First Measurement of the Form Factors in the Decays D0→ρ−e+νe and D+→ρ0e+νe

Le résumé fourni par la source

The beauty to up quark coupling constant $|{V}_{ub}|$ can be extracted from $B\ensuremath{\rightarrow}\ensuremath{\rho}{e}^{+}{\ensuremath{\nu}}_{e}$ combined with the form factors for $D\ensuremath{\rightarrow}{K}^{*}{e}^{+}{\ensuremath{\nu}}_{e}$ and $B\ensuremath{\rightarrow}V{\ensuremath{\ell}}^{+}{\ensuremath{\ell}}^{\ensuremath{-}}$ and $D\ensuremath{\rightarrow}\ensuremath{\rho}{e}^{+}{\ensuremath{\nu}}_{e}$. Using the entire CLEO-c $\ensuremath{\psi}(3770)\ensuremath{\rightarrow}D\overline{D}$ event sample, corresponding to an integrated luminosity of $818\text{ }\text{ }{\mathrm{pb}}^{\ensuremath{-}1}$ and approximately $5.4\ifmmode\times\else\texttimes\fi{}{10}^{6}$ $D\overline{D}$ events, we measure the form factors for the decays ${D}^{0}\ensuremath{\rightarrow}{\ensuremath{\rho}}^{\ensuremath{-}}{e}^{+}{\ensuremath{\nu}}_{e}$ and ${D}^{+}\ensuremath{\rightarrow}{\ensuremath{\rho}}^{0}{e}^{+}{\ensuremath{\nu}}_{e}$ for the first time and the branching fractions with improved precision. A four-dimensional unbinned maximum likelihood fit determines the form factor ratios to be $V(0)/{A}_{1}(0)=1.48\ifmmode\pm\else\textpm\fi{}0.15\ifmmode\pm\else\textpm\fi{}0.05$ and ${A}_{2}(0)/{A}_{1}(0)=0.83\ifmmode\pm\else\textpm\fi{}0.11\ifmmode\pm\else\textpm\fi{}0.04$. Assuming Cabibbo-Kobayashi-Maskawa unitarity, the known $D$ meson lifetimes, and our measured branching fractions we obtain the form factor normalizations ${A}_{1}(0)$, ${A}_{2}(0)$, and $V(0)$. We also present a measurement of the branching fraction for ${D}^{+}\ensuremath{\rightarrow}\ensuremath{\omega}{e}^{+}{\ensuremath{\nu}}_{e}$ with improved precision.

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