Hadronic B Decays Involving Even Parity Charmed Mesons

Hadronic B decays containing an parity-even charmed meson in the final state are studied. Specifically we focus on the Cabibbo-allowed decays $\bar B\to D^{} \pi(\rho), D^{}\bar D_s^{()}, \bar D^{**}_sD^{()}$and$\bar B_s\to D_s^{}\pi(\rho)$,where$D^{}$ denotes generically a p-wave charmed meson. The $B\to D^{\ast \ast }$ transition form factors are studied in the improved version of the Isgur-Scora-Grinstein-Wise quark model. We apply heavy quark effective theory and chiral symmetry to study the strong decays of p-wave charmed mesons and determine the magnitude of the $D_1^{1\mathrm{/}2}-D_1^{3\mathrm{/}2}$ mixing angle. Except the decay to $D_1(2427{)}^0{\pi }^{-}$ the predictions for $B^{-}\to D^{\ast \ast 0}{\pi }^{-}$ agree with experiment. The sign of $D_1^{1\mathrm{/}2}-D_1^{3\mathrm{/}2}$ mixing angle is found to be positive in order to avoid a severe suppression on the production of $D_1(2427{)}^0{\pi }^{-}$. The interference between color-allowed and color-suppressed tree amplitudes is expected to be destructive in the decay $B^-\to D_1(2427)^0\pi^-$\mathrm{.}Hence,anobservationoftheratio$D_1(2427)^0\pi^-/D_1(2427)^+\pi^-$ can be used to test the relative signs of various form factors as implied by heavy quark symmetry. Although the predicted $B^{-}\to D_1(2420{)}^0{\rho }^{-}$ at the level of $3\times {10}^{-3}$ exceeds the present upper limit, it leads to the ratio $D_1(2420){\rho }^{-}\mathrm{/}{D}_1(2420){\pi }^{-}\approx 2.6$ as expected from the factorization approach and from the ratio $f_{\rho }\mathrm{/}{f}_{\pi }\approx 1.6$ . Therefore, it is crucial to have a measurement of this mode to test the factorization hypothesis. For $\bar{B}\to {\bar{D}}_s^{\ast \ast }D$ decays, it is expected that $\bar D_{s0}^D\gsim \bar D_{s1}D$asthedecayconstantsofthemultiplet$(D_{s0}^,D_{s1})$ become the same in the heavy quark limit.