Renormalization of the leading-order chiral nucleon-nucleon interaction and bulk properties of nuclear matter

Understand

We renormalize the two-nucleon interaction at leading order (LO) in chiral perturbation theory using the scheme proposed by Nogga, Timmermans, and van Kolck--also known as modified Weinberg counting.

• With this interaction, we calculate the energy per nucleon of symmetric nuclear matter in the Brueckner pair approximation and obtain a converged, cutoff-independent result that shows saturation, but also substantial underbinding.
• We find that the renormalized LO interaction is characterized by an extraordinarily strong tensor force (from one-pion exchange), which is the major cause for the lack of binding.
• The huge tensor force also leads to the unusually large wound integral of 40% in nuclear matter, which implies a very slow convergence of the hole-line or coupled-cluster expansion, rendering this interaction impractical for many-body calculations.