E<scp>FFECTIVE</scp> F<scp>IELD</scp> T<scp>HEORY FOR</scp> F<scp>EW</scp>-N<scp>UCLEON</scp> S<scp>YSTEMS</scp>

TLDR

Effective field theories for few‑nucleon systems are controlled momentum expansions that, at low energies, employ contact interactions to study non‑perturbative renormalization and asymptotic behavior, and at higher energies incorporate pion fields to extend phenomenological potentials while preserving QCD symmetry links to lattice QCD. We review EFTs for few‑nucleon systems and discuss their tests and prospects. Model‑independent calculations to high orders yield high precision, and the EFTs’ tests and prospects are discussed.

Abstract

We review the effective field theories (EFTs) developed for few-nucleon systems. These EFTs are controlled expansions in momenta, where certain (leading-order) interactions are summed to all orders. At low energies, an EFT with only contact interactions allows a detailed analysis of renormalization in a non-perturbative context and uncovers novel asymptotic behavior. Manifestly model-independent calculations can be carried out to high orders, leading to high precision. At higher energies, an EFT that includes pion fields justifies and extends the traditional framework of phenomenological potentials. The correct treatment of QCD symmetries ensures a connection with lattice QCD. Several tests and prospects of these EFTs are discussed.