The Light-Front Model for Exclusive Semileptonic B- and D-decays

Abstract

An explicit relativistic light-front quark model is presented which gives the momentum transfer dependent form factors of weak hadronic currents among heavy pseudoscalar and vector mesons in the whole accessible kinematic region $0\le q^2\le q_{max}^2$. For the numerical investigations of the $B\to D^{\ast }l{\nu }_l$, $B\to \rho l{\nu }_l$, $D\to K^{\ast }l{\nu }_l$ and $D\to \rho l{\nu }_l$ semileptonic decays the equal time wave functions corresponding to the updated version of the ISGW model are adopted. Using the available experimental information on branching fractions $BR(B\to D^{\ast }l{\nu }_l)$ and $BR(B\to \rho l{\nu }_l)$ the CKM parameters $V_{cb}$ and $V_{ub}$ were estimated: $|V_{cb}|=0.036\pm 0.004$, $|V_{ub}|=0.0033\pm 0.0004$. The model is further tested by comparison with experimental data, QCD sum rules and lattice calculations.

Comments: 27 pages, Latex, with 9 postscript figures; some different references and numbers in table 5. Thanks to P. Ball for comments