Energy Correlators of Spinning Sources

TL;DR

This paper introduces a new framework for analyzing energy correlators with spin, revealing their angular dependence, bounds, and potential to probe hard scattering processes in QCD.

Contribution

It develops a comprehensive framework for spinning energy correlators, including their angular structure, bounds, and calculations in QCD, expanding the toolkit for high-energy scattering analysis.

Findings

Spinning energy correlators are bounded by unitarity and energy positivity.

Extremal correlators are generated by pure spin states.

Spinning correlators are less sensitive to infrared effects, probing hard scattering.

Abstract

The $N$-point energy correlator measures the energy flux through $N$ detectors. We present a general framework that characterizes its full angular dependence in a series of \textit{spinning energy correlators}. These spinning correlators resurrect the angular momentum structure of both the source and the detector configuration, lost otherwise in inclusive measurements. We demonstrate that unitarity and energy positivity confine these correlators to a sharply bounded region, with the boundary realized by extremal correlators generated by pure spin states. We present a first calculation of spinning energy correlators in QCD as well as spinning energy-charge correlators. Their enhanced insensitivity to infrared dynamics opens up a new set of observables that directly probe the hard part of the scattering. Finally, we provide generalized sum rules, extended to spinning correlators and to conserved charges beyond energy.