(Σ)over-bar± production in pp and p-Pb collisions at √sNN=5.02 TeV with ALICE

Abstract

The transverse momentum spectra and integrated yields of anti-Sigma hyperons ((Sigma) over bar (+/-)) have been measured in pp and p-Pb collisions at root s(NN) = 5.02 TeV with the ALICE experiment. Measurements are performed via the newly accessed decay channel (Sigma) over bar (+/-) -> (n) over bar pi(+/-). A new method of antineutron reconstruction with the PHOS electromagnetic spectrometer is developed and applied to this analysis. The p(T) spectra of (Sigma) over bar (+/-) are measured in the range 0.5 < p(T) < 3 GeV/c and compared to predictions of the PYTHIA 8, DPMJET, PHOJET, EPOS LHC and EPOS4 models. The EPOS LHC and EPOS4 models provide the best descriptions of the measured spectra both in pp and p-Pb collisions, while models which do not account for multiparton interactions provide a considerably worse description at high p(T). The total yields of (Sigma) over bar (+/-) in both pp and p-Pb collisions are compared to predictions of the Thermal-FIST model and dynamical models PYTHIA 8, DPMJET, PHOJET, EPOS LHC and EPOS4. All models reproduce the total yields in both colliding systems within uncertainties. The nuclear modification factors R-pPb for both (Sigma) over bar (+) and (Sigma) over bar (-) are evaluated and compared to those of protons, Lambda and Xi hyperons, and predictions of EPOS LHC and EPOS4 models. No deviations of R-pPb for (Sigma) over bar (+/-) from the model predictions or measurements for other hadrons are found within uncertainties.