Study of pi+ p four prong interactions from 2.95-GeV/c to 4.08-GeV/c

Brown, David ; Gidal, George ; Birge, Robert W. ; et al.
Phys.Rev.D 1 (1970) 3053, 1970.
Inspire Record 74876 DOI 10.17182/hepdata.25065

In a study of the production mechanism of quasi-two-body final states at the five incident π+ momenta 2.95, 3.2, 3.5, 3.75, and 4.08 GeV/c, approximately 40 000 events with four outgoing charged particles were investigated. The cross sections for the processes π+p→N*++ρ, π+p→N*++ω, π+p→N*++η, and π+p→N*++f have been measured as a function of the pion energy. The differential cross sections and the decay density-matrix elements are discussed in terms of one-meson-exchange models [with absorption (OPEA) and with form factor (OPEW)] and Regge models. For the N*++ρ and the N*++ω reactions, the joint-decay matrix elements are calculated. The formation of N*(2850) in the direct channel is also investigated.

30 data tables

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VAN HOVE ANALYSIS OF THE REACTIONS pi- p ---> pi- pi- pi+ p AND pi+ p ---> pi+ pi+ pi- p AT 16-GeV/c

Ballam, Joseph ; Chadwick, G.B. ; Guiragossian, Zaven G.T. ; et al.
Phys.Rev.D 4 (1971) 1946, 1971.
Inspire Record 67149 DOI 10.17182/hepdata.23179

Data from the reactions π−p→π−π−π+p and π+p→π+π+π−p have been obtained at 16 GeV/c in approximately equal samples from the BNL 80-in. hydrogen bubble chamber. We have studied both reactions for resonance production and compared our results with predictions of the one-pion-exchange model (OPEM) calculated by Wolf. The four-body longitudinal phase-space (LPS) plot suggested by Van Hove was used to analyze the data from both reactions. The events were separated according to distinct regions of the LPS plot in order to study the following classes of quasi-two-body final states: (1) diffractively produced three-pion states, (2) diffractively produced ππp states, (3) double-resonance production such as ρ0Δ++, (4) single-resonance production such as π−π−Δ++. The Van Hove analysis provided a much cleaner separation of resonances from background effects than the usual techniques. We observe production of the A1 and A2 mesons as well as the N*(1470) and N*(1700) isobars in the π+π−p system for both reactions. There is strong formation of the doubly resonant states ρ0Δ++ and f0Δ++ and the general features of the nondiffractive events are all in good agreement with one-pion exchange. Detailed comparisons between the data and the OPEM in each LPS plot region show that Van Hove analysis provides a sensitive test for the OPE model.

6 data tables

DEDUCED FROM PRONG CROSS SECTIONS NORMALIZED USING THE DATA OF K. J. FOLEY ET AL., PRL 19, 330 (1967).

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Production of the Delta (1950) by One Pion Exchange in pi+ p Interactions at 13-GeV/c

Gaidos, J.A. ; Miller, David Harry ;
Phys.Rev.D 12 (1975) 2565, 1975.
Inspire Record 2181 DOI 10.17182/hepdata.24834

We have observed the production of high-mass I=32 baryon resonances in π+p interactions at 13 GeV/c. The most prominent of these is found to be the F37 Δ(1950). It is produced by one-pion exchange and the data are well described by on-shell π+p phase shifts. Decays into pπ+ and pπ+π0 are observed and the Δ(1950) is found to have a mass 1.880 ± 0.010 GeV and width of 0.180 ± 0.030 GeV with a production cross section of 43 ± 4 μb.

1 data table

RESONANCE BACKGROUNDS SUBTRACTED.