Regular Article - Theoretical Physics
Impact of Baryon anti-Baryon annihilation on hyperon (, ) production and apparent strangeness enhancement in in heavy ion collisions at SPS energy
Variable Energy Cyclotron Centre, 1/AF, Bidhan Nagar, 700064, Kolkata, India
2 Homi Bhabha National Institute, 400094, Mumbai, India
Accepted: 12 October 2022
Published online: 19 October 2022
A deconfined medium of quarks and gluon, called the Quark–Gluon Plasma (QGP) is produced when heavy-nuclei are collided at relativistic energies. The QGP formation is often characterized by a phenomenon called strangeness enhancement where, the relative production of strange-to-non-strange particles are enhanced in central collisions compared to peripheral or proton-proton interactions. Besides the enhancement in K/ ratios, a non-monotonic energy dependence was also reported for to ratios at CERN SPS, attributed to a signature for the strangeness enhancement as well. As anti-particles are produced directly from the reaction, the / ratios are considered as a cleaner probe for the strangeness enhancement. However, at this energy range hadronic interactions have a dominant role to play and, importantly for and , processes like baryon-anti-baryon () annihilation can have a significant impact. In this work, we use a hadronic transport model UrQMD, to investigate the role of baryon-anti-baryon () annihilation on , hyperon production and its effect on / ratios. The UrQMD calculations that include annihilation can produce the trend of average transverse mass spectra for and , as well as, the characteristic enhancement in / ratios in data as a function of centrality and collision energy. Furthermore, / ratios extracted from the feed-down corrected SPS data are seen to be in good agreement with UrQMD model calculations with annihilation. This suggests that / enhancement is not necessarily because of strangeness enhancement and annihilation has a significant role to play.
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