Optimized nuclear forces from chiral effective field theory
||Optimized nuclear forces from chiral effective field theory|
||Christian Forssén <email@example.com>|
||Chalmers University of Technology|
||2013-11-13 – 2014-12-01|
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.