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Oxana Smirnova

Oxana Smirnova

Senior Lecturer, Deputy Head of division

Oxana Smirnova

Measurement of the Sensitivity of Two-Particle Correlations in pp Collisions to the Presence of Hard Scatterings


  • G. Aad
  • T.P.A. Åkesson
  • Caterina Doglioni
  • Alexander Ekman
  • Vincent Hedberg
  • Hannah Herde
  • Balazs Konya
  • Else Lytken
  • Ruth Pöttgen
  • Nathan Daniel Simpson
  • Eleni Skorda
  • Oxana Smirnova

Summary, in English

A key open question in the study of multiparticle production in high-energy pp collisions is the relationship between the "ridge"-i.e., the observed azimuthal correlations between particles in the underlying event that extend over all rapidities-and hard or semihard scattering processes. In particular, it is not known whether jets or their soft fragments are correlated with particles in the underlying event. To address this question, two-particle correlations are measured in pp collisions at sqrt[s]=13 TeV using data collected by the ATLAS experiment at the LHC, with an integrated luminosity of 15.8 pb^{-1}, in two different configurations. In the first case, charged particles associated with jets are excluded from the correlation analysis, while in the second case, correlations are measured between particles within jets and charged particles from the underlying event. Second-order flow coefficients, v_{2}, are presented as a function of event multiplicity and transverse momentum. These measurements show that excluding particles associated with jets does not affect the measured correlations. Moreover, particles associated with jets do not exhibit any significant azimuthal correlations with the underlying event, ruling out hard processes contributing to the ridge.


  • Particle and nuclear physics
  • eSSENCE: The e-Science Collaboration
  • Department of Physics

Publishing year





Physical Review Letters





Document type

Journal article


American Physical Society


  • Subatomic Physics


  • article
  • case report
  • clinical article
  • correlation analysis
  • luminance




  • ISSN: 1079-7114