, for which we define a form factor. Assuming that random matrix theory applies to chaotic CFTs, we probe heavy-heavy-heavy OPE coefficients and find statistical correlations that agree with the OPE Randomness Hypothesis: these coefficients have a random tensor component. The EFT of quantum chaos predicts that the genus-2 form factor displays a ramp and a plateau. Our results suggest that this is a common property of generalized spectral form factors.