Multi-strange baryon production in pp, p–Pb and Pb–Pb collisions measured with ALICE

Dipartimento Interateneo di Fisica “M. Merlin” and Sezione INFN, Via Orabona 4, 70126 Bari, Italy

^a e-mail: domenico.colella@cern.ch

Published online: 24 November 2014

Abstract

The production of Ξ⁻ and Ω⁻ baryons and their anti-particles in pp, p–Pb and Pb–Pb collisions has been measured by the ALICE Collaboration. These hyperons are reconstructed via the detection of their charged weak-decay products, which are identified through their measured ionisation losses and momenta in the ALICE Time Projection Chamber. Comparing the production yields in Pb–Pb and pp collisions, a strangeness enhancement has been measured and found to increase with the centrality of the collision and with the strangeness content of the baryon; moreover, in the comparison with similar measurements at lower energies, it decreases as the centre-of-mass energy increases, following the trend already observed moving from SPS to RHIC. Recent measurement of cascade and Ω in p–Pb interactions are compared with results in Pb–Pb and pp collisions and with predictions from thermal models, based on a grand canonical approach. The nuclear modification factors for the charged Ξ and Ω, compared to the ones for the lighter particles, are also presented.