How Often Do Diquarks Form? A Very Simple Model
  Starting from a textbook result, the nearest-neighbor distribution of particles in an ideal gas, we develop estimates for the probability with which quarks $q$ in a mixed $q$, $\bar q$ gas are more strongly attracted to the nearest $q$, potentially forming a diquark, than to the nearest $\bar q$. Generic probabilities lie in the range of tens of percent, with values in the several percent range even under extreme assumptions favoring $q\bar q$ over $qq$ attraction. 
Richard F. Lebed
hep-ph