Confinement, Crossing Symmetry, and Glueballs

We suggest that the quark-confining force is related by crossing symmetry to a color-singlet glueball $\mathcal{G}$ which is well described as a loop of one quantum of color magnetic flux. Electron pair annihilation as high as $\approx 2 GeV$abovethe$\Upsilon$masscouldproduce$\Upsilon \rightarrow \ell^+\ell^-$accompaniedby${\cal G}$ or one of its excited states.