p p annihilation cross sections into 2-, 4- and 6-prong topologies, and the exclusive annihilation cross sections for the π + π − , K + K − , π + π − π 0 , π + π + π − π − , π + π + π − π − π 0 , π + π + π + π − π − π − , and π + π + π + π − π − π − π 0 channels in the momentum range 374–680 MeV/ c were measured. No prominent structure was observed in the momentum dependence of any of the above cross sections, but a small enhancement in the cross section was observed at 490 MeV/ c corresponding to the S meson mass in the topological, and π + π − π 0 and π + π + π − π − π 0 cross sections. If the extensive of the S meson with a mass and width of 1935.5 and 2.8 MeV/ c 2 is assumed, our measurement gives a total resonant annihilation cross section into charged particles of 10.0±3.0 mb.
FIRST CROSS SECTION IS CHARGED ANNIHILATION CROSS SECTION AND IS THE SUM OF THE 2, 4, AND 6PRONG.
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The elastic and inelastic\(\bar p\)p cross sections at 70 GeV/c have been determined in an experiment performed at CERN using BEBC equipped with a TST. The topological cross sections were measured and the moments of the inelastic multiplicity distribution are 〈nc〉=6.16±0.09, 〈nc〉/D=2.04±0.05 andf2cc=2.97±0.03. The average number of Dalitz pairs per inelastic event is (3.12±0.09)×10−2. Assuming that these all arise from π0 decay the average π0 multiplicity is\(\langle n_{\pi ^0 } \rangle= 2.71 \pm 0.14\). The\(\bar p\)p−pp cross section differences lead to an annihilation cross section σA = 4.42±0.41 mb and the moments of the annihilation multiplicty distribution are 〈nA〉=8.0±0.3, 〈nA〉/D=2.5±0.2 andf2A−−=−1.4±0.3. An independent check of σA was made by investigating fast forward charged and neutral secondary interactions in the TST and in the surrounding neon-hydrogen mixture, and gives a value σA = 5.0±1.6 mb. The ratio of fast\(\bar n\) to\(\bar p\) production in non-annihilation interactions at 70 GeV/c is found to be 0.45±0.11.
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INELASTIC TOPOLOGICAL CROSS SECTIONS. NORMALIZED TO TOTAL INELASTIC CROSS SECTION OF 35.7 +- 0.5 MB (AYRES ET AL., PR D15, 3105).
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