Lifetimes of excited states in $$^{16}$$C as a benchmark for ab initio developments

Lifetimes of higher-lying states (2(2)(+ )and 4(1)(+)) in C-16 have been measured, employing the Gammasphere and Microball detector arrays, as key observables to test and refine ab initio calculations based on interactions developed within chiral Effective Field Theory. The presented experimental constraints to these lifetimes of tau(2(2)(+))=[244,446]fs and tau(4(1)(+)) = [1.8,4]ps, combined with previous results on the lifetime of the 2+1 state of C-16, provide arather complete set of key observables to benchmark the theoretical developments. We present No-Core Shell-Model cal-culations using state-of-the-art chiral 2- (NN) and 3-nucleon(3N) interactions at next-to-next-to-next-to-leading order forboth the NN and the 3N contributions and a generalizednatural-orbital basis (instead of the conventional harmonic-oscillator single-particle basis) which reproduce, for the firsttime, the experimental findings remarkably well. The levelof agreement of the new calculations as compared to theCD-Bonn meson-exchange NN interaction is notable andpresents a critical benchmark for theory. reproduce, for the first time, the experimental findings remarkably well. The level of agreement of the new calculations as compared to the CD-Bonn meson-exchange NN interaction is notable and presents a critical benchmark for theory.