Semileptonic decays of heavy mesons

The semileptonic and leptonic decays of heavy mesons are studied as a phenomenological application and exploration of a heavy-quark limit of Dyson-Schwinger equations. The single form factor, ξ(w), which characterises the semileptonic decay in this limit, is calculated and compares well with recent experimental extractions. We obtain a lower bound of 1/3 on the slope-parameter ρ2≡−ξ′(1), which, in calculations with realistic input, is exceeded by a great deal: agreement with experimental data requiring ρ2∼1.2–1.6. The flavour and momentum dependence of the light-quark propagators has observable consequences.