Multihadron semileptonic decays of charmed mesons

We discuss and illustrate the effects of hadron multiplicity in the semileptonic decay of charmed mesons. Using specific models for the decay matrix elements, and for the production process where necessary, we evaluate the consequences of multiple-hadron decay products on distributions of practical interest: (i) energy distributions in e⁺e^- colliding beam measurements, (ii) energy distributions in leptoproduction, (iii) transverse-momentum distributions in leptoproduction, photoproduction, and hadroproduction, and (iv) Kl invariant-mass distributions and other two-particle correlations. Theoretical estimates suggest that D→Klν and D→K*lν modes, in similar proportion, approximately saturate the inclusive semileptonic rate; this is consistent with existing data. Effects of hadronic form factors on decay rates and distributions are considered. Calculated acceptance corrections for undetected slow secondary muon in neutrino dimuon experiments increase the rates to 2-3% of charged-current events.