A formalism for constructing the QCD power spectrum with finite sampling

Abstract

Recent progress in the study of QCD phenomena with energy correlators motivates novel approaches to explore the information contained in the QCD radiation spectrum. Fox-Wolfram moments are a set of observables that characterize the angular distribution of energy flow in high-energy collisions. Contrary to their conventional application, they are a class of correlated moments that cannot be reduced to one or several characteristic ones. We present a formalism to extract their fully correlated information content, while systematically discarding small-angle sampling noise, on an event-by-event basis. We show that our approach circumvents a common misspecification of the data in terms of $\delta$-distributions, and is essential in keeping the power spectrum infrared and collinear safe. Our formalism introduces a means of accounting for the varying spatial extent of objects that enter the calculation of the power spectrum, with which experimental artifacts such as detector element geometries and measurement uncertainties can readily be incorporated.