Enhanced production of multi-strange hadrons in high-multiplicity proton-proton collisions
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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.
CitationAdam J, Adamová D, Aggarwal MM, Aglieri Rinella G, Agnello M, Agrawal N, Ahammed Z, Ahmad SF, Ahn SU, Aiola S, Alme J, Helstrup H, Hetland KF, Kileng B, Altinpinar S, Djuvsland Ø, Lønne P, Nystrand J, Rehman Au, Røhrich D, Tambave GJ, Ullaland K, Velure A, Wagner B, Zhang H, Zhou Z, Zhu H, Arsene IC, Bätzing P, Dordic O, Lindal S, Mahmood SM, Milosevic J, Qvigstad H, Richter M, Røed K, Skaali TB, Tveter TS, Wikne JC, Zhao C, Langøy R, Lien JA, Akindinov A, Alam SN, De Albuquerque DS, Aleksandrov D, Alessandro B, Alexandre D, Alfaro Molina JR, Alici A, ALICE C. Enhanced production of multi-strange hadrons in high-multiplicity proton-proton collisions. Nature Physics. 2017;13(6):535-539
PublisherNature Publishing Group
Copyright 2017 The Author(s)