Unveiling the dynamics of long-range correlations in high-multiplicity jets through substructure engineering in pp collisions at CMS

Rice University, 6100 Main St, Houston, TX 77005, USA

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Published online: 17 April 2026

Abstract

Recent CMS data have revealed long-range correlations at high charged-particle multiplicity (N_ch^j) within jets produced in proton-proton (pp) collisions, suggesting collective behavior in systems much smaller than those typical of heavy ion collisions. In the polar coordinate system about the reconstructed jet axis, two-particle azimuthal correlations show an unexpected rise in elliptic anisotropy (v₂^*) at large pseudorapidity separations (Δη^* > 2) as a function of N_ch^j, a trend not reproduced by event generators like pythia or sherpa. In this paper, we present detailed measurements of long-range correlations using LHC Run 2 data for pp collisions at √s = 13 TeV and compare the results with model predictions. The transverse momentum and Δη^* dependence of v₂^* is shown across a wide range in N_ch^j. Furthermore, the role of jet substructure, particularly in jets exhibiting two-prong features, is examined to unveil a potential connection between the v₂^* enhancement and the initial-state jet geometry. A surprising increase in v₂^* emerges exclusively in these two-prong jets at high N_ch^j.