A theoretical explanation of the observed splittings among the P states of charmonium is given with the use of a nonsingular potential model for heavy quarkonia. We also show that the recently observed mass difference between the center of gravity of the 3 P J states and the 1 P 1 state of cc does not provide a direct test of the color hyperfine interaction in heavy quarkonia. Our theoretical value for the mass of the 1 P 1 state is in agreement with the experimental result, and its E1 transition width is 341.8 keV. The mass of the η ′ c state is predicted to be 3622.3 MeV.
Muonium and positronium potentials with radiative corrections are derived from the scattering operator, and general results for the spectra of these systems to order a 3~, are obtained. We also compare our results with those obtained earlier with the Bethe-Salpeter approach, and find a discrepancy in the case of the 1S state. Our theoretical results are in good agreement with the available experimental data.
-(3) of this reference should be s.
We present formulas, based on the helicity formalism, for the angular distributions of the radiative decay products involving q:, $, X,, and ' P I cT states formed in pp collisions. Normalized joint angular observables are expressed in terms of allowed multipole transitions and the ratio of pp production helicity amplitudes.
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