Couplings of heavy mesons with soft pions in QCD
نویسنده
چکیده
< π(q) D(q2)|D(q1, ǫ) >= gD∗Dπ(ǫ · q) (1) governs the decay D → Dπ; from the experimental branching ratio BR(D → Dπ) = 68.1 ± 1.0 ± 1.3 % [1] and from the measurement Γ(D) < 131 KeV [2] the upper limit gD∗Dπ ≤ 20.6 can be derived. The analogous coupling constant in theB channel, gB∗Bπ, describes the contribution of the B ∗ pole to the form factor F 1 (q ) of the semileptonic decay B → πlν:
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