PHI-PI(0) AND PHI-ETA 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 NT P have been collected with the Obelix spectrometer exposed to the beam extracted from the LEAR accelerator of CERN. The reactions <(p)over b ar 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) oc curs 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 n ot 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 ph i eta branching ratios in S- and P-waves (defined in the text) have be en estimated in a model dependent way. For the evaluation of the phi e ta rate, a combination of our production rate and of data obtained wit h a liquid target has been used. The phi pi(0) production rate, compar ed to our preliminary value for the omega pi(0) production, confirms t he strong violation of the OZI rule observed in other experiments. No violation is apparent in the phi eta production.