Hyperfine splitting and the experimental candidates for \eta_b(2S)

Abstract

Predictions for the hyperfine splitting of 2S bottomonia are compared with the two recent experimental candidates for the \eta_b(2S). The smaller splitting of the Belle state is consistent with unquenched lattice QCD computations, many potential models, and a model-independent relation which works well for charmonia. The larger splitting for the state extracted from CLEO data is inconsistent with most predictions.

Comments: 8 pages, 1 figure. Journal version with an additional reference added