The Problem of Renormalization of Chiral Nuclear Forces

Understand

Ever since quantum field theory was first applied to the derivation of nuclear forces in the mid-20th century, the renormalization of pion exchange with realistic couplings has presented a challenge.

• The implementation of effective field theories (EFTs) in the 1990s promised a solution to this problem but unexpected obstacles were encountered.
• The response of the nuclear community has been to focus on "chiral potentials" with regulators chosen to produce a good description of data.
• Meanwhile, a successful EFT without explicit pion exchange --- Pionless EFT --- has been formulated where renormalization is achieved order by order in a systematic expansion of low-energy nuclear observables.