New Measurements of Upsilon(1S) Decays to Charmonium Final States

TL;DR

This paper presents new measurements of Upsilon(1S) decays into charmonium states using larger data samples, including first observations of certain decay modes, and compares the results with theoretical models.

Contribution

It provides the first measurements of Upsilon(1S) decays to chi_cJ states and offers detailed spectra analysis, enhancing understanding of bottomonium decay mechanisms.

Findings

First observations of Upsilon(1S) decays to chi_c1 and chi_c2.

Measured branching fractions for various decay channels.

Comparison of spectra with color octet and singlet model predictions.

Abstract

Using substantially larger data samples collected by the CLEO III detector, we report on new measurements of the decays of Upsilon(1S) to charmonium final states, including J/Psi, psi(2S), and chi_cJ. The latter two are first observations of these decays. We measure the branching fractions as follows: B(Y(1S)--> J/Psi+X)=(6.4+-0.4+-0.6)x10^-4, B(Y(1S)--> psi(2S)+X)/B(Y(1S)--> J/Psi+X)=0.41+-0.11+-0.08, B(Y(1S)--> chi_c1+X)/B(Y(1S)--> J/Psi+X)=0.35+-0.08+-0.06, B(Y(1S)--> chi_c2+X)/B(Y(1S)--> J/Psi+X)=0.52+-0.12+-0.09, and B(Y(1S)--> chi_c0+X)/B(Y(1S)--> J/Psi+X)<7.4% at 90% confidence level. We also report on the momentum and angular spectra of J/Psi's in Upsilon(1S) decay. The results are compared to predictions of the color octet and color singlet models.