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Observation of partonic flow in proton—proton and proton—nucleus collisions

Acharya, S. ; Basu, S. LU orcid ; Christiansen, P. LU ; Hansen, J. LU orcid ; Iversen, K.E. LU orcid ; Nepeivoda, R. LU orcid ; Ohlson, A. LU ; Panasenko, I. LU ; Silvermyr, D. LU orcid and Staa, J. LU , et al. (2026) In Nature Communications 17(1).
Abstract
Quantum Chromodynamics predicts a phase transition from hadronic matter to quark–gluon plasma (QGP) at high temperatures and energy densities, where quarks and gluons (partons) are no longer confined within hadrons. The QGP forms in ultrarelativistic heavy-ion collisions. Anisotropic flow coefficients, quantifying the azimuthal expansion of produced matter, probe QGP properties. Flow measurements in high-energy heavy-ion collisions show a distinctive grouping of anisotropic flow for baryons and mesons at intermediate transverse momentum – a feature associated with flow imparted at the quark level, confirming QGP existence. The observation of QGP-like features in proton–proton and proton–ion collisions has sparked debate about QGP formation... (More)
Quantum Chromodynamics predicts a phase transition from hadronic matter to quark–gluon plasma (QGP) at high temperatures and energy densities, where quarks and gluons (partons) are no longer confined within hadrons. The QGP forms in ultrarelativistic heavy-ion collisions. Anisotropic flow coefficients, quantifying the azimuthal expansion of produced matter, probe QGP properties. Flow measurements in high-energy heavy-ion collisions show a distinctive grouping of anisotropic flow for baryons and mesons at intermediate transverse momentum – a feature associated with flow imparted at the quark level, confirming QGP existence. The observation of QGP-like features in proton–proton and proton–ion collisions has sparked debate about QGP formation in smaller systems. For the first time, we demonstrate the distinctive grouping of anisotropic flow for baryons and mesons in high-multiplicity proton–lead and proton–proton collisions at the Large Hadron Collider (LHC). These results are described by a model including hydrodynamic flow followed by hadron formation via quark coalescence, consistent with the formation of partonic flowing systems in these collisions. © The Author(s) 2026. (Less)
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organization
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type
Contribution to journal
publication status
published
subject
keywords
proton, coalescence, collision, hydrodynamics, momentum, phase transition, plasma, Article, gluon, hadron, high temperature, quark
in
Nature Communications
volume
17
issue
1
article number
2585
publisher
Nature Publishing Group
external identifiers
  • scopus:105033887255
  • pmid:41862434
ISSN
2041-1723
DOI
10.1038/s41467-025-67795-1
language
English
LU publication?
yes
id
2ea93dff-379b-4645-be8b-720d8ec966e9
date added to LUP
2026-07-02 10:50:55
date last changed
2026-07-03 03:24:21
@article{2ea93dff-379b-4645-be8b-720d8ec966e9,
  abstract     = {{Quantum Chromodynamics predicts a phase transition from hadronic matter to quark–gluon plasma (QGP) at high temperatures and energy densities, where quarks and gluons (partons) are no longer confined within hadrons. The QGP forms in ultrarelativistic heavy-ion collisions. Anisotropic flow coefficients, quantifying the azimuthal expansion of produced matter, probe QGP properties. Flow measurements in high-energy heavy-ion collisions show a distinctive grouping of anisotropic flow for baryons and mesons at intermediate transverse momentum – a feature associated with flow imparted at the quark level, confirming QGP existence. The observation of QGP-like features in proton–proton and proton–ion collisions has sparked debate about QGP formation in smaller systems. For the first time, we demonstrate the distinctive grouping of anisotropic flow for baryons and mesons in high-multiplicity proton–lead and proton–proton collisions at the Large Hadron Collider (LHC). These results are described by a model including hydrodynamic flow followed by hadron formation via quark coalescence, consistent with the formation of partonic flowing systems in these collisions. © The Author(s) 2026.}},
  author       = {{Acharya, S. and Basu, S. and Christiansen, P. and Hansen, J. and Iversen, K.E. and Nepeivoda, R. and Ohlson, A. and Panasenko, I. and Silvermyr, D. and Staa, J. and Zurlo, N.}},
  issn         = {{2041-1723}},
  keywords     = {{proton; coalescence; collision; hydrodynamics; momentum; phase transition; plasma; Article; gluon; hadron; high temperature; quark}},
  language     = {{eng}},
  number       = {{1}},
  publisher    = {{Nature Publishing Group}},
  series       = {{Nature Communications}},
  title        = {{Observation of partonic flow in proton—proton and proton—nucleus collisions}},
  url          = {{http://dx.doi.org/10.1038/s41467-025-67795-1}},
  doi          = {{10.1038/s41467-025-67795-1}},
  volume       = {{17}},
  year         = {{2026}},
}