Antideuteron production in Υ(nS) decays and the nearby continuum

<p>Using CLEO data, we study the production of the antideuteron, d̅ , in Υ(nS) resonance decays and the nearby continuum. The branching ratios obtained are B^dir(Υ(1S)→d̅ X)=(3.36±0.23±0.25)×10^-5, B(Υ(1S)→d̅ X)=(2.86±0.19±0.21)×10^-5, and B(Υ(2S)→d̅ X)=(3.37±0.50±0.25)×10^-5, where the “dir” superscript indicates that decays produced via reannihilation of the bb̅ pair to a γ^* are removed from both the signal and the normalizing number of Υ(1S) decays in order to isolate direct decays of the Υ(1S) to ggg, ggγ. Upper limits at 90% C.L. are given for B(Υ(4S)→d̅ X)<1.3×10^-5, and continuum production σ(e⁺e^-→d̅ X)<0.031  pb. The Υ(2S) data is also used to extract a limit on χ_bJ→d̅ X. The results indicate enhanced deuteron production in ggg, ggγ hadronization compared to γ^*→qq̅ . Baryon number compensation is also investigated with the large Υ(1S)→d̅ X sample.</p>