  This is a conference mostly devoted to diquarks. Although an exotic meson can
in principle be composed of a diquark and an antidiquark, such an exotic is
unlikely to be experimentally observable in the near future. The reason,
according to the model, is that diquark-antidiquark exotics have masses well
above the threshold for decay into two mesons, and are likely to have widths
too large to make them observable. A possible exception is a $ u d \bar b \bar
b$ exotic, but it will be a long time before such a state can be observed even
if it is stable against strong decay.
