Measurement of the branching fractions of the decays Λc+ → Λ KS0 K+, Λc+ → Λ KS0 π+, and Λc+ → Λk∗+

Studies are performed of the Cabibbo-favored decay Λc+→ΛKS0K+ and the singly Cabibbo-suppressed decay Λc+→ΛKS0π+, based on a sample of e+e- collision data, corresponding to an integrated luminosity of 4.5 fb-1, accumulated at center-of-mass energies between 4599.53 MeV and 4698.82 MeV with the BESIII detector. The decay Λc+→ΛKS0π+ is observed for the first time. The branching fractions of Λc+→ΛKS0K+ and Λc+→ΛKS0π+ are measured to be (3.04±0.30±0.16)×10-3 and (1.73±0.27±0.10)×10-3, respectively, where the first uncertainties are statistical and the second are systematic. These results correspond to the most precise measurement of these quantities for both decays. Evidence of a K∗+ contribution in the Λc+→ΛKS0π+ decay is found with a statistical significance of 4.71σ. The branching fraction of Λc+→ΛK∗+ is calculated under three possible interference scenarios, with the significance increasing to 5.03σ when interference is taken into account.