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

摘要

The study of identified particle production in proton-proton (pp) collisionsas a function of center-of-mass energy ($\sqrt{s}$) and event charged-particlemultiplicity is a key tool for understanding similarities and differencesbetween small and large collision systems. We report on new measurements of theproduction of identified particles and their dependence on multiplicity and$\sqrt{s}$. Latest results for light flavor hadrons, comprising $\pi^{\pm}$,$\mathrm{K}^{\pm}$, ${\rm p}(\rm \bar{p})$, single-strange($\mathrm{K_{S}^{0}}$, $\bar{\Lambda}$, and $\Lambda$), multi-strange($\Xi^{-}$, $\overline{\Xi}^{+}$, $\Omega^{-}$, and $\overline{\Omega}^{+}$)particles as well as resonances ($\mathrm{K^{*0}}$,$\mathrm{\overline{K}^{*0}}$, $\phi$), are presented for $\sqrt{s}~=~5.02, 7$,and 13 TeV. The measured minimum bias $p_{\rm T}$ spectra and yields werecomplemented with multiplicity-dependent measurements for single- andmulti-strange hadrons at $\sqrt{s}~=~7$ and $\sqrt{s}~=~13$ TeV. Results arecompared to measurements at lower $\sqrt{s}$ as well as to those in proton-leadand lead-lead (Pb-Pb) collisions, respectively at $\sqrt{s}_{\rm NN}~=~5.02$TeV and $\sqrt{s}_{\rm NN}~=~2.76$ TeV. The results unveil intriguingsimilarities among collision systems at different $\sqrt{s}$. The productionrates of strange hadrons are found to increase more than those of non-strangeparticles, showing an enhancement pattern with multiplicity which does notdepend on the collision energy. These yield ratios take values which are alikefor small systems at comparable multiplicities and show smooth evolution withmultiplicity across all collision systems. Although the multiplicity dependenceof spectral shapes can be qualitatively described by general-purpose MonteCarlo (MC) event generators, the evolution of yield ratios is barely (or not)captured by MC model predictions.