Recent BaBar Studies of Bottomonium States

Abstract

We present studies in bottomonium spectroscopy carried out with samples of $(98\pm 1)$ million ${\rm Y}(2S)$ and $(121\pm 1)$ million ${\rm Y}(3S)$ events recorded with the BaBar detector at the PEP-II asymmetric-energy $e^{+}{e}^{-}$ collider at SLAC. Precise measurements of the branching fractions for ${\chi }_{b1,2}(1P,2P)\to \gamma {\rm Y}(1S)$ and ${\chi }_{b1,2}(2P)\to \gamma {\rm Y}(2S)$ transitions, and searches for radiative decay to the ${\eta }_b(1S)$ and ${\eta }_b(2S)$ 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 ${\chi }_{bJ}(1P)$ triplet, the $h_b(1P)$ state of bottomonium, in the transitions ${\rm Y}(3S)\to {\pi }^0{h}_b$ and ${\rm Y}(3S)\to {\pi }^{+}{\pi }^{-}{h}_b$.