Reaction π-p→ π0π0n has been measured with high statistics in the beam momentum range 270-750 MeV/c. The data were obtained using the Crystal Ball multiphoton spectrometer, which has 93% of 4π solid angle coverage. The dynamics of the π-p→ π0π0n reaction and the dependence on the beam energy are displayed in total cross sections, Dalitz plots, invariant-mass spectra, and production angular distributions. Special attention is paid to the evaluation of the acceptance that is needed for the precision determination of the total cross section σt(π-p→ π0π0n). The energy dependence of σt(π-p→ π0π0n) shows a shoulder at the Roper resonance [i.e., the N(1440)1/2+], and there is also a maximum near the N(1520)3/2-. It illustrates the importance of these two resonances to the π0π0n production process. The Dalitz plots are highly nonuniform; they indicate that the π0π0n final state is dominantly produced via the π0Δ0(1232) intermediate state. The invariant-mass spectra differ much from the phase-space distributions. The production angular distributions are also different from the isotropic distribution, and their structure depends on the beam energy. For beam momenta above 550 MeV/c, the density distribution in the Dalitz plots strongly depends on the angle of the outgoing dipion system (or equivalently on the neutron angle). The role of the f0(600) meson (also known as the σ) in π0π0n production remains controversial.
ASJC Scopus subject areas
- Nuclear and High Energy Physics