Optimized nuclear forces from chiral effective field theory
Title: Optimized nuclear forces from chiral effective field theory
SNIC Project: SNIC 2013/1-282
Project Type: SNAC Medium
Principal Investigator: Christian Forssén <christian.forssen@chalmers.se>
Affiliation: Chalmers tekniska högskola
Duration: 2013-11-13 – 2014-12-01
Classification: 10301


Through the research contained in this proposal we want to make significant advances in the theoretical modeling of atomic nuclei. In particular, we will study chiral effective field theory as a tool to understand the nature of the strong nuclear force. Within this theoretical framework, the strong force between nucleons can be systematically derived in a power counting scheme as a series of pion-exchanges and contact interactions, with the well-known one-pion exchange at the leading order. In the past decade very precise models of the strong force resulted from this procedure by going to next-to-next-to-next-to-leading order, and atomic nuclei have indeed been computed from scratch based on this approach. In these models, three-nucleon forces play a smaller but pivotal role. Our collaboration, that includes researchers in Scandinavia and the US, has recently started to revisit these models and use state-of-the-art optimization methods to construct a high-precision potential already at next-to-next-to-leading order [A. Ekström et al. Phys. Rev. Lett. 110, 192502 (2013)]. The next steps in this ambitious research project include: optimization with regards to nucleon scattering observables, implementing higher orders in the chiral expansion, adding pion-nucleon data, extracting covariance matrices, error propagation, etc. The computational problem corresponds to: - very fast computation of nuclear scattering observables (many small MatMat operations). - many-parameter optimization (about 20-30 parameters) - large-scale matrix diagonalization (to solve the quantum mechanical many-body problem with strong interactions). Sparse MatVec and large VecVec operations.