First observation of Λc(2595)+ → $ {\Lambda}_c^{+}{\pi}^0{\pi}^0 $ and Λc(2625)+ → $ {\Lambda}_c^{+}{\pi}^0{\pi}^0 $

By analysing e + e − annihilation data corresponding to an integrated luminosity of 368.48 pb −1 collected at the centre-of-mass energies of $\sqrt{s}$ = 4.918 and 4.951 GeV with the BESIII detector, we report the first observation of Λ c (2595)+ and Λ c (2625)+ → ${\Lambda}_c^{+}{\pi}^0{\pi}^0$ with statistical significances of 7.9σ and 11.8σ, respectively. The branching fractions of Λ c (2595)+ and Λ c (2625)+ → ${\Lambda}_c^{+}{\pi}^0{\pi}^0$ are measured to be (59.5 ± 11.1stat. ± 7.9syst. )% and (41.0 ± 5.2stat. ± 3.3syst. )%, 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.