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

Recent CMS data have revealed long-range correlations at high charged-particle multiplicity (Nchj) 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 Nchj, a trend not reproduced by event generators like <ns0:sc>pythia </ns0:sc>or <ns0:sc>sherpa</ns0:sc>. 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 Nchj. 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 Nchj.