${\mathrm{f}}_0(980)$ production in inelastic pp collisions at $\sqrt{s}=5.02$ TeV

Abstract

The measurement of the production of ${\mathrm{f}}_0(980)$ in inelastic pp collisions at $\sqrt{s}=5.02$ TeV is presented. This is the first reported measurement of inclusive ${\mathrm{f}}_0(980)$ yield at LHC energies. The production is measured at midrapidity, $|y|<0.5$, in a wide transverse momentum range, $0<p_{\mathrm{T}}<16$ GeV/$c$, by reconstructing the resonance in the ${\mathrm{f}}_0(980)\to {\pi }^{+}{\pi }^{-}$ hadronic decay channel using the ALICE detector. The $p_{\mathrm{T}}$-differential yields are compared to those of pions, protons and $\varphi$ mesons as well as to predictions from the HERWIG 7.2 QCD-inspired Monte Carlo event generator and calculations from a coalescence model that uses the AMPT model as an input. The ratio of the $p_{\mathrm{T}}$-integrated yield of ${\mathrm{f}}_0(980)$ relative to pions is compared to measurements in ${\mathrm{e}}^{+}{\mathrm{e}}^{-}$ and pp collisions at lower energies and predictions from statistical hadronisation models and HERWIG 7.2. A mild collision energy dependence of the ${\mathrm{f}}_0(980)$ to pion production is observed in pp collisions from SPS to LHC energies. All considered models underpredict the $p_{\mathrm{T}}$-integrated $2{\mathrm{f}}_0(980)/({\pi }^{+}+{\pi }^{-})$ ratio. The prediction from the canonical statistical hadronisation model assuming a zero total strangeness content of ${\mathrm{f}}_0(980)$ is consistent with the data within 1.9$\sigma$ and is the closest to the data. The results provide an essential reference for future measurements of the particle yield and nuclear modification in p$-$Pb and Pb$-$Pb collisions, which have been proposed to be instrumental to probe the elusive nature and quark composition of the ${\mathrm{f}}_0(980)$ scalar meson.

23 pages, 5 captioned figures, 1 table, authors from page 18, published version, figures at http://alice-publications.web.cern.ch/node/8276

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