Dipion production in a 4 GeV/c pi[plus] d experiment

Woodworth, Philip Leslie (1974). Dipion production in a 4 GeV/c pi[plus] d experiment. University of Birmingham. Ph.D.

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Abstract

A bubble chamber experiment is described using data from the C.E.R.N. 2m bubble chamber filled with deuterium and exposed to a 4 GeV/c \(π^+\) beam. Measurements are presented of the U.5. \(π^+\) beam momentum, and the level of contamination in the beam is estimated. A brief review is given of the computer programs used in the processing of 2m bubble chamber film for physics analysis.
The channel
\(π^+d \rightarrow p_s p π^+ π^- ( \sigma = 2.10^±0.17m b) \) (1)
is investigated and cross sections are obtained for the quasi-two-body reactions
\(π^+d \rightarrow p_s p \rho^0 ( \sigma = 1.21^±0.16m b) \) (2)
and \(π^+d \rightarrow p_a p f^0 ( \sigma = 0.53^±0.06m b) \) (3)
An Estabrooks and Martin amplitude analysis is made of reaction (2) using 5279 events from the mass interval
\(0.68<M_{ππ} < 0.88 GeV/c^2 \)
Results are presented on the spin structure and production mechanism of the \(\rho^0\) meson. A comparison is made of the results of this analysis with those of a higher energy \(π^-p\) experiment and the predictions of an π exchange absorption model.
The isospin zero S wave ππ scattering phase shifts are obtained for ππ effective mass less than 1 4 GeV/c². Evidence is presented favouring a set of phase shifts rising slowly through the rho region to be 90° at about 900 MeV/c² in ππ effective mass.
An investigation is also made of the branching ratios of the \(f^0\) meson into final states other than \(π^+π^-\). These include
\(π^+d \rightarrow p_s p K^+ K^-\) (4)
\(π^+d \rightarrow p_s p 2π^+ 2π^-\) (5)
\(π^+d \rightarrow p_s p 2π^+ 2π^- π^0\) (6)
\(π^+d \rightarrow p_s p π^+ π^- M M\) (7)
\(π^+d \rightarrow p_s p 2π^+ 2π^- M M\) (8)
where M M indicates missing particles. Evidence is presented for f° decay into channels (4) and (5) and the decay rates are measured.