11th International Conference on Hard and Electromagnetic Probes of High-Energy Nuclear Collisions

Measurements of two-particle correlations in $pp$ collisions show the presence of long-range correlations along $\Delta\eta$ that are strikingly similar to those seen in heavy-ion collisions. The similarity between the $pp$ and heavy-ion measurements raises the possibility that a tiny droplet of the QGP is produced even in $pp$ collisions. However, models that attribute the correlation in $pp$ collisions to semi-hard processes, can qualitatively reproduce the measurements. Performing the $pp$ measurements while distinguishing between the particles from semi-hard processes, such as low-$p_{\mathrm{T}}$ jets, and the particles produced from soft interactions, can differentiate between these two origins of the $pp$ ridge. This talk presents measurements of two-particle correlations in $pp$ collisions at $\sqrt{s}=13$ TeV with two different particle-pair selections. In the first case, tracks associated with jets are excluded from the correlation analysis. This is shown to affect the magnitude of long-range correlations by only a few percent. New measurements of two-particle correlations, measured between tracks that are constituents of jets and tracks from the underlying event are also presented. These measurements can further elucidate the origin of the $pp$ ridge.