Study of radiative bottomonium transitions using converted photons

Abstract

We use ($111\ifmmode\pm\else\textpm\fi{}1$) million $\ensuremath{\Upsilon}(3S)$ and ($89\ifmmode\pm\else\textpm\fi{}1$) million $\ensuremath{\Upsilon}(2S)$ events recorded by the BABAR detector at the PEP-II B-factory at SLAC to perform a study of radiative transitions between bottomonium states using photons that have been converted to ${e}^{+}{e}^{\ensuremath{-}}$ pairs by the detector material. We observe $\ensuremath{\Upsilon}(3S)\ensuremath{\rightarrow}\ensuremath{\gamma}{\ensuremath{\chi}}_{b0,2}(1P)$ decay, make precise measurements of the branching fractions for ${\ensuremath{\chi}}_{b1,2}(1P,2P)\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\Upsilon}(1S)$ and ${\ensuremath{\chi}}_{b1,2}(2P)\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\Upsilon}(2S)$ decays, and search for radiative decay to the ${\ensuremath{\eta}}_{b}(1S)$ and ${\ensuremath{\eta}}_{b}(2S)$ states.