φπ0 and φη production in antiproton 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 <(p)over bar p> --> phi pi(0) and <(p)over bar p> --> phi eta have been studied. The analysis of the angular distribution of the kaons emitted by the phi decay has shown that the reaction <(p)over bar p> --> phi pi(0) occurs essentially from S-3(1) states with a production rate R(NTP) = (2.46 +/- 0.23 +/- 0.07) x 10(-4), while the rate from P-1(1) states is compatible with zero. Because of acceptance limitations, S-3(1) and P-1(1) contributions to the reaction <(p)over bar p> --> phi eta could not be resolved and lower and upper limits for the production rate have been measured with the middle value R(NTP) = (0.87 +/- 0.21) x 10(-4). Also, for the phase-space K+ K- eta events the production rate R(NTP) = (4.67 +/- 0.35) x 10(-4) has been measured. The phi pi(0) K and phi eta branching ratios in S- and P-waves (defined in the text) have been estimated in a model dependent way. For the evaluation of the phi eta rate, a combination of our production rate and of data obtained with a liquid target has been used. The phi pi(0) production rate, compared to our preliminary value for the omega pi(0) production, confirms the strong violation of the OZI rule observed in other experiments. No violation is apparent in the phi eta production.