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Measurement of photonuclear jet production in ultraperipheral Pb+Pb collisions at √NN =5.02  TeV

Aad, G. ; Åkesson, T.P.A. LU orcid ; Astrand, K.S.V. LU ; Doglioni, C. LU ; Ekman, P.A. LU orcid ; Hedberg, V. LU ; Herde, H. LU orcid ; Konya, B. LU ; Lytken, E. LU orcid and Poettgen, R. LU orcid , et al. (2025) In Physical Review D 111(5).
Abstract
In ultrarelativistic heavy ion collisions at the LHC, each nucleus acts a sources of high-energy real photons that can scatter off the opposing nucleus in ultraperipheral photonuclear ((Formula presented)) collisions. Hard scattering processes initiated by the photons in such collisions provide a novel method for probing nuclear parton distributions in a kinematic region not easily accessible to other measurements. ATLAS has measured production of dijet and multijet final states in ultraperipheral (Formula presented) collisions at (Formula presented) using a dataset recorded in 2018 with an integrated luminosity of (Formula presented). Photonuclear final states are selected by requiring a rapidity gap in the photon direction; this selects... (More)
In ultrarelativistic heavy ion collisions at the LHC, each nucleus acts a sources of high-energy real photons that can scatter off the opposing nucleus in ultraperipheral photonuclear ((Formula presented)) collisions. Hard scattering processes initiated by the photons in such collisions provide a novel method for probing nuclear parton distributions in a kinematic region not easily accessible to other measurements. ATLAS has measured production of dijet and multijet final states in ultraperipheral (Formula presented) collisions at (Formula presented) using a dataset recorded in 2018 with an integrated luminosity of (Formula presented). Photonuclear final states are selected by requiring a rapidity gap in the photon direction; this selects events where one of the outgoing nuclei remains intact. Jets are reconstructed using the anti-(Formula presented) algorithm with radius parameter, (Formula presented). Triple-differential cross sections, unfolded for detector response, are measured and presented using two sets of kinematic variables. The first set consists of the total transverse momentum ((Formula presented)), rapidity, and mass of the jet system. The second set uses (Formula presented) and particle-level nuclear and photon parton momentum fractions, (Formula presented) and (Formula presented), respectively. The results are compared with leading-order perturbative QCD calculations of photonuclear jet production cross sections, where all leading order predictions using existing fits fall below the data in the shadowing region. More detailed theoretical comparisons will allow these results to strongly constrain nuclear parton distributions, and these data provide results from the LHC directly comparable to early physics results at the planned Electron-Ion Collider. © 2025 CERN, for the ATLAS Collaboration. (Less)
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author collaboration
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Physical Review D
volume
111
issue
5
article number
052006
publisher
American Physical Society
external identifiers
  • scopus:105001200288
ISSN
2470-0010
DOI
10.1103/PhysRevD.111.052006
language
English
LU publication?
yes
id
595a4ff8-70ac-4bd2-a556-c7cf79a9d41e
date added to LUP
2026-03-05 14:31:10
date last changed
2026-03-05 14:50:20
@article{595a4ff8-70ac-4bd2-a556-c7cf79a9d41e,
  abstract     = {{In ultrarelativistic heavy ion collisions at the LHC, each nucleus acts a sources of high-energy real photons that can scatter off the opposing nucleus in ultraperipheral photonuclear ((Formula presented)) collisions. Hard scattering processes initiated by the photons in such collisions provide a novel method for probing nuclear parton distributions in a kinematic region not easily accessible to other measurements. ATLAS has measured production of dijet and multijet final states in ultraperipheral (Formula presented) collisions at (Formula presented) using a dataset recorded in 2018 with an integrated luminosity of (Formula presented). Photonuclear final states are selected by requiring a rapidity gap in the photon direction; this selects events where one of the outgoing nuclei remains intact. Jets are reconstructed using the anti-(Formula presented) algorithm with radius parameter, (Formula presented). Triple-differential cross sections, unfolded for detector response, are measured and presented using two sets of kinematic variables. The first set consists of the total transverse momentum ((Formula presented)), rapidity, and mass of the jet system. The second set uses (Formula presented) and particle-level nuclear and photon parton momentum fractions, (Formula presented) and (Formula presented), respectively. The results are compared with leading-order perturbative QCD calculations of photonuclear jet production cross sections, where all leading order predictions using existing fits fall below the data in the shadowing region. More detailed theoretical comparisons will allow these results to strongly constrain nuclear parton distributions, and these data provide results from the LHC directly comparable to early physics results at the planned Electron-Ion Collider. © 2025 CERN, for the ATLAS Collaboration.}},
  author       = {{Aad, G. and Åkesson, T.P.A. and Astrand, K.S.V. and Doglioni, C. and Ekman, P.A. and Hedberg, V. and Herde, H. and Konya, B. and Lytken, E. and Poettgen, R. and Smirnova, O. and Wallin, E.J. and Zwalinski, L.}},
  issn         = {{2470-0010}},
  language     = {{eng}},
  number       = {{5}},
  publisher    = {{American Physical Society}},
  series       = {{Physical Review D}},
  title        = {{Measurement of photonuclear jet production in ultraperipheral Pb+Pb collisions at √NN =5.02  TeV}},
  url          = {{http://dx.doi.org/10.1103/PhysRevD.111.052006}},
  doi          = {{10.1103/PhysRevD.111.052006}},
  volume       = {{111}},
  year         = {{2025}},
}