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 observed(2-6). Strangeness enhancement, originally proposed as a signature of QGP formation in nuclear collisions(7), is more pronounced for multi-strange baryons. Several effects typical of heavy-ion phenomenology have been observed in high-multiplicity proton-proton (pp) collisions(8,9), 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 results(10,11), 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.
Enhanced production of multi-strange hadrons in high-multiplicity proton-proton collisions / Adam, J; Adamov, D.; Aggarwal, M.; Rinella, G.; Agnello, M.; Agrawal, N.; Ahmmed, Z.; Ahn, S.; Bufalino, S.; Ravasenga, I.. - In: NATURE PHYSICS. - ISSN 1745-2473. - STAMPA. - 13:6(2017), pp. 535-539. [10.1038/nphys4111]
|Titolo:||Enhanced production of multi-strange hadrons in high-multiplicity proton-proton collisions|
|Data di pubblicazione:||2017|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1038/nphys4111|
|Appare nelle tipologie:||1.1 Articolo in rivista|
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