Observation of Ξ− production in pp interactions at 540 GeV CMS energy

Abstract We have made the first observations of Ξ − production in p p interactions at √ s =540 GeV. In a sample of 6964 non single-diffractive events we observe 17 Ξ − decays with an estimated background of less than one event. This corresponds to 0.04 ± 0.01 Ξ − per event in the transverse momentum range p t >1.0 GeV/ c and in the pseudorapidity range |η| p t distribution, we find 〈 p t 〉=1.1 −0.2 +0.3 GeV/ c .