Σ Hyperons Production in pp and p-Pb Collisions at LHC with ALICE

In addition to $$\Lambda $$ hyperons, new data on $$\Sigma $$ hyperons production are compared to different Monte-Carlo models and contribute to understand hadron production mechanisms. The first measurements of the transverse momentum ( $${{p}_{{\text{T}}}}$$ ) spectra of $${{\Sigma }^{0}}$$ and $${{\overline \Sigma }^{0}}$$ hyperons in pp collisions at $$\sqrt s = 7$$ TeV at the LHC are presented. The $${{\Sigma }^{0}}$$ ( $${{\overline \Sigma }^{0}}$$ ) is reconstructed via its electromagnetic decay channel $$\Lambda (\overline \Lambda ) + \gamma $$ , while the $$\Lambda $$ ( $$\overline \Lambda $$ ) baryon is detected via its decay into $$p + {{\pi }^{ - }}$$ ( $$\bar {p}$$ + $${{\pi }^{ + }}$$ ). The low-energy photon is measured via conversion into $${{e}^{ + }}{{e}^{ - }}$$ pairs in the detector material and in PHOS calorimeter by exploiting the unique capability of the ALICE detector. The complementary results on the first detection of $${{\Sigma }^{ + }}$$ and $${{\overline \Sigma }^{ - }}$$ hyperon at the LHC with ALICE are shown in pp collisions at $$\sqrt s = 13$$ TeV. The $${{\Sigma }^{ + }}$$ ( $${{\overline \Sigma }^{ - }}$$ ) is reconstructed via its weak decay into p $$(\bar {p}) + {{\pi }^{0}}$$ with the challenging detection of low-energy photons from $${{\pi }^{0}}$$ decay. Also, the first reconstruction of $${{\overline \Sigma }^{ \pm }} \to \bar {n} + {{\pi }^{ \pm }}$$ decays and $${{\overline \Sigma }^{ \pm }}$$ transverse momenta spectra in pp and p-Pb collisions are presented. Antineutron is identified and reconstructed with PHOS by unique signature of the annihilation process.