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The strangeness production has been widely studied through measurements of kaons, $\Lambda$, $\Xi$ and $\Omega$ baryons from small to large collision systems. However, a strange baryon has not been fully studied yet - the $\Sigma$ baryon. $\Sigma$ baryons contain a single strange quark and form a triplet, with the charge (+, 0, -) depending on the light quark content. However, the experimental measurement is a challenging task. Only $\Sigma^{0}$ in 7 TeV pp collisions have been measured by ALICE, while few other experiments have measured the charged states at lower pp($\rm p \bar{p}$) collision energies.
During the LHC Run 2 several methods to identify charged $\Sigma$ have been developed by ALICE. The decay $\Sigma^{+} \rightarrow p +\pi^{0}$ can be reconstructed via the direct detection of the proton and the two gammas from the $\pi^{0}$ decay. Gamma can be also identified via conversion into $\rm e^{+}e^{-}$ pairs.
The latest addition is a method to detect anti-neutrons in the Photon Spectrometer (PHOS), allowing the $\bar{\Sigma}^{\pm} \rightarrow \bar{n} + \pi^{\pm}$ decays to be reconstructed. We present the transverse momentum spectra of $\Sigma^{+}$ and its charge conjugate anti-particle, in both minimum bias and high-multiplicity triggered pp collisions at $\sqrt{s} = 13$ TeV, $\bar{\Sigma}^{\pm}$ spectra in pPb and pp collisions at $\sqrt{s} = 5.02$ TeV and $\Sigma^{0}$ spectrum in 7 TeV pp collisions, compared with predictions from state-of-the-art Monte Carlo models. In addition, integrated yields are compared with Thermal model predictions.
| Section | Heavy ion collisions at Intermediate and high energies |
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