Speaker
Description
We present a measurement of thrust, energy-energy correlators, and two-particle angular correlations of charged particles in $e^+e^-$ ) collisions at center-of-mass energies up to $\sqrt{s} = 209\,\mathrm{GeV}$, using newly released open data access from the DELPHI experiment at LEP-I and -II. The thrust and energy-energy correlator, measured with unprecedented resolution and precision, are compared with various MC and analytic predictions. These analyses, leveraging DELPHI’s unique detector geometry and reconstruction capabilities, complement previous DELPHI and recent ALEPH re-analysis results.
In addition, this study explores potential collective behavior in $e^+e^-$ collisions by analyzing angular correlations over a wide range of pseudo-rapidities and full azimuth, as a function of event charged-particle multiplicity with respect to thrust. Earlier LEP-I results at $ \sqrt{s} = 91\,\mathrm{GeV}$—primarily from $ Z $ boson decays, showed no significant long-range correlations and were consistent with PYTHIA v6.1 expectations. However, the higher-energy LEP-II environment introduces richer dynamics, including enhanced $ W^+W^- $ production and multi-jet final states, leading to higher multiplicities and more complex event topologies. Together with archived ALEPH and Belle data, they provide valuable benchmarks for future studies of collective behavior in high-energy collisions and broaden the landscape of correlation measurements in small collision systems.
