Probing the interplay of multiplicity and effective energy on strangeness production in pp collisions with ALICE

¹ INFN, Sezione di Bologna Bologna, Italy
² Dipartimento di Fisica, Università di Bologna Bologna, Italy

Published online: 6 November 2024

Abstract

The strong interaction between quarks and gluons, the elementary constituents of the hadronic matter, is described by quantum chromodynamics (QCD). Under extreme conditions of high temperature and energy density, the QCD predicts a transition from the hadronic phase to a colour deconfined medium called quark-gluon plasma (QGP). The QGP can be investigated in the laboratory through ultrarelativistic heavy-ion collisions, such as the ones between lead (Pb) ions at the Large Hadron Collider (LHC) at CERN. The enhanced production of strange hadrons in heavy-ion collisions with respect to proton-proton (pp) collisions was historically considered one of the signatures of QGP formation. At the LHC, the ALICE Collaboration observed that the ratio of strange to non-strange hadron yields increases with the charged-particle multiplicity at midrapidity, starting from pp collisions and evolving smoothly across larger interaction systems and energies, ultimately reaching Pb-Pb collisions. The origin of this effect in small collision systems remains an open question. This work exploits a novel approach to study strangeness production in pp collisions, introducing, for the first time, the concept of effective energy in hadronic collisions at the LHC.