A Study of radiative bottomonium transitions using converted photons

Abstract

We use ( 111 ± 1 ) million Υ ( 3 S ) and ( 89 ± 1 ) million Υ ( 2 S ) 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 − pairs by the detector material. We observe Υ ( 3 S ) → γ χ b 0 , 2 ( 1 P ) decay, make precise measurements of the branching fractions for χ b 1 , 2 ( 1 P , 2 P ) → γ Υ ( 1 S ) and χ b 1 , 2 ( 2 P ) → γ Υ ( 2 S ) decays, and search for radiative decay to the η b ( 1 S ) and η b ( 2 S ) states.