Production of light-flavor hadrons in pp collisions at $\sqrt{s}~=~7\text { and }\sqrt{s} = 13 \, \text { TeV} $

The ALICE collaboration
Eur.Phys.J.C 81 (2021) 256, 2021.

Abstract (data abstract)
The production of $\pi^{\pm}$, $\mathrm{K}^{\pm}$, $\mathrm{K_{S}^{0}}$, $\mathrm{K^{*}(892)^{0}}$, ${\rm p}$, ${\rm \overline{p}}$, $\phi(1020)$, $\Lambda$, $\overline{\Lambda}$, $\Xi^{-}$, $\overline{\Xi}^{+}$, $\Omega^{-}$, and $\overline{\Omega}^{+}$ was measured in inelastic proton--proton (pp) collisions at a center-of-mass energy of $\sqrt{s}=$ 13 TeV at midrapidity ($|y|<0.5$) as a function of transverse momentum ($p_{\mathrm{T}}$) using the ALICE detector at the CERN LHC. Furthermore, the single-particle $p_{\mathrm{T}}$ distributions of $\mathrm{K_{S}^{0}}$, $\Lambda$, and $\overline{\Lambda}$, in inelastic pp collisions at $\sqrt{s}=$ 7 TeV are reported here for the first time. The $p_{\mathrm{T}}$ distributions are studied at midrapidity within the transverse momentum range $0\leq p_{\mathrm{T}} \leq 20$ GeV/$c$, depending on the particle species. The $p_{\mathrm{T}}$ spectra, integrated yields, and particle yield ratios are discussed as a function of collision energy and compared with measurements at lower $\sqrt{s}$ and with results from various general-purpose QCD-inspired Monte Carlo models. A hardening of the spectra at high $p_{\mathrm{T}}$ with increasing collision energy is observed, which is similar for all particle species under study. The measured $p_{\mathrm{T}}$ spectra of mesons for $p_{\mathrm{T}}<2$ GeV/$c$ significantly deviate from the empirical transverse mass scaling relation based on the measured charged pion spectrum. The empirical $x_{\mathrm{T}}\equiv 2p_{\mathrm{T}}/\sqrt{s}$ scaling for $\pi^{\pm}$, $\mathrm{K}^{\pm}$, $\mathrm{K^{*0}}$ and ${\rm p}({\rm \overline{p}})$ is well satisfied in the hard scattering region of particle production. As the collision energy increases from $\sqrt{s}=$ 7 TeV to 13 TeV, the yields of non- and single-strange hadrons normalized to the pion yields remain approximately constant as a function of $\sqrt{s}$, while ratios for multi-strange hadrons indicate enhancements. The $p_{\mathrm{T}}$-differential cross sections of $\pi^{\pm}$, $\mathrm{K}^{\pm}$, and ${\rm p}({\rm \overline{p}})$ are compared with next-to-leading order perturbative QCD calculations, which are found to overestimate the cross sections for $\pi^{\pm}$ and ${\rm p}({\rm \overline{p}})$ at high $p_{\mathrm{T}}$.

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