Multiplicity and rapidity dependence of strange hadron production in pp, pPb, and PbPb collisions at the LHC

Abstract

Measurements of strange hadron (View the MathML sourceKS0, View the MathML sourceΛ+Λ‾, and View the MathML sourceΞ−+Ξ‾+) transverse momentum spectra in pppp, pPbpPb, and PbPb collisions are presented over a wide range of rapidity and event charged-particle multiplicity. The data were collected with the CMS detector at the CERN LHC in pppp collisions at View the MathML sources=7TeV, pPbpPb collisions at View the MathML sourcesNN=5.02TeV, and PbPb collisions at View the MathML sourcesNN=2.76TeV. The average transverse kinetic energy is found to increase with multiplicity, at a faster rate for heavier strange particle species in all systems. At similar multiplicities, the difference in average transverse kinetic energy between different particle species is observed to be larger for pppp and pPbpPb events than for PbPb events. In pPbpPb collisions, the average transverse kinetic energy is found to be slightly larger in the Pb-going direction than in the p-going direction for events with large multiplicity. The spectra are compared to models motivated by hydrodynamics

Production of single-charm hadrons by the quark-combination mechanism in p -Pb collisions at sNN=5.02 TeV

“…This is somewhat puzzling. For light-flavor hadrons, the ratios of baryons to mesons such as p/π and Λ/K 0 s yield ratios at LHC energies are relatively stable at different system sizes and in different rapidity regions [8,48,51,52,63,64]. Models or event generators based on string or cluster fragmentation also usually predict the stable baryon/meson yield ratios as the function of rapidity [19,21,57].…”

Experimental overview on small collision systems at the LHC

“…Low p T spectra ("radial flow") yes yes yes [37][38][39][40][41][42] Intermed. p T ("recombination") yes yes yes [41][42][43][44][45][46][47]…”

New results on the multiplicity and centre-of-mass energy dependence of identified particle production in pp collisions with ALICE

“…Recent results on particle production at the LHC obtained in high-multiplicity proton-proton (pp) and proton-lead (p-Pb) collisions revealed phenomena which are similar to those seen in Pb-Pb collisions where they are attributed to bulk collective effects [1,2]. Apart from the peculiar patterns seen in two-particle azimuthal correlations [3,4], notably, some of these observations are the radial flow signals [5,6] and the strangeness enhancement [7,8]. Strangeness enhancement with respect to minimum bias (MB) pp collisions historically has been proposed as a signature of Quark-Gluon Plasma (QGP) formation [9].…”