Study of Form Factors and Observables in $B_c^- \rightarrow D_{s}^{*-}\ell^+\ell^-$ and $B_c^- \rightarrow D_{s}^{*-}ν\barν$ decays

We investigate the decays $B_c^- \rightarrow D_{s}^{(*)-}\ell^+\ell^-$ and $B_c^- \rightarrow D_{s}^{(*)-}ν\barν$ within the Standard Model (SM), employing perturbative QCD (pQCD) form factors that are sensitive to the wave functions of $B_c$ and $D_{s}^{(*)}$ mesons. We determine the shape paramete