New upper limits for H-particle production in p̄Xe annihilation at low energy

Abstract

A study of the reactions p Xe → K +K +X , p Xe → K +H(H → Σ −p)X and p Xe → K +K +H(H → Σ −p)X was performed using the 700-litre xenon bubble chamber DIANA, exposed to the 1 GeV/ c antiproton beam of ITEP (Moscow). From a sample of 7.8 · 10 5 antiproton annihilations at low energy in xenon nuclei 4 events were observed for the reaction p Xe| → K +K +X at rest ( P p ≤ 400 MeV/c ) and 8 for the same reaction in flight ( 400 ≤ P p ≤ 900 MeV/c ). The corresponding probabilities turned out to be 3.1 · 10 −5 and 3.4 · 10 −5, respectively. No H-event was found in the two semi-inclusive reactions p Xe → K +HX and p Xe → K +K +HX . This lead to the upper limits 6 · 10 −6 and 8 · 10 −6 (90% C.L.), respectively. The corresponding upper limit for the fully inclusive reaction p Xe → HX turned out to be 1.2 · 10 −5 (90% C.L.), which is about one order of magnitude lower than the actual value reported in the literature.