1ST OBSERVATION ON THE PRODUCTION OF PI(0) IN THE REACTION D+D-]ALPHA+PI(0) VIOLATING CONSERVATION OF CHARGE SYMMETRY AND MEASUREMENT OF THE REACTION D+D-]ALPHA+GAMMA

The reaction d + d --> alpha + pi-0 which is in clear violation of charge symmetry conservation, has been observed for the first time at a laboratory energy of 1.10 GeV in an experiment carried out at the Saturne synchrotron at Saclay. The number of pi-0's detected corresponds to a differential cross section d-sigma/d-OMEGA*(pi-0) = 0.97 +/- 0.20 +/- 0.15 pb/sr at a centre-of-mass angle of theta-c.m. = 107-degrees, where the first error bar refers to the statistical uncertainty and the second to the systematic. The reaction d + d --> alpha + gamma was measured simultaneously with the pi-0 production, leading to a differential cross section of d-sigma/d-OMEGA*(gamma) = 0.82 +/- 0.18 +/- 0.10 pb/sr at the slightly larger angle of theta-c.m. = 110-degrees. The available predictions of theoretical models of charge symmetry breaking, based upon eta/pi mixing, fall an order of magnitude below our measurement. However, these predictions for the eta/pi mixing level might be boosted by the eta threshold (1.121 GeV) proximity, where this experiment is performed.