Search for Charmed Baryons in the Λ_c^+η System and Measurement of the Branching Fractions of Λ_c(2880)^+ and Λ_c(2940)^+ Decaying to Λ_c^+η and Pd^0 Relative to Σ_c(2455)π

We search for excited charmed baryons in the Λ_c^+η system using a data sample corresponding to an integrated luminosity of 980 fb^-1. The data were collected by the Belle detector at the KEKB e^+e^- asymmetric-energy collider. No significant signals are found in the Λ_c^+η mass spectrum, including the known Λ_c(2880)^+ and Λ_c(2940)^+. Clear Λ_c(2880)^+ and Λ_c(2940)^+ signals are observed in the pD^0 mass spectrum. We set upper limits at 90% credibility level on ratios of branching fractions of Λ_c(2880)^+ and Λ_c(2940)^+ decaying to Λ_c^+η relative to Σ_c(2455)π of <0.13 for the Λ_c(2880)^+ and <1.11 for the Λ_c(2940)^+. We measure ratios of branching fractions of Λ_c(2880)^+ and Λ_c(2940)^+ decaying to pD^0 relative to Σ_c(2455)π of 0.75 ± 0.03(stat.) ± 0.07(syst.) for the Λ_c(2880)^+ and 3.59 ± 0.21(stat.) ± 0.56(syst.) for the Λ_c(2940)^+.