Measurement of Upper Limits for Upsilon --> gamma + R Decays
Motivated by concerns regarding possible two-body contributions to the recently-measured inclusive Upsilon(nS)->gamma+X (n=1, 2, 3) direct photon spectra, we report on a new study of exclusive radiative decays of these narrow Upsilon(nS) resonances into two-body final states R+gamma, with R a narrow resonant hadronic state decaying into four or more charged particles. Such two-body processes are not explicitly addressed in the extant theoretical frameworks used to calculate the inclusive direct photon spectra, and must also be explicitly inserted into Monte Carlo simulations. Using data collected from the CLEO III detector at the Cornell Electron Storage Ring, we present upper limits of order 0.01 per cent for such bottomonium two-body decays as a function of the R recoil mass.