Covariant Light-Front Approach for $B_c$ transition form factors

Understand

In the covariant light-front quark model, we investigate the form factors of $B_c$ decays into $D, D^*, D_s, D_s^*, \eta_c, J/\psi, B, B^*, B_s, B_s^*$ mesons.

• The form factors in the spacelike region $q^2<0$ are directly evaluated.
• To extrapolate the form factors to the full kinematic region, we fit the form factors by adopting a three-parameter form from the spacelike region.
• $b\to u,d,s$ transition form factors at maximally recoiling point ($q^2=0$) are smaller than $b\to c$ and $c\to d,s$ transition form factors, while the $b\to d,s,c$ form factors at zero recoiling point are close to each other.