Eur. Phys. J. A (2024) 60: 181
https://doi.org/10.1140/epja/s10050-024-01396-2

Regular Article – Experimental Physics

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

¹ Institut für Kernphysik, Technische Universität Darmstadt, Darmstadt, Germany
² School of Physics, Engineering and Technology, University of York, Heslington, York, UK
³ Physics Division, Argonne National Laboratory, Argonne, IL, USA
⁴ Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
⁵ Chemistry Department, Washington University, St. Louis, MO, USA
⁶ Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
⁷ Department of Physics, Florida State University, Tallahassee, FL, USA
⁸ SSC Laboratory, iThemba LABS, PO Box 722, Somerset West, South Africa
⁹ School of Physics, University of the Witwatersrand, Johannesburg, South Africa
¹⁰ Department of Physics and Astronomy, University of North Carolina at Chapel Hill, 27599, Chapel Hill, NC, USA
¹¹ Triangle Universities Nuclear Laboratory, Duke University, 27708, Durham, NC, USA
¹² Dipartimento di Fisica, Università degli Studi di Milano and INFN Sez. Milano, Milano, Italy

^b marina.petri@york.ac.uk

Received: 23 November 2023
Accepted: 12 August 2024
Published online: 12 September 2024

Abstract

Lifetimes of higher-lying states ($2_2^{+}$ and $4_1^{+}$) in $_{}^{16}$C 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 $\tau (2_2^{+})=[244,446]\text{fs}$ and $\tau (4_1^{+})=[1.8,4]\text{ps}$, combined with previous results on the lifetime of the $2_1^{+}$ state of $_{}^{16}$C, provide a rather complete set of key observables to benchmark the theoretical developments. We present No-Core Shell-Model calculations using state-of-the-art chiral 2- (NN) and 3-nucleon (3N) interactions at next-to-next-to-next-to-leading order for both the NN and the 3N contributions and a generalized natural-orbital basis (instead of the conventional harmonic-oscillator single-particle basis) which 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.