Radiative Decays of the Upsilon(1S) to gamma pi^0 pi^0, and gamma eta eta and gamma pi^0 eta

TL;DR

This study investigates radiative decays of the Upsilon(1S) into specific meson pairs, measuring some branching ratios and setting upper limits on others, providing insights into meson production in bottomonium decays.

Contribution

First measurement of Upsilon(1S) radiative decays into gamma pi^0 pi^0, gamma eta eta, and gamma pi^0 eta, including branching ratios and upper limits on certain resonances.

Findings

Measured branching ratio for Upsilon(1S) to gamma f_2(1270)

Set upper limits on f_0(1500) and f_0(1710) production

Established upper limit for Upsilon(1S) to gamma pi^0 eta

Abstract

We report on a study of exclusive radiative decays of the Upsilon(1S) resonance into the final states gamma pi^0 pi^0, gamma eta eta and gamma pi^0 eta, using 1.13 inverse femto-barn of e^+ e^- annihilation data collected at sqrt(s)= 9.46 GeV with the CLEO III detector operating at the Cornell Electron Storage Ring. In the channel gamma pi^0 pi^0, we measure the branching ratio for the decay mode Upsilon(1S) to gamma f_2(1270) to be (10.5 \pm 1.6 (+ 1.9)(-1.8)) x 10^-5. We place upper limits on the product branching ratios for the isoscalar resonances f_0(1500) and f_0(1710) for the pi^0 pi^0 and eta-eta decay channels. We also set an upper limit on the Upsilon(1S) radiative decay into pi^0 eta.