Observation of the Charge Symmetry Breaking d+d→4He+π0 Reaction Near Threshold
Abstract
We report the first observation of the charge symmetry breaking d+d→4He+π0 reaction near threshold. Measurements using a magnetic channel (gated by two photons) of the 4He scattering angle and momentum (from time of flight) permitted reconstruction of the π0 “missing mass,” the quantity used to separate 4He+π0 events from the continuum of double radiative capture 4He+γ+γ events. We measured total cross sections for neutral pion production of 12.7±2.2 pb at 228.5MeV and 15.1±3.1 pb at 231.8MeV. The uncertainty is dominated by statistical errors. These cross sections arise fundamentally from the down-up quark mass difference and quark electromagnetic effects that contribute in part through meson mixing (e.g., π0-η) mechanisms.
- Publication:
-
Physical Review Letters
- Pub Date:
- October 2003
- DOI:
- 10.1103/PhysRevLett.91.142302
- arXiv:
- arXiv:nucl-ex/0305032
- Bibcode:
- 2003PhRvL..91n2302S
- Keywords:
-
- 24.80.+y;
- 24.85.+p;
- 25.10.+s;
- 25.45.-z;
- Nuclear tests of fundamental interactions and symmetries;
- Quarks gluons and QCD in nuclei and nuclear processes;
- Nuclear reactions involving few-nucleon systems;
- <sup>2</sup>H-induced reactions;
- Nuclear Experiment
- E-Print:
- 7 pages, 2 figures, plain TeX