Investigating the color-suppressed decays <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi mathvariant="normal">Λ</mml:mi><mml:mi>b</mml:mi></mml:msub><mml:mo stretchy="false">→</mml:mo><mml:mi mathvariant="normal">Λ</mml:mi><mml:mi>ψ</mml:mi></mml:math> in the perturbative QCD approach

The nonleptonic two-body ${\mathrm{\ensuremath{\Lambda}}}_{b}\ensuremath{\rightarrow}\mathrm{\ensuremath{\Lambda}}\ensuremath{\psi}$ decays with $\ensuremath{\psi}=J/\ensuremath{\psi}$ or $\ensuremath{\psi}(2S)$ are investigated based on the perturbative QCD approach. These color-suppressed processes in which nonfactorizable contributions confirmed to be dominant. Angular momentum conservation allows us describe concerned by four independent complex helicity amplitudes. It is observed that negative-helicity states for $\mathrm{\ensuremath{\Lambda}}$ baryon preferred as expected left-handed nature of charged-current interaction. obtained results amplitudes used compute branching ratios and various observable parameters, then compared existing theoretical predictions experimental data. In particular, we predict ratio $\mathcal{R}=\frac{\mathcal{B}({\mathrm{\ensuremath{\Lambda}}}_{b}\ensuremath{\rightarrow}\mathrm{\ensuremath{\Lambda}}\ensuremath{\psi}(2S))}{\mathcal{B}({\mathrm{\ensuremath{\Lambda}}}_{b}\ensuremath{\rightarrow}\mathrm{\ensuremath{\Lambda}}J/\ensuremath{\psi})}=0.4{7}_{\ensuremath{-}0.00}^{+0.02}$ comparison $0.508\ifmmode\pm\else\textpm\fi{}0.023$ from Particle Data Group at level 1 standard deviation. We also briefly explore long-distance semileptonic ${\mathrm{\ensuremath{\Lambda}}}_{b}\ensuremath{\rightarrow}\mathrm{\ensuremath{\Lambda}}{l}^{+}{l}^{\ensuremath{-}}$ kinematic regions where dilepton invariant masses around $J/\ensuremath{\psi}$ resonances.