First observation of Λ_c(2595)⁺→Λc+π0π0 and Λ_c(2625)⁺→Λc+π0π0

By analysing e⁺e⁻ annihilation data corresponding to an integrated luminosity of 368.48 pb⁻¹ collected at the centre-of-mass energies of s = 4.918 and 4.951 GeV with the BESIII detector, we report the first observation of Λ_c(2595)⁺ and Λ_c(2625)⁺ → Λc+π0π0 with statistical significances of 7.9σ and 11.8σ, respectively. The branching fractions of Λ_c(2595)⁺ and Λ_c(2625)⁺ → Λc+π0π0 are measured to be (59.5 ± 11.1_stat. ± 7.9_syst.)% and (41.0 ± 5.2_stat. ± 3.3_syst.)%, respectively. The absolute branching fraction of Λ_c(2595)⁺ is consistent with the expectation of the mechanism referred to as the threshold effect, proposed for the strong decays of Λ_c(2595)⁺ within uncertainty.