  Production of even-parity charmed mesons in hadronic B decays is studied.
Specifically, we focus on the Cabibbo-allowed decays $\bar B\to D^{**}\pi$ and
$\bar D^{**}_sD^{(*)}$, where $D^{**}$ denotes generically a p-wave charmed
meson. While the measured color-allowed decays $\bar B^0\to D^{**+}\pi^-$ are
consistent with the theoretical expectation, the experimental observation of
$B^-\to D^{**0}\pi^-$ for the broad $D^{**}$ states is astonishing as it
requires that the color-suppressed contribution dominates over the
color-allowed one, even though the former is $1/m_b$ suppressed in the heavy
quark limit. In order to accommodate the data of $\bar B\to D^{**}\pi^-$, it is
found that $a_2/a_1\approx -0.5$ with a sign opposite to that in $\bar B\to
D\pi$ decays, where $a_1$ and $a_2$ are the effective Wilson coefficients for
color-allowed and color-suppressed decay amplitudes, respectively. The decay
constants and form factors for $D^{**}$ and the Isgur-Wise functions
$\tau_{1/2}(\omega)$ and $\tau_{3/2}(\omega)$ are extracted from the data of
$B\to D^{**}\pi$ decays. The Isgur-Wise functions calculated in the covariant
light-front quark model are in good agreement with experiment. The neutral
modes $\bar B^0\to D^{**0}\pi^0$ for $D^{**}=D^*_0(2400),D'_1(2430)$ and $\bar
B^0\to D'^0_1(2430)\omega$ are predicted to have branching ratios of order
$10^{-4}$ which are also supported by isospin argument. The decay constants of
$D_{s0}^*(2317)$ and $D'_{s1}(2460)$ are inferred from the measurements of
$\bar B\to D_s^{**-}D$ to be $58\sim 86$ MeV and $130\sim 200$ MeV,
respectively. Contrary to the decay constants $f_{D_0^*}$ and $f_{D'_1}$ which
are similar in size, the large disparity between $f_{D_{s0}^*}$ and
$f_{D'_{s1}}$ is surprising and unexpected.

High Energy Physics - Phenomenology;High Energy Physics - Experiment