Using Ξ(1820) baryons to test for parity doubling at ALICE

We investigate the production of Ξ(1820) baryons in pp collisions at 13 TeV by reconstructing their Λ-Κ decays. Recent lattice calculations on parity doubling indicate that the masses of negative-parity particles, such as Ξ(1820), may decrease at high temperatures, while the masses of positive-parity partners, i.e. the Ξ(1530), do not. Furthermore, the lifetime of the Ξ(1820) is short enough that it may be suppressed in high-multiplicity collisions, as has been observed for Λ(1520), K*(892), and ρ(770). Studying Ξ(1820) also allows us to better understand the spectrum of excited hyperon states, with implications for our understanding of the hadron resonance gas. Using ALICE data from 2015-2018, we have reconstructed the Ξ(1820) and measured its mass, width, and yield as functions of transverse momentum and collision multiplicity. The mass and width measurements are in general agreement with previous measurements, but could indicate a slight increase in the width as a function of charged particle multiplicity. These pp studies will inform future studies of the Ξ(1820) in p-Pb and Pb-Pb collisions.