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Angular distributions in radiative decays of charmonium [chi][sub 1] and [chi][sub 2] states formed in p[anti p] annihilations

Thesis/Dissertation ·
OSTI ID:7015346
A study of the angular distributions in the reactions p[anti p] [yields][chi][sub 1/2] [yields] J/[psi][gamma] [yields] e[sup +]e[sup [minus]] [gamma] is presented, using a sample of 2309 [chi][sub 2] events and 360 [chi][sub 1] events. The data were collected by Fermilab experiment E-760, which is the first high-statistics experiment studying charmonium states formed directly in p[anti p] annihilations. From the analysis of the angular distributions it is found that the helicity in the formation process p[anti p] [yields] [chi][sub 2] is mainly [+-]1, and that the radiative decays [chi][sub 1,2] [yields] J/[psi][gamma] are predominantly dipole transitions. The contribution of helicity zero in the [chi][sub 2] formation process is found to be B[sup 2][sub 0] = 0.01 [+-][sup 0.11][sub 0.12]. The normalized quadrupole amplitudes in the radiative decays are a[sub 2]([chi][sub 2]) = [minus]0.161[+-][sup 0.056][sub 0.061] and a[sub 2]([chi][sub 1]) = [minus]0.129 [+-] 0.059, and the octupole amplitude in the [chi][sub 2] decay is a[sub 3]([chi][sub 2]) = [minus]0.017[+-][sup 0.042][sub 0.040]. The results, which represent a significant improvement on the experimental knowledge of the angular distribution parameters, are compared with the measurements from previous experiments, and with theoretical predictions.
Research Organization:
Pennsylvania State Univ., University Park, PA (United States)
OSTI ID:
7015346
Country of Publication:
United States
Language:
English