Angular distributions of heavy-quark jets ine+e−annihilation

We propose that the angular distribution of heavy-quark jet production in $e^{+}{e}^{-}$ annihilation is a clean place to measure the quark mass (e.g., accurate to within a few percent for the $b$ quark) in perturbative quantum chromodynamics (QCD). We present our argument as to why this is the case (as compared to measurements given by the total cross section). We also evaluate the leading-order perturbative QCD correction to the angular distribution; we find that the QCD effect on the angular distribution is small except when the velocity $v$ is close to one. Our formula gives the leading QCD correction to the angular distribution of hadronic jets, with the quark-mass effects fully taken into account.