Heavy quark expansion for the inclusive decay

Heavy Quark Expansion and Inclusive Decays

Some of the recent developments in the theory and applications of the heavy quark expansion for inclusive processes are reviewed. The topics concern semileptonic and nonleptonic decays, lifetimes and the semileptonic branching fraction.

Heavy Quark Expansion for the Inclusive Decay B̄ → τ ν̄ X

We calculate the differential decay rate for inclusive B̄ → τ ν̄ X transitions to order 1/m2b in the heavy quark expansion, for both polarized and unpolarized tau leptons. We show that using a systematic 1/mb expansion significantly reduces the theoretical uncertainties in the calculation. We obtain for the total branching ratio BR(B̄ → τ ν̄ X) = 2.30±0.25%, and for the tau polarization Apol = −0.7...

Heavy Quark Spectroscopy and Decay

Hadron spectra for semileptonic heavy quark decay.

We calculate the leading perturbative and power corrections to the hadronic invariant mass and energy spectra in semileptonic heavy hadron decays. We apply our results to the B system. Moments of the invariant mass spectrum, which vanish in the parton model, probe gluon bremsstrahlung and nonperturbative effects. Combining our results with recent data on B meson branching ratios, we obtain a lo...

Operator Product Expansion for Inclusive Semileptonic Decays in Heavy Quark Effective Field Theory

Inclusive semileptonic decays are discussed in the framework of heavy quark effective field theory by employing the short distance expansion in the effective theory. The lowest order term turns out to be the parton model; the higher order terms may be regarded as correction terms to the parton model result. The first nonvanishing corrections to the parton model result are given and the lepton e...