Enhanced production of multi-strange hadrons in high-multiplicity proton–proton collisions

By J. Adam, D. Adamová, M. Aggarwal, G. Rinella, M. Agnello, N. Agrawal, Z. Ahammed, S. Ahmad, S. Ahn, S. Aiola and 985 more. Nature Physics, 2016

681 citations recorded by the source corpus.

Quark–gluon plasma is an exotic state of matter that can emerge in heavy nuclei high-energy collisions. The ALICE collaboration reports the first observation of strangeness enhancement in proton–proton collisions, a possible signature of this state. At sufficiently high temperature and energy density, nuclear matter undergoes a transition to a phase in which quarks and gluons are not confined: the quark–gluon plasma (QGP)1. Such an exotic state of strongly interacting quantum chromodynamics matter is produced in the laboratory in heavy nuclei high-energy collisions, where an enhanced production of strange hadrons is observed2,3,4,5,6. Strangeness enhancement, originally proposed as a signature of QGP formation in nuclear collisions7, is more pronounced for multi-strange baryons. Several effects typical of heavy-ion phenomenology have been observed in high-multiplicity proton–proton (pp) collisions8,9, but the enhanced production of multi-strange particles has not been reported so far. Here we present the first observation of strangeness enhancement in high-multiplicity proton–proton collisions. We find that the integrated yields of strange and multi-strange particles, relative to pions, increases significantly with the event charged-particle multiplicity. The measurements are in remarkable agreement with the p–Pb collision results10,11, indicating that the phenomenon is related to the final system created in the collision. In high-multiplicity events strangeness production reaches values similar to those observed in Pb–Pb collisions, where a QGP is formed.

Subfields: Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/e8bc737e077e6f4fb5cffb2701ba08cf20d4d85f

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Citations in the corpus

Small System Collectivity in Relativistic Hadronic and Nuclear Collisions (2018, background): “Recent measurements of strangeness enhancement of multi-strange baryons in p+ p collisions at the LHC have revived this important discussion (15).”
Open Questions in Cosmic-Ray Research at Ultrahigh Energies (2019, positive): “LHC data show that proton-proton interactions of high multiplicity exhibit features previously only seen in heavy ion collisions (see e.g., Khachatryan et al., 2010; Aad et al., 2016c; Adam et al., 2017).”
The Muon Puzzle in cosmic-ray induced air showers and its connection to the Large Hadron Collider (2021, methodology): “The potential key to the Muon Puzzle was discovered by the ALICE collaboration, which found a universal strangeness and baryon enhancement in p-p, p-Pb and Pb-Pb (Abelev et al. 2014b; Adam et al. 2016c, 2017b; Vasileiou 2020).”
Relativistic Fluid Dynamics in and out of Equilibrium (2017, background): “Moreover, other experimental signatures such as strangeness enhancement – traditionally expected to occur only in heavy-ion collisions – have been observed in protonproton collisions [408].”
The Angantyr model for heavy-ion collisions in Pythia8 (2018, background): “[34] we showed that overlapping strings forming ”ropes” can reproduce the increased strangeness in pp [7], as well as in pPb and PbPb [80] collisions.”
Multiplicity dependence of light-flavor hadron production in pp collisions at √s = 7 TeV (2019, background): “The data presented in [12] show for the first time that there is a continuous increase of strangeness production with increasing event multiplicity across various collision systems.”