D-wave quarkonium levels of theΥfamily

Abstract

A key test of the nonrelativistic potential description of quarkonium is the confirmation of predicted D-wave levels. For the bb¯ system (Υ family), the lowest spin-triplet levels (1 ${}_{}{}^3{}_{}{}^{}D$) are expected to lie in the range 10 157±10 MeV/$c^2$ and the next set of levels is expected in the range 10 441±10 MeV/$c^2$. Predictions are made for electric dipole transitions involving these levels, and specific suggestions are made for their observation. The most favorable decay chain appears to be Υ(3S)→${\gamma }_1$+2P→${\gamma }_1$+${\gamma }_2$+1D→${\gamma }_1$+${\gamma }_2$+${\gamma }_3$+1P, where ${\gamma }_1$ and ${\gamma }_2$ have energies of about 100 MeV and &≊250 MeV. Angular distributions of these photons are discussed.