A Study of the Reactions π^±p → π^±π^+π^-π^op and π^±p → π^±π^+π^+π^-nat P_(lab) = 14 GeV/c Using a Triggered Hybrid Bubble Chamber

Physics

Nagy, Frank Joseph ; Peck, Charles W.

University:California Institute of Technology

Department:Physics, Mathematics and Astronomy

关键词: Physics;   

Others  :  https://thesis.library.caltech.edu/10186/1/Nagy_fj_1980.pdf

美国|英语

来源: Caltech THESIS

【 摘 要 】

We have studied the reactions π^±p → π^±π⁺π^-π^op and π^±π⁺π⁺π^-nat a beam momentum of 14 GeV/c. A bubble chamber with a downstreamwire spark chamber spectrometer was used to record the data. The bubblechamber camera was triggered by identifing inelastic events in anonline computer using data from the downstream spectrometer. The filmtaken represents an exposure of about 80 events/microbarn for the π⁺data and 70 events/microbarn for the π^- data.

We find these reactions to be very rich in subprocesses involvingbaryon and meson resonances. The invariant mass spectra are presentedand estimates of the cross sections for the production of known baryonand meson resonances are given.

The reactions π^±p → π^±ω^op provided more evidence for the existenceof an N^* resonance with mass 1789±5 MeV and width 81±9 MeV which decaysinto ω^op. Using previously published data along with our results, wefind that the production cross section of this N^* is independent of s.Studies of the angular distributions raise questions about the validityof the spin-parity analyses of this N^* done so far.

We have studied the processes π^±p → π^±η^op in the relatively unexploredregion of low |t_ππ| and small η^op mass.We found that the π⁺η^opcross section is about twice the π^-η^op cross section in this region.The η^op mass spectrum for the π⁺ data shows an enhancement at about1600 MeV while the π^- data show no evidence of a peak in the η^op massspectrum.