Strong interactions for precision nuclear physics
Title: Strong interactions for precision nuclear physics
SNIC Project: SNIC 2020/5-433
Project Type: SNIC Medium Compute
Principal Investigator: Andreas Ekström <>
Affiliation: Chalmers tekniska högskola
Duration: 2020-09-01 – 2021-09-01
Classification: 10301


The research in this proposal strives to make significant advances in the theoretical description of atomic nuclei. This project is now funded within an ERC Starting Grant (2018-2023) "PrecisionNucleo". In particular, we will study the prospects of describing atomic nuclei using effective field theories of QCD. Several aspects of this research will require HPC efforts: 1) exploring competing power-counting schemes in EFT 2) constraining the three-nucleon interaction in chiral EFT using three-nucleon scattering observables as well as recent isovector observables. Both efforts will play a crucial role for the description of unstable and exotic isotopes. Furthermore, the strength of the corresponding amplitudes, in particular of the three-neutron part, is currently very weakly constrained. This will have a dramatic impact on the correlations that determine the stability of neutron-rich matter. The computational problem corresponds to: - very fast computation of three-nucleon scattering observables (repeated matrix-vector products and matrix diagonalizations). - many-parameter optimization (up to 40 parameters) - large-scale matrix diagonalization (to solve the quantum mechanical many-body problem with strong interactions). Sparse MatVec and large VecVec operations. Our collaboration, that includes researchers in Scandinavia and the US, are currently pioneering such efforts and use state-of-the-art optimization methods at next-to-next-to-leading order to describe atomic nuclei. [G. Hagen et al. Nature Physics 12, 186–190 (2016) , R. F. Garcia Ruiz et al. Nature Physics. (2016) advanced publication online doi:10.1038/nphys3645]. In 2014-15 we have also implemented optimization with regards to nucleon-nucleon and pion-nucleon scattering observables, extracted covariance matrices and performed error propagation in the few-body sector using valuable computer time provided by SNIC/triolith. [B. D. Carlson et al, Phys. Rev. X 6, 011019]