학술논문

Azimuthal correlations in photoproduction and deep inelastic ep scattering at HERA
Document Type
article
Source
Journal of High Energy Physics, Vol 2021, Iss 12, Pp 1-22 (2021)
Subject
Collective flow
Lepton-Nucleon Scattering (experiments)
Particle correlations and fluctuations
Quark gluon plasma
Nuclear and particle physics. Atomic energy. Radioactivity
QC770-798
Language
English
ISSN
1029-8479
Abstract
Abstract Collective behaviour of final-state hadrons, and multiparton interactions are studied in high-multiplicity ep scattering at a centre-of-mass energy s $$ \sqrt{s} $$ = 318 GeV with the ZEUS detector at HERA. Two- and four-particle azimuthal correlations, as well as multiplicity, transverse momentum, and pseudorapidity distributions for charged-particle multiplicities N ch ≥ 20 are measured. The dependence of two-particle correlations on the virtuality of the exchanged photon shows a clear transition from photoproduction to neutral current deep inelastic scattering. For the multiplicities studied, neither the measurements in photoproduction processes nor those in neutral current deep inelastic scattering indicate significant collective behaviour of the kind observed in high-multiplicity hadronic collisions at RHIC and the LHC. Comparisons of PYTHIA predictions with the measurements in photoproduction strongly indicate the presence of multiparton interactions from hadronic fluctuations of the exchanged photon.