Observation of $P$-Wave $b\overline{b}$ Bound States

The existence of $P$-wave $b\overline{b}$ bound states ${{\chi }_b}^{\prime }$ is demonstrated by observation of photons from the transition ${\Upsilon }^{\prime \prime }\to \gamma +{{\chi }_b}^{\prime }$ in the inclusive photon spectrum from ${\Upsilon }^{\prime \prime }$ decays. The center of gravity of the observed photon energies is 98 MeV and the branching ratio for the transition of the ${\Upsilon }^{\prime \prime }$ to the ${{\chi }_b}^{\prime }$ states is (34±3)% (statistical).