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

Abstract

Using CLEO data, we study the production of the antideuteron, d̄, in Υ(nS) resonance decays and the nearby continuum. The branching ratios obtained are Bdir(Υ(1S)→d̄X)=(3.36±0.23±0.25) ×10-5, B(Υ(1S)→d̄X)=(2.86±0.19±0.21) ×10-5, and B(Υ(2S)→d̄X)=(3.37±0.50±0.25) ×10-5, where the "dir" superscript indicates that decays produced via reannihilation of the bb̄ 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)→d̄X)<1.3×10-5, and continuum production σ(e+e-→d̄X)<0.031pb. The Υ(2S) data is also used to extract a limit on χbJ→d̄X. The results indicate enhanced deuteron production in ggg, ggγ hadronization compared to γ*→qq̄. Baryon number compensation is also investigated with the large Υ(1S)→d̄X sample. © 2007 The American Physical Society.