New data on OZI rule violation in bar{p}p annihilation at rest

The results of a measurement of the ratio R = Y(phi pi+ pi-) / Y(omega pi+ pi-) for antiproton annihilation at rest in a gaseous and in a liquid hydrogen target are presented. It was found that the value of this ratio increases with the decreasing of the dipion mass, which demonstrates the difference in the phi and omega production mechanisms. An indication on the momentum transfer dependence of the apparent OZI rule violation for phi production from the 3S1 initial state was found.Comment: 11 pages, 3 PostScript figures, submitted to Physics Letter

Antiproton stopping power in He in the energy range 1–900 keV and the Barkas effect

AbstractThe p¯ stopping power in helium from 1 keV kinetic energy is evaluated. Contrary to the effect observed around and below the maximum, Obelix data indicate a p¯ stopping power higher than that for proton, the difference being of the order of 15±5% at ≈700 keV. The result contributes to assert the fundamental difference between p¯ stoppings in the simplest gases (He, H2) and in solid targets below some MeV

Protonium annihilation into π0π0 at rest in a liquid hydrogen target

The annihilation frequency of the reaction p¯ p!p0p0 at rest in liquid hydrogen has been measured by the Obelix experiment by using different apparatus configurations and trigger conditions. The value obtained is f (p0p0, LH)5(2.860.1stat60.4syst)31024. With the same data samples, the p0h annihilation frequency has been determined to be f (p0h, LH)5(0.960.2stat60.1syst)31024. The results are discussed within the frame of the present experimental situation

Results of the coupled channel analysis of π+π−π0, K+K−π0 and K±K0Sπ∓ final states from p̄p annihilation at rest in hydrogen targets at different densities

n/