Production of $\Sigma^0$ Hyperons at LHC with ALICE

The first measurements of the transverse momentum ($p_T$) spectra and integrated yields of $\Sigma^0$ and $\overline{\Sigma}^0$ baryons in proton-proton (pp) collisions at $\sqrt{s}$ = 7 TeV are reported. The $\Sigma^0$ ($\overline{\Sigma}^0$) signal is reconstructed via the $\Lambda$ ($\overline{\Lambda}$) + $\gamma$ decay channel by invariant mass analysis. The $\Lambda$ ($\overline{\Lambda}$) baryon is reconstructed by its weak decay into $\mathrm{p} + \pi^-(\overline{\mathrm{p}}$ + $\pi^+$), while the photon is detected exploiting the unique capability of the ALICE detector to measure low energy photons via conversion into e$^+$e$^- $ pairs. A significant disagreement between the data and the predictions from the QCD-inspired Monte Carlo event generator PYTHIA is observed for the $p_T$ spectrum. The yield ratio of $\Sigma^0$ ($\overline{\Sigma}^0$) to $\Lambda$ is shown as a function of $p_T$ . Finally, the new data point for the integrated yield ratio of $\Sigma^0$ ($\overline{\Sigma}^0$) to $\Lambda$ from pp collisions at 7 TeV is found to be similar to the results obtained in different elementary collison systems (e$^+$e$^- $, pp) measured at collision energies below 100 GeV.