Recent BaBar Studies of Bottomonium States

Abstract

We present studies in bottomonium spectroscopy carried out with samples of $(98\pm1)$ million $Υ(2S)$ and $(121\pm1)$ million $Υ(3S)$ events recorded with the BaBar detector at the PEP-II asymmetric-energy $e^+ e^-$ collider at SLAC. Precise measurements of the branching fractions for $χ_{b1,2}(1P, 2P)\rightarrow γΥ(1S)$ and $χ_{b1,2}(2P)\rightarrow γΥ(2S)$ transitions, and searches for radiative decay to the $η_b(1S)$ and $η_b(2S)$ states are performed using photons that have converted into an $e^+ e^-$ pair. In addition, we summarize the results of a search for the spin-singlet partner of the $χ_{bJ}(1P)$ triplet, the $h_b(1P)$ state of bottomonium, in the transitions $Υ(3S)\rightarrow π^0 h_b$ and $Υ(3S)\rightarrow π^+π^- h_b$.