The sensitivity of observables in radiative decays ψ(2S) → γχc1,2 → γγJ/ψ to quadrupole (M2) admixtures in the dominant electric dipole (E1) transitions is explored. Emphasis is placed on distributions in a single angle, and several examples are given. PACS numbers: 14.40.Gx, 13.20.Gd, 13.40.Hq, 12.39.Jh Radiative decays of charmonium (c¯c) states are expected to be dominated by electric dipole (E1) transitions, with higher multipoles suppressed by powers of photon energy divided by quark mass . (An early discussion of charmonium radiative transitions may be found in Ref. .) The search for contributions of higher multipoles is of interest as a source of information on the charmed quark’s magnetic moment, which is difficult to measure directly because of the extremely short lifetime of charmed hadrons. The possibility of anomalous magnetic moments of heavy quarks being larger than those of light ones, as a result of light-quark loops, was raised in Ref. . Expectations for the magnitude of magnetic quadrupole (M2) transitions in charmonium were calculated in Ref. , and detailed discussions of various ways to extract the M2/E
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