Strong interactions for precision nuclear physics
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]