Radiative B→K1B\to K_1 decays in the light-cone sum rules

The weak form factor for $B\to K_{1B}$ where $K_{1B}$ is the $^1P_1$ state is calculated in the light-cone sum rules (LCSR). Combining the quark model result for the form factor of $B\to K_{1A}$ with $K_{1A}$ being the $^3P_1$ state, we have larger values for $B\to K_1$ form factors than the previous LCSR results. The increased form factors reduce the discrepancy between theory and the experimental data for $B\to K_1 \gamma$. Some phenomenological meanings are also discussed.Comment: 15 pages, 4 figure

Nonleptonic B decays into a charmed tensor meson

In the framework of the factorization and the heavy quark effective theory, $B\to D_2^*\pi$ modes are analyzed. We adopt the result from the QCD sum rule calculation for the hadronic matrix elements at leading order of $\Lambda_{\rm QCD}/m_Q$ and $\alpha_s$. The QCD sum rule results are well compatible with the current data, with the prediction on the branching ratios \calB(\Bbar^0\to D_2^{*+}\pi^-)=8.94\times 10^{-4} and \calB(B^-\to D_2^{*0}\pi^-)=9.53\times 10^{-4} for $N_C^{\rm eff}=2$. We give constraints on the interception $\tau(1)$ and the slope parameter $\rho^2$ of the leading Isgur-Wise function from the experimental bounds. It is argued that the observation of nonzero \calB(\Bbar^0\to D_2^{*0}\pi^0) directly measures the nonfactorizable effets.Comment: More discussions, references added, to appear in Eur. Phys. J.