Analysis note: measurement of energy-energy correlator in $e^{+}e^{-}$ collisions at $91$ GeV with archived ALEPH data

TL;DR

This paper presents a high-precision measurement of energy-energy correlators in archived ALEPH data from $e^+e^-$ collisions at 91 GeV, providing new insights into QCD energy flow and hadronization.

Contribution

It introduces a novel, highly differential analysis of archived LEP data using EECs, achieving unprecedented precision and angular resolution in testing QCD predictions.

Findings

Results agree with previous LEP measurements

Enhanced angular resolution at small angles and back-to-back regions

Deviations from Pythia simulations suggest areas for improved modeling

Abstract

Electron-positron ($e^+e^-$) collisions provide a clean environment for precision tests of Quantum Chromodynamics (QCD) due to the absence of hadronic initial-state effects. We present a novel analysis of archived ALEPH data from the Large Electron-Positron Collider at the $Z$ pole, leveraging energy-energy correlators (EECs) to study hadronic energy flow with unprecedented precision. The two-point EEC is measured as a function of the angular separation between particles spanning from the collinear to the back-to-back limits in a remarkably differential test of perturbative and non-perturbative QCD. The results are consistent with previous LEP measurements and provide significantly improved precision and finer angular binning resolution, especially at small angles and in the back-to-back limit. Comparisons with \textsc{pythia} 6 simulations show overall agreement, with deviations in key kinematic regions offering insights into hadronization. The measurement performed here connects to new opportunities for precision QCD studies in archived and future collider data.