Confinement, crossing symmetry, and glueballs

It is suggested that the quark-confining force is related by crossing symmetry to a color-singlet glueball g which is well described as a loop of one quantum of color magnetic flux. Electron pair annihilation as high as ≈ 2 GeV above the Y mass could produce Y → ℓ+ℓ− accompanied by g or one of its excited states.