2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/206163We present a preliminary measurement of the q2 dependence of the D0 --> K- e+ nu_e decay rate. This rate is proportional to the hadronic form factor squared, specified by a single parameter. This is either the mass in the simple pole ansatz m_pole = (1.854 +- 0.016 +- 0.020) GeV/c2 or the scale in the modified pole ansatz alpha_pole = 0.43 +- 0.03 +- 0.04. The first error refers to the statistical, the second to the systematic uncertainty.23 pages, 7 postscript figues, submitted to ICHEP2006High Energy Physics - Experimenttext