Sigma_bar± production in pp and p−Pb collisions at √sNN = 5.02 TeV

Abstract

The transverse momentum spectra and integrated yields of anti-hyperons( ±) have been measured in pp and p−Pb collisions at√ sNN = 5.02TeVwiththeALICEexperiment. Measurements are performed via the newly accessed decay channel ±→ nπ±. A new method of antineutron reconstruction with the PHOS electromagnetic spectrometer is developed and applied to this analysis. The pT spectra of ± are measured in the range 0.5 < pT < 3GeV/c and compared to predictions of the PYTHIA 8, DPMJET, PHOJET, EPOS LHC and EPOS4 models. The EPOS LHC and EPOS4modelsprovidethebestdescriptionsofthemeasured spectra both in pp and p−Pb collisions, while models which do not account for multiparton interactions provide a considerably worse description at high pT. The total yields of ± in both pp and p−Pb collisions are compared to predictions of the Thermal-FIST model and dynamical models PYTHIA8,DPMJET,PHOJET,EPOSLHCandEPOS4.All models reproduce the total yields in both colliding systems within uncertainties. The nuclear modification factors RpPb for both + and − are evaluated and compared to those of protons, and hyperons, and predictions of EPOS LHC and EPOS4 models. No deviations of RpPb for ± from the model predictions or measurements for other hadrons are found within uncertainties.