Improved action for contact effective field theory

0584753 - ÚJF 2025 RIV US eng J - Journal Article
Contessi, L. - Schäfer, Martin - van Kolck, U.
Improved action for contact effective field theory.
Physical Review A. Roč. 109, č. 2 (2024), č. článku 022814. ISSN 2469-9926. E-ISSN 2469-9934
R&D Projects: GA ČR(CZ) GA22-14497S
Institutional support: RVO:61389005
Keywords : Effective field theory * Few-body systems * Interactions
OECD category: Atomic, molecular and chemical physics (physics of atoms and molecules including collision, interaction with radiation, magnetic resonances, Mössbauer effect)
Impact factor: 2.9, year: 2022
Method of publishing: Limited access
https://doi.org/10.1103/PhysRevA.109.022814

We present an improved action for renormalizable effective field theories (EFTs) of systems near the two-body unitarity limit. The ordering of EFT interactions is constrained, but not entirely fixed, by the renormalization group. The remaining freedom can be used to improve the theory's convergence, to simplify its applications, and to connect it to phenomenological models. We exemplify the method on a contact theory applied to systems of up to five 4He atoms. We solve the EFT at leading order including a subleading interaction that accounts for part of the two-body effective range. We show that the effects of such fake range can be compensated in perturbation theory at next-to-leading order, as long as the fake range is smaller or comparable to the experimental effective range. These results open the possibility of using similar improved actions for other many-body systems.
Permanent Link: https://hdl.handle.net/11104/0352598