New Upper Limits for H-Particle Production in -pXe Annihilation at Low Energy

A study of the reactions Full-size image (<1 K), Full-size image (<1 K) and Full-size image (<1 K) 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 · 105 antiproton annihilations at low energy in xenon nuclei 4 events were observed for the reaction Full-size image (<1 K) at rest (Full-size image (<1 K)) and 8 for the same reaction in flight (Full-size image (<1 K)). 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 Full-size image (<1 K) and Full-size image (<1 K). 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 Full-size image (<1 K) 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.