Phi pi0 and Phi eta production in anti-proton annihilation at rest in a hydrogen gas target at NTP

Data of antiproton annihilation at rest in a hydrogen gas target at NTP have been collected with the Obelix spectrometer exposed to the beam extracted from the LEAR accelerator of CERN. The reactions pbar p --> Phi pi0 and Phi Eta have been studied. The analysis of the angular distribution of the kaons emitted by the ~b decay has shown that the reaction ~p ~ ¢~" 0 occurs essentially from 3S 1 states with a production rate RrcrP = (2.46 ___ 0.23 _ 0.07) x 10 -4, while the rate from 1P 1 states is compatible with zero. Because of acceptance limitations, 3S 1 and 1p1 contributions to the reaction ~p ~ ~br/could not be resolved and lower and upper limits for the production rate have been measured with the middle value Rm. P = (0.87 + 0.21) x 10 -4. Also, for the phase-space K+K-r/ events the production rate RN~ = (4.67 ___ 0.35) × 10 -4 has been measured. The thTr ° and th*/branching ratios in S- and P-waves (defined in the text) have been estimated in a model dependent way. For the evaluation of the ~b~/ rate, a combination of our production rate and of data obtained with a liquid target has been used. The ~b~r ° production rate, compared to our preliminary value for the to~ -° production, confirms the strong violation of the OZI rule observed in other experiments. No violation is apparent in the PhiEta production.