Further Experimental Studies of Two-Body Radiative \Upsilon Decays

TL;DR

This study searches for specific radiative decays of the Upsilon(1S) meson into eta and f_{J}(2220), setting upper limits on their branching fractions based on experimental data, and compares results with other measurements and theories.

Contribution

First experimental limits on Upsilon radiative decays to eta and f_{J}(2220) using CLEO II data, enhancing understanding of bottomonium decay processes.

Findings

No candidate events for Upsilon to gamma eta decays, setting a limit of < 2.1 x 10^{-5}.

Limits of approximately 1.5 x 10^{-5} on Upsilon to gamma f_{J}(2220) decays.

Results are consistent with other radiative decay measurements and theoretical models.

Abstract

Continuing our studies of radiative Upsilon(1S) decays, we report on a search for Upsilon to gamma eta and Upsilon to gamma f_{J}(2220) in 61.3 pb^{-1} of e^{+}e^{-} data taken with the CLEO II detector at the Cornell Electron Storage Ring. For the gamma eta search the three decays of the eta meson to pi^{+}pi^{-}pi^{0}, pi^{0}pi^{0}pi^{0}, and gamma gamma were investigated. We found no candidate events in the two (3\pi)^{0} modes and no significant excess over expected backgrounds in the gamma gamma mode to set a limit on the branching fraction of B(Upsilon to gamma eta) < 2.1 x 10^{-5} at 90% C.L. The three charged two-body final states h h-bar (h = pi^{+}, K^{+}, p) were investigated for f_{J}(2220) production, with one, one, and two events found, respectively. Limits at 90% C.L. of B(\Upsilon to gamma f_{J}) x B(f_{J} to h h-bar) ~ 1.5 x 10^{-5} have been set for each of these modes. We compare our results to measurements of other radiative Upsilon decays, to measurements of radiative J/psi decays, and to theoretical predictions.