Study of Form Factors and Observables in $B_c^- \rightarrow \bar{D}^{(*)0}\ell^-\bar{\nu}_{\ell}$ and $B_c^- \rightarrow D^{(*)-}\ell^+\ell^-$ decays

We investigate the decays $B_c^- \rightarrow \bar{ D}^{ (*)0}\ell^-\bar{ \nu}_{ \ell}$ and $B_c^- \rightarrow D^{ (*)-}\ell^+\ell^-$ within the Standard Model (SM), employing perturbative QCD form factors that are sensitive to the wave functions of $B_c$ and $D^{ (*)}$ mesons. Using lattice QCD inputs for $B \to D^{ (*)}$ and $B_c \to D$ transitions, we extract the shape parameters of the meson wave functions and estimate the $q^2$-dependence of $B_c \to D^*$ form factors via heavy quark spin symmetry. We present predictions for branching fractions, lepton flavor violating observables, and perform a detailed angular analysis of the cascade decay $B_{ c}^{ -} \to D^{ *-}(\to D^{ 0}\pi^{ -}) \ell^+\ell^-$, providing SM expectations for several angular observables.

Categories: hep-ph