CERN Accelerating science

ATLAS Slides
Report number	ATL-PHYS-SLIDE-2023-204
Title	Two-particle correlations in 13 TeV pp collisions and their sensitivity to jets / hard scatterings
Author(s)	Cole, Brian (Columbia University (US))
Corporate author(s)	The ATLAS collaboration
Collaboration	ATLAS Collaboration
Submitted to	11th International Conference on Hard and Electromagnetic Probes of High-Energy Nuclear Collisions (HP2023), Aschaffenburg, Germany, 26 - 31 Mar 2023
Submitted by	[email protected] on 31 May 2023
Subject category	Particle Physics - Experiment
Accelerator/Facility, Experiment	CERN LHC ; ATLAS
Free keywords	pp collisions ; Ridge ; jets ; HEAVYIONS
Abstract	Measurements of two-particle correlations in 𝑝𝑝 collisions show the presence of long-range correlations along Δ𝜂 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-𝑝T 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 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.