Energy correlations: from QCD to gravity

Energy correlations are infrared-safe observables that measure the flux of energy deposited in calorimeters located at different points on the celestial sphere, thereby encoding detailed information about the dynamics of the underlying theory. Originally introduced to characterize hadronic final states in $e^+e^-$ annihilation, they play a central role in the study of jet substructure and precision QCD collider phenomenology. I will review the modern reformulation of energy correlations as correlation functions of asymptotic detector operators---defined as light-ray operators acting at null infinity---and show how this framework naturally extends to perturbative quantum gravity in asymptotically flat spacetimes. In the gravitational setting, the corresponding detector operators probe the angular distribution of outgoing graviton radiation and define gravitational analogues of the energy correlations familiar from QCD. Using these tools, I will present the computation of energy correlators in perturbative quantum gravity at leading nontrivial order in the gravitational coupling.