2024/09/19 by ALICE Collaboration
#FOS: Physical sciences #High Energy Physics - Experiment (hep-ex) #Nuclear Experiment (nucl-ex)
paper · doi:10.48550/arxiv.2409.12687
This paper presents a fully-corrected measurement of the energy-energy correlator (EEC) within jets in pp collisions. The EEC traces the energy flow as a highly energetic parton undergoes a QCD shower followed by the confinement of partons into hadrons, probing the correlation function of the energy flow inside jets. The EEC observable is measured as a function of the charged particle pair angular distance, R\rm L, for 20 < p\rm T\rm ch jet < 80 GeV/c. In the perturbative region (large R\rm L), a good agreement between the data and a next-to-leading-log perturbative QCD calculation is observed. In the non-perturbative region (small R\rm L), the data exhibits a linear R\rm L dependence. There is a transition region in between, characterized by a turnover in the EEC distribution, corresponding to the confinement process. The peak of this transition region is located at 2.39 ± 0.17 GeV/c/⟨ p\rm T\rm ch jet⟩ for jets of various energies, indicating a common energy scale for the hadronization process. State-of-the-art Monte Carlo event generators are compared with the measurements, and can be used to constrain the parton shower and hadronization mechanisms.