Using the topological-diagram approach based on SU(3) flavor symmetry, we investigate two-body \( {\Lambda}_c^{+}\to \textbf{B}S \) decays, where B denotes the final-state baryon and S refers to a light scalar meson, such as f0/f0(980), a0/a0(980), σ0/f0(500), or \( \kappa /{K}_0^{\ast }(700) \) . Our analysis indicates that interpreting the light scalar mesons as tetraquark states provides a more consistent description of the currently available experimental data. In particular, this framework naturally accommodates the experimentally observed branching fraction \( \mathcal{B}\left({\Lambda}_c^{+}\to \Lambda {a}_0^{+}\right) \) , which exceeds predictions based solely on long-distance effects by an order of magnitude. Within the tetraquark scenario, we predict \( \mathcal{B}\left({\Lambda}_c^{+}\to {\Sigma}^{+}{f}_0\right)=\left(4.9\pm 1.9\right)\times {10}^{-2} \) and \( \mathcal{B}\left({\Lambda}_c^{+}\to p{f}_0\right)=\left(3.6\pm 1.4\right)\times {10}^{-3} \) . Owing to f0 − σ0 mixing, \( \mathcal{B}\left({\Lambda}_c^{+}\to {\Sigma}^{+}{\sigma}_0\right) \) and \( \mathcal{B}\left({\Lambda}_c^{+}\to p{\sigma}_0\right) \) are suppressed to the levels of 1 × 10−3 and 5 × 10−5, respectively. These modes therefore provide sensitive probes of the internal structure of the light scalar mesons. More generally, the remaining branching ratios of \( {\Lambda}_c^{+}\to \textbf{B}S \) are found to be comparable to those of \( {\Lambda}_c^{+}\to \textbf{B}M \) , where M denotes a pseudoscalar meson. Their predicted sizes suggest that these decay modes should be accessible to ongoing and near-future experimental studies at BESIII, Belle II, and LHCb.
