Hyperon production in p-Pb collisions with ALICE at the LHC

[摘要] This thesis discusses the production of the multi-strange, charged Ξ and Ω baryons in proton-lead (p-Pb) collisions at a centre-of-mass energy of 5.02 TeV. The transverse momentum, P\(_T\), distributions are analysed as a function of event multiplicity. A hydrodynamical model based on statistical physics reproduces the shapes of the multi-strange p\(_T\)spectra, in conjunction with the spectra of lighter hadrons, in high multiplicity data. The good agreement is an indication of collective behaviour by all particles inside a system in thermal equilibrium, consistent with the picture of the build {up of a radially outward expansion due to an initially dense medium. These results are reminiscent of the observations made in lead-lead (Pb-Pb) collisions, which are explained by the formation of a Quark-Gluon Plasma. In addition, the p\(_T\)-integrated yields of the hyperons are reported on, revealing a steady increase as a function of multiplicity. An enhancement with respect to non-strange hadrons is observed, and the Ξ/π and Ω/π ratios in high multiplicity p-Pb data approach those measured in central Pb-Pb collisions. The Ξ/π ratio is comparable with the calculations from a thermal model for strangeness saturation, whereas the Ω/π ratio deviates from that value by 2σ.

[发布机构] University:University of Birmingham;Department:School of Physics and Astronomy

[关键词] Q Science;QC Physics