Measurements of the reaction p̄p→φη of antiproton annihilation at rest at three hydrogen target densities

Abstract

Measurements of the reactionpp → φη of antiproton annihilation at rest at three hydrogen target densitiesThe OBELIX Collaboration. AbstractThepp annihilation at rest into the φη final state was measured for three different target densities: liquid hydrogen, gaseous hydrogen at NTP and at a low pressure of 5 mbar. The yield of this reaction in the liquid hydrogen target is smaller than in the low-pressure gas target. The branching ratios of the φη channel were calculated on the basis of simultaneous analysis of the three data samples. The branching ratio for annihilation into φη from the 3 S 1 protonium state turns out to be about ten times smaller as compared to the one from the 1 P 1 state.

Loop calculations and OZI rule

“…The experiments performed at LEAR (see [5][6][7][8][9][10][11][12][13][14][15] and references therein) have demonstrated, in agreement with earlier findings [16], that the OZI rule is strongly violated in several channels in pp annihilation at low energy. To explain these results two different theoretical approaches have been used.…”

“…The relative strength of the φ peak depends sensitively on the corresponding ratio β which reflects the properties of the pp → KKη amplitude. Its dependence on the initial pp state can be a reason for the strong difference between the branching ratios BR(pp(L) → φη) for the S and P -states seen in recent OBELIX data [13].…”

Polarized strangeness in the nucleon

“…The rearrangement nature of additional φ production allows to make some interesting prediction concerning annihilation into the φη final state. This channel was measured by the OBELIX collaboration [25] for thepp annihilation at rest in liquid hydrogen, gas at NTP and at low pressure of 5 mbar. The φη final state has the same J P C as the φπ 0 final state.…”