Conventional estimates are reviewed for charmed particle lifetimes. Free‐quark models give values of (a few) ×10−13 sec to (a few) ×10−12 sec. The shorter of these values also follows from an extrapolation based on D→ Keν. Possible differences among the lifetimes and production rates of D0, D+, F+, C0+, the heavy lepton τ, and the fifth quark b are discussed. Extreme values of mixing angles in a six‐quark model could extend charmed particle lifetimes by a factor of at most three from the above estimates, while shorter lifetimes than those predicted could occur for some species like D0 or F+ if their nonleptonic decays were enchanced. The predictions are discussed in the light of some current experimental results, and it is estimated that σ (pp→charm) ?10μb at 400 GeV/c.

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