Production of Σ ± Baryons in p–Pb and pp Collisions at the LHC with ALICE

This work presents novel measurements of charged Σ hyperons by the ALICE collaboration, with a particular emphasis on a new reconstruction technique for the decay channel Σ ± → n π ± . The core of our analysis is a pioneering method for detecting anti-neutrons using the photon spectrometer (PHOS). This approach overcomes the significant experimental challenge of reconstructing neutral particles by capitalizing on the characteristic hadronic showers produced by anti-neutrons upon annihilation in the electromagnetic calorimeter. The identification of the accompanying charged pion ( π ± ) completes the reconstruction of the Σ ± decay vertex. We report the transverse momentum ( p_T ) spectra of Σ ± hyperons in minimum bias pp and p–Pb collisions at √ s_NN = 5.02 TeV, the nuclear modification factor R_pPb , and Σ ⁺ 1pt / 1pt Σ ⁻ ratios. These results are compared with predictions from state-of-the-art Monte Carlo event generators to test their description of strangeness production.