Speaker
Description
Recent CMS data revealed intriguing long-range correlations within high-multiplicity jets produced in proton-proton collisions, suggesting the potential onset of collective behavior, typically associated with heavy-ion collisions, at much smaller scales. Two-particle correlations in the “jet frame” show a surprising rise in elliptic flow harmonics, v2, at large pseudorapidity separations (Δη > 2), in jets with high charged-particle multiplicities, a trend not reproduced by event generators like Pythia and Sherpa. In this talk, we present the transverse momentum and ∆η* dependence of elliptic and triangular flow, across a wide range of jet multiplicity and transverse momentum. We further explore the role of jet substructure in driving the observed long-range azimuthal correlations, examining its potential connection to the geometry of the initial-state jet system. Recent LHC studies also show signs of collectivity in high-multiplicity photonuclear collisions, where a quasi-real photon from one nucleus interacts with the other nucleus. In this talk, we also present new CMS measurements of two- and multi-particle correlations from photonuclear collisions using PbPb data at $\sqrt{s_{NN}} = 5.36$ TeV collected during the LHC Run 3. By leveraging the full detector acceptance, we explore wide pseudorapidity gaps up to 7–8 units, which significantly reduces non-collective contributions and enhances the search for long-range near-side ridge effects. Elliptic and triangular azimuthal anisotropies are extracted as functions of particle transverse momentum and event multiplicity.
| Category | Experiment |
|---|---|
| Collaboration (if applicable) | CMS |
