Measurement of the mass splittings between the [Formula Presented] states

We present new measurements of photon energies and branching fractions for the radiative transitions [Formula Presented] The masses of the [Formula Presented] states are determined from the measured radiative photon energies. The ratio of mass splittings between the [Formula Presented] substates, [Formula Presented] with [Formula Presented] the [Formula Presented] mass, provides information on the nature of the [Formula Presented] confining potential. We find [Formula Presented] This value is somewhat lower than the previous world average, but more consistent with the theoretical expectation that [Formula Presented] i.e., that this mass splitting ratio is smaller for the [Formula Presented] states than for the [Formula Presented] states.