P.E. Condon

Four-pion final state in pp annihilations at 0.7 to 1.1 GeV/c☆

Abstract Results are reported on the reaction p p → π + π + π − π − at six lab momenta spanning the region from 0.686 to 1.098 GeV/c. The cross section for this process drops from 5.2 ± 0.4 mb at 0.686 GeV/c to 2.9 ± 0.2 mb at 1.098 GeV/c. Resonance production is determined by means of a model which includes Bose symmetrization and Breit-Wigner amplitudes. The likelihood fit to the resonance channels yields a few per cent ϱππ, approximately 10% in each of the channels fππ, ϱϱ, and A2π, and about 40% ϱf production, with errors on the order of 5%. Excellent fits to the mass distributions are obtained. Essentially all production and decay angular distributions are found to be uniform, with only a few small deviations from isotropy reported. The angular correlations between like and unlike charged pion pairs are also found to be fit extremely well by the simple model of resonance production with Bose symmetrization.

Four-pion final state in p̄p annihilations at 940 MeV/c☆

Abstract Resilts are reported on the four-pion final state from antiproton annihilations in hydrogen in the vicinity of 940 MeV/ c . The cross section for π − π − π + π + is found to be 3.6 mb. Abundant resonance production is observed, with fits indicating that quasi-two-body production constitutes approximately half the four-pion events. The model employed, which includes resonance production and Bose symmetrization, yields excellent fits to mass distributions and angular correlations.

Analysis of pp → K+K− π+π− around 1 GeV/c

Approximately 100 000 four-prong antiproton annihilations in hydrogen were measured. A clean, unbiased sample of 842 K+K−π+π− events was obtained. This reaction is dominated by K∗(∼45%) and ϱ0(∼20%) production, with smaller amounts of A20(∼15%) and ϕ(∼5%) production. 25% of the reactions involved double resonance production. No significant three-body resonance production is observed.

Analysis of

Approximately 100 000 four-prong antiproton annihilations in hydrogen were measured. A clean, unbiased sample of 842 K+K−π+π− events was obtained. This reaction is dominated by K∗(∼45%) and ϱ0(∼20%) production, with smaller amounts of A20(∼15%) and ϕ(∼5%) production. 25% of the reactions involved double resonance production. No significant three-body resonance production is observed.