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Underlying event properties in pp collisions at √s = 13 TeV

Acharya, S ; Adolfsson, Jonatan LU ; Christiansen, Peter LU ; Matonoha, Oliver LU ; Nassirpour, Adrian LU orcid ; Ohlson, Alice LU ; Oskarsson, Anders LU ; Richert, Tuva LU ; Vazquez Rueda, Omar LU and Silvermyr, David LU orcid , et al. (2020) In Journal of High Energy Physics 2020(4).
Abstract
This article reports measurements characterizing the Underlying Event (UE) associated with hard scatterings at midrapidity (|η| < 0.8) in pp collisions at s = 13 TeV. The hard scatterings are identified by the leading particle, the charged particle with the highest transverse momentum (pTleading) in the event. Charged-particle number-densities and summed transverse-momentum densities are measured in different azimuthal regions defined with respect to the leading particle direction: Toward, Transverse, and Away. The Toward and Away regions contain the fragmentation products of the hard scatterings in addition to the UE contribution, whereas particles in the Transverse region are expected to originate predominantly from the UE. The study... (More)
This article reports measurements characterizing the Underlying Event (UE) associated with hard scatterings at midrapidity (|η| < 0.8) in pp collisions at s = 13 TeV. The hard scatterings are identified by the leading particle, the charged particle with the highest transverse momentum (pTleading) in the event. Charged-particle number-densities and summed transverse-momentum densities are measured in different azimuthal regions defined with respect to the leading particle direction: Toward, Transverse, and Away. The Toward and Away regions contain the fragmentation products of the hard scatterings in addition to the UE contribution, whereas particles in the Transverse region are expected to originate predominantly from the UE. The study is performed as a function of pTleading with three different pT thresholds for the associated particles, pTtrack > 0.15, 0.5, and 1.0 GeV/c. The charged-particle density in the Transverse region rises steeply for low values of pTleading and reaches a plateau. The results confirm the trend that the charged-particle density in the Transverse region shows a stronger increase with s than the inclusive charged-particle density at midrapidity. The UE activity is increased by approximately 20% when going from 7 TeV to 13 TeV pp collisions. The plateau in the Transverse region (5 <pTleading< 40 GeV/c) is further characterized by the probability distribution of its charged-particle multiplicity normalized to its average value (relative transverse activity, RT) and the mean transverse momentum as a function of RT. Experimental results are compared to model calculations using PYTHIA 8 and EPOS LHC. The overall agreement between models and data is within 30%. These measurements provide new insights on the interplay between hard scatterings and the associated UE in pp collisions. [Figure not available: see fulltext.] © 2020, The Author(s). (Less)
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type
Contribution to journal
publication status
published
subject
keywords
Hadron-Hadron scattering (experiments)
in
Journal of High Energy Physics
volume
2020
issue
4
article number
192
publisher
Springer
external identifiers
  • scopus:85084153927
ISSN
1029-8479
DOI
10.1007/JHEP04(2020)192
language
English
LU publication?
yes
id
c6e5baaf-7167-4c03-881d-14807ec55464
date added to LUP
2021-01-12 09:15:01
date last changed
2023-04-11 03:40:11
@article{c6e5baaf-7167-4c03-881d-14807ec55464,
  abstract     = {{This article reports measurements characterizing the Underlying Event (UE) associated with hard scatterings at midrapidity (|η| &lt; 0.8) in pp collisions at s = 13 TeV. The hard scatterings are identified by the leading particle, the charged particle with the highest transverse momentum (pTleading) in the event. Charged-particle number-densities and summed transverse-momentum densities are measured in different azimuthal regions defined with respect to the leading particle direction: Toward, Transverse, and Away. The Toward and Away regions contain the fragmentation products of the hard scatterings in addition to the UE contribution, whereas particles in the Transverse region are expected to originate predominantly from the UE. The study is performed as a function of pTleading with three different pT thresholds for the associated particles, pTtrack &gt; 0.15, 0.5, and 1.0 GeV/c. The charged-particle density in the Transverse region rises steeply for low values of pTleading and reaches a plateau. The results confirm the trend that the charged-particle density in the Transverse region shows a stronger increase with s than the inclusive charged-particle density at midrapidity. The UE activity is increased by approximately 20% when going from 7 TeV to 13 TeV pp collisions. The plateau in the Transverse region (5 &lt;pTleading&lt; 40 GeV/c) is further characterized by the probability distribution of its charged-particle multiplicity normalized to its average value (relative transverse activity, RT) and the mean transverse momentum as a function of RT. Experimental results are compared to model calculations using PYTHIA 8 and EPOS LHC. The overall agreement between models and data is within 30%. These measurements provide new insights on the interplay between hard scatterings and the associated UE in pp collisions. [Figure not available: see fulltext.] © 2020, The Author(s).}},
  author       = {{Acharya, S and Adolfsson, Jonatan and Christiansen, Peter and Matonoha, Oliver and Nassirpour, Adrian and Ohlson, Alice and Oskarsson, Anders and Richert, Tuva and Vazquez Rueda, Omar and Silvermyr, David and Stenlund, Evert and Zurlo, N}},
  issn         = {{1029-8479}},
  keywords     = {{Hadron-Hadron scattering (experiments)}},
  language     = {{eng}},
  number       = {{4}},
  publisher    = {{Springer}},
  series       = {{Journal of High Energy Physics}},
  title        = {{Underlying event properties in pp collisions at √s = 13 TeV}},
  url          = {{http://dx.doi.org/10.1007/JHEP04(2020)192}},
  doi          = {{10.1007/JHEP04(2020)192}},
  volume       = {{2020}},
  year         = {{2020}},
}