  Bottomonium S-wave states were studied using lattice NRQCD. Masses of ground
and excited states were calculated using multiexponential fitting to a set of
correlation functions constructed using both local and wavefunction-smeared
operators. Three-point functions for M1 transitions between vector and
pseudoscalar states were computed. Robust signals for transitions involving the
first two excited states were obtained. The qualitative features of the
transition matrix elements are in agreement with expectations. The calculated
values of matrix elements for Y(2S) and Y(3S) decay are considerably larger
than values inferred from measured decay widths.
