Identified particle production in pp collisions at = 7 and 13 TeV measured with ALICE

Abstract

Abstract. Proton-proton (pp) collisions have been used extensively as a reference for the study of interactions of larger colliding systems at the LHC. Recent measurements performed in high-multiplicity pp and proton-lead (p-Pb) collisions have shown features that are reminiscent of those observed in lead-lead (Pb-Pb) collisions. In this context, the study of identified particle spectra and yields as a function of multiplicity is a key tool for the understanding of similarities and differences between small and large systems. We report on the production of pions, kaons, protons, K 0 S , Λ, Ξ, Ω and K * 0 as a function of multiplicity in pp collisions at √ s = 7 TeV measured with the ALICE experiment. The work presented here represents the most comprehensive set of results on identified particle production in pp collisions at the LHC. Spectral shapes, studied both for individual particles and via particle ratios as a function of pT, exhibit an evolution with charged particle multiplicity that is similar to the one observed in larger systems. In addition, results on the production of light flavour hadrons in pp collisions at √ s = 13 TeV, the highest centre-of-mass energy ever reached in the laboratory, are also presented and compared with previous, lower energy results.

New insights into hadron production mechanism from pT spectra in pp collisions at s=7 Gou1, Shao2, Wang3 et al. 2017Phys. Rev. D222370View full textAdd to dashboardCite

“…From Fig. 6, we see that the spectrum shapes of proton, Λ, Ξ, Ω, and K(892) * 0 are in good agreement with the data [8,57]. Predictions of φ, Ξ * and Σ * + are presented.…”

“…High multiplicity means the high energy deposited in the collision region by the intense partonic interactions happening in early stage of collisions, which increases the possibility of the formation of the deconfined system. In deed, [8] and those of proton and K(892) * 0 are preliminary [57]. The data and our results in classes (II) and (III) are divided by factors 3 and 3 2 for clarity, respectively.…”

“…6. The data of Λ, Ξ and Ω − are from [8] and those of proton and K(892) * 0 are preliminary [57]. The fitted parameters for quark p T spectra (except a q = 0.05 GeV, b q = 0.5) and quark numbers are shown in Table II.…”

Multiplicity-dependent pT distributions of identified particles in pp collisions at 7 TeV within the HIJING/ BB¯Pop1, Petrovici2 2018Phys. Rev. C1000View full textAdd to dashboardCite

“…Shown in Fig. 2 are our theoretical calculations (open symbols) in comparison with data [68,69,71] on the p T of π + + π − , K + + K − , p +p, − +¯ + , and − + + for 0 < p T < 10 GeV/c and midrapidity |y| < 0.5 versus charged particle multiplicity N * ch (selected in the |η| < 0.5 range) for pp collisions at √ s = 7 TeV. The results (open symbols) are given for two values of the effective string tension κ = 2 GeV/fm (left panel) and κ = 5 GeV/fm (right panel).…”

“…The charged-particle densities dN ch /dη are integrated values at mid-pseudorapidity |η| < 0.5 for that class of events. The p T distributions of ID particles were recently measured in pp collisions at √ s = 7 TeV for different multiplicity classes of events by the ALICE Collaboration [68][69][70][71].…”