Photon transitions in Upsilon(2S) and Upsilon(3S)

TL;DR

This paper provides precise measurements of photon transition rates in Upsilon(2S) and 3S decays, including the first measurement of a rare transition and limits on hindered M1 transitions, enhancing understanding of bottomonium spectroscopy.

Contribution

It presents the most accurate electric dipole transition rates and energies for Upsilon decays, and reports the first measurement of the Upsilon(3S)->gamma chi_b0(1P) transition.

Findings

Precise E1 transition rates and energies measured.

First measurement of Upsilon(3S)->gamma chi_b0(1P).

Upper limits set on hindered M1 transitions.

Abstract

We have studied the inclusive photon spectra in Upsilon(2S) and \Upsilon(3S) decays using a large statistics data sample obtained with the CLEO III detector. We present the most precise measurements of electric dipole (E1) photon transition rates and photon energies for Upsilon(2S)->gamma chi_bJ(1P) and Upsilon(3S)->gamma chi_bJ(2P) J=0,1,2. We measure the rate for a rare E1 transition Upsilon(3S)->gamma chi_b0(1P) for the first time. We also set upper limits on the rates for the hindered magnetic dipole (M1) transitions to the eta_b(1S) and eta_b(2S) states.