Seminário do Grupo de Hádrons e Física Teórica FEP
Data: Terça-Feira, 17 de Outubro de 2017.
Horário: 17:00.
Local: IFUSP, Edifício Principal, Ala 2, sala 335.
Título: Strangeness production in proton-proton collisions at the LHC
Palestrante: Dr. Rafael Derradi de Souza (UNICAMP).
Resumo da palestra:
Proton-proton (pp) collisions have been used extensively as a reference for the study of interactions of larger colliding systems like lead-lead (Pb-Pb). However, recent measurements performed in high-multiplicity pp and proton-lead (p-Pb) collisions have shown features that are reminiscent of those observed in Pb-Pb collisions. In particular, the study of the production rates of strange and multi-strange hadrons provides a valuable tool to probe changes in the underlying particle production mechanisms from small to large colliding systems.
In this talk we discuss the recent results reported by the ALICE Collaboration showing a progressive increase of the observed strange to non-strange hadron ratios as a function of the charged particle multiplicity at mid-rapidity in pp collisions at 7 TeV. The observed enhancement presents a hierarchy which seems to be driven by the number of strange quarks inside the hadron and cannot be satisfactorily reproduced by any QCD-inspired Monte Carlo generator currently in use at the LHC. Moreover, the observed trend seems to smoothly connect with the measurements performed in heavy-ion collisions, in which the strangeness enhancement has long been considered as a signature for the formation of a QGP phase. In addition, preliminary comparisons of measurements performed for pp collisions at 13 TeV show that the observed production rates are consistent with those observed at 7 TeV for similar charged particle multiplicities, suggesting that strangeness production does not depend on!
the collision energy but only on the multiplicity of the event.
