Heavy Quark Expansion for the Inclusive Decay B̄ → τ ν̄ X
نویسندگان
چکیده
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 = −0.706± 0.006. From the experimental measurement of the branching ratio at LEP, we derive the upper bound λ1 ≤ 0.8 GeV for one of the parameters of the heavy quark effective theory. December 1993
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