Recent BaBar Studies of Bottomonium States

TL;DR

This paper reports precise measurements of bottomonium state transitions, searches for new states, and summarizes findings from BaBar's extensive data on bottomonium spectroscopy.

Contribution

It provides new precise branching fraction measurements and searches for elusive bottomonium states using photon conversions and large data samples.

Findings

Measured branching fractions for specific bottomonium transitions.

Searched for and set limits on radiative decays to eta_b states.

Investigated the existence of the h_b(1P) state in bottomonium.

Abstract

We present studies in bottomonium spectroscopy carried out with samples of $(98\pm1)$ million $\Upsilon(2S)$ and $(121\pm1)$ million $\Upsilon(3S)$ events recorded with the BaBar detector at the PEP-II asymmetric-energy $e^+ e^-$ collider at SLAC. Precise measurements of the branching fractions for $\chi_{b1,2}(1P, 2P)\rightarrow \gamma \Upsilon(1S)$ and $\chi_{b1,2}(2P)\rightarrow \gamma \Upsilon(2S)$ 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 $\Upsilon(3S)\rightarrow \pi^0 h_b$ and $\Upsilon(3S)\rightarrow \pi^+\pi^- h_b$.