Search for the Production of Quark-Gluon Plasma in $e^+ e^-$ Collisions at $\sqrt{s}$ = 91.2 GeV with Archived ALEPH LEP1 Data

Measurements of two-particle angular correlations for charged particles emitted in $e^+ e^-$ collisions at a center-of-mass energy of 91 GeV are presented. The archived data are collected with the ALEPH detector at LEP. The correlation functions are measured over a broad range of pseudorapidity and full azimuth as a function of charged particle multiplicity. No significant long-range correlation is observed in both the lab coordinate analysis and in the thrust coordinate analysis, where the later is sensitive to a medium expanding around the color string between the out-going $q \bar{q}$ pair from the 𝑍 boson decay. The associated yield distributions in both analyses are in better agreement with predictions from the pythia event generator than those from herwig, providing new insights into the hadronization modeling. These results serve as an important reference to the observed long-range correlation in proton-proton, proton-nucleus and nucleus-nucleus collisions.