Measurements of $Xi^{-}$ and $ar{Xi}^+$ production in proton-proton interactions at $sqrt{S}_{NN} = 17.3 GeV$ in the NA61/SHINE experiment

The production of Xi (1321)- and Xi (1321)+ hyperons in inelastic p+p interactions is studied in a fixed target experiment at a beam momentum of 158 Ge/c. Double differential distributions in rapidity y and transverse momentum pT are obtained from a sample of 33M inelastic events. They allow to extrapolate the spectra to full phase space and to determine the mean multiplicity of both Xi- and Xi +. The rapidity and transverse momentum spectra are compared to transport model predictions. The Xi - mean multiplicity in inelastic p+p interactions at 158 Ge/c is used to quantify the strangeness enhancement in A+A collisions at the same centre-of-mass energy per nucleon pair.