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arXiv · 2312.05084

Long-range near-side correlation in $e^+e^-$ Collisions at 183-209 GeV with ALEPH Archived Data

Yu-Chen Chen·Yi Chen·Anthony Badea·Austin Baty·Gian Michele Innocenti·Marcello Maggi·Christopher McGinn·Michael Peters·Tzu-An Sheng·Jesse Thaler·Yen-Jie Lee
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Abstract

The first measurement of two-particle angular correlations for charged particles with LEP-II data is presented. The study is performed using archived hadronic $e^+e^-$ data collected by ALEPH at center-of-mass energies up to 209 GeV, above the $W^+W^-$ production threshold, which provide access to unprecedented charged-particle multiplicities and more complex color-string configurations if compared to previous measurements at LEP-I energies. An intriguing long-range near-side excess is observed in the correlation function measured with respect to the thrust axis in the highest multiplicity interval $N_{\mathrm{trk}}\geq 50$. Such a structure is not predicted by the Monte-Carlo simulation. The harmonic anisotropy coefficients $v_n$, which result from the Fourier expansion of the two-particle correlation functions, were also measured for the first time in $e^+e^-$ data, and compared to PYTHIA6 predictions and to the results obtained in proton-proton collisions. The results presented in the Letter provide novel experimental constraints on the formation of collective phenomena in point-like $e^+e^-$ collisions.

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Yu-Chen Chen, Yi Chen, Anthony Badea, Austin Baty, Gian Michele Innocenti, Marcello Maggi, Christopher McGinn, Michael Peters, Tzu-An Sheng, Jesse Thaler, Yen-Jie Lee. 2023-12-08. Long-range near-side correlation in $e^+e^-$ Collisions at 183-209 GeV with ALEPH Archived Data. https://doi.org/10.1016/j.physletb.2024.138957

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