Exclusive heavy-meson production and the Z width

We calculate in lowest order QCD perturbation theory the production from Z⁰ decay and e⁺e^? annihilation of two mesons, each containing a heavy quark. With reasonable assumptions about the vertex functions that couple mesons to quarks, we find that the rates for these final states are strongly enhanced. Present-day knowledge even allows these rates to be so large that the Z⁰ may be too wide to be detected in $\text{p}\text{p}$ collisions, with disastrous consequences also for event rates at e⁺e^? colliders.