Production of Σ⁰ Hyperons at LHC with ALICE

¹ Moscow Institute of Physics and Technology, Dolgoprudny, Russia
² National Research Nuclear University MEPhI, Moscow, Russia

^* e-mail: Alexander.Borissov@cern.ch

Published online: 19 November 2019

Abstract

The first measurements of the transverse momentum (pT) spectra and integrated yields of Σ⁰ and Σ⁻⁰ baryons in proton-proton (pp) collisions at √s = 7 TeV are reported. The Σ⁰(Σ⁻⁰) signal is reconstructed via the Λ (Λ⁻) + γ decay channel by invariant mass analysis. The Λ (Λ⁻) baryon is reconstructed by its weak decay into p + π⁻(p⁻ + π⁺), while the photon is detected exploiting the unique capability of the ALICE detector to measure low energy photons via conversion into e⁺e⁻ pairs. A significant disagreement between the data and the predictions from the QCD-inspired Monte Carlo event generator PYTHIA is observed for the pT spectrum. The yield ratio of Σ⁰(Σ⁻⁰) to Λ is shown as a function of pT . Finally, the new data point for the integrated yield ratio of Σ⁰(Σ⁻⁰) to Λ from pp collisions at 7 TeV is found to be similar to the results obtained in different elementary collison systems (e⁺e⁻, pp) measured at collision energies below 100 GeV.