Phys. Rev. D 70, 072001 (2004) [18 pages]New measurements of Υ(1S) decays to charmonium final statesReceived 9 July 2004; published 5 October 2004 Using data collected by the CLEO III detector at CESR, we report on measurements of Υ(1S) decays to charmonium final states. The data sample used for this analysis consists of 21.2×106 Υ(1S) decays, representing about 35 times more data than previous CLEO Υ(1S) data samples. We present substantially improved measurements of the branching fraction B(Υ(1S)→J/ψ+X) using J/ψ→μ+μ- and J/ψ→e+e- decays. The branching fractions for these two modes are averaged, thereby obtaining: B(Υ(1S)→J/ψ+X)=(6.4±0.4(stat)±0.6(syst))×10-4. A greatly improved measurement of the J/ψ momentum distribution is presented and indicates a spectrum which is much softer than predicted by the color-octet model and somewhat softer than the color-singlet model. First measurements of the J/ψ polarization and production angle are also presented. In addition, we report on the first observation of Υ(1S)→ψ(2S)+X and evidence for Υ(1S)→χcJ+X. Their branching fractions are measured relative to B(Υ(1S)→J/ψ+X) and are found to be {[B(Υ(1S)→ψ(2S)+X)]/[B(Υ(1S)→J/ψ+ X)]}=0.41±0.11(stat)±0.08(syst), {[B(Υ(1S)→χc1+X)]/[B(Υ(1S)→J/ψ+X)]}=0.35± 0.08(stat)±0.06(syst), {[B(Υ(1S)→χc2+X)]/[B(Υ(1S)→J/ψ+X)]}=0.52±0.12(stat)±0.09(syst), and {[B(Υ(1S)→χc0+X)]/[B(Υ(1S)→J/ψ+X)]}<7.4 at 90% confidence level. The resulting feed-down contributions to J/ψ are [24±6(stat)±5(syst)]% for ψ(2S), [11±3(stat)±2(syst)]% for χc1, [10±2(stat)±2(syst)]% for χc2, and <8.2% at 90% confidence level for χc0. These measurements (apart from χc0) are about a factor of 2 larger than expected based on the color-octet model. © 2004 The American Physical Society URL:
http://link.aps.org/doi/10.1103/PhysRevD.70.072001
DOI:
10.1103/PhysRevD.70.072001
PACS:
13.25.Gv
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