Semileptonic decay of charmed particles and weak form factors

We present a phenomenological analysis of semileptonic decays of charmed particles based on SU(4) symmetry and (axial-) vector-meson dominance of weak form factors. The modified monopole form factors, which have been recently discussed by Sehgal, are extensively applied for charmed-particle decays throughout this work. These form factors contain an as yet undetermined parameter. We find a precise quantitative relation, depending on this parameter, between semileptonic decay rates and production cross sections of charmed baryons in neutrino-induced quasielastic scattering. The preliminary data on the latter processes suggest that either (i) form factors decrease in the spacelike region much faster than previously expected, or (ii) the Cabibbo factor is considerably smaller than the conventional value assumed for production processes of charmed baryons, i.e., ${sin}^2\theta \ll 0.05$. We also discuss a few methods to test the basic hypotheses underlying this work.