Exact emulation of few-body systems at low cost

Fuente: arXiv
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Main Authors: Heihoff, Sven, Filin, Arseniy A., Epelbaum, Evgeny
Format: Preprint
Published: 2026
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author Heihoff, Sven
Filin, Arseniy A.
Epelbaum, Evgeny
author_facet Heihoff, Sven
Filin, Arseniy A.
Epelbaum, Evgeny
contents Effective field theories have established themselves as key pillars of modern nuclear physics. They enable a quantitative understanding of the strong nuclear force, provided low-energy constants that parametrize short-distance physics can be determined from experimental data. This, however, often becomes prohibitively expensive due to a significant computational cost of solving the A-body problem. The computational challenge is particularly severe for three-body forces, which are at the frontier of nuclear and atomic physics and play an important role in the equation of state of neutron stars. Here we prove that for a parametric low-rank update of a Hamiltonian, the A-body problem at a fixed energy exactly reduces to a low-dimensional matrix equation regardless of the size of the Hilbert space. As a proof-of-principle, we present exact and computationally cheap snapshot-based emulators for few-body scattering and bound states. Unlike alternatives, our emulators can be used far away from the snapshot region without loss of precision and yield accurate results for parameter values not accessible using conventional solution techniques. Our approach is not restricted by the interaction type, number of particles, and methods for generating snapshots and can be applied to mitigate the computational burden of the A-body problem to a broad class of problems in nuclear, atomic, and molecular physics.
format Preprint
id arxiv_https___arxiv_org_abs_2604_25792
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Exact emulation of few-body systems at low cost
Heihoff, Sven
Filin, Arseniy A.
Epelbaum, Evgeny
Nuclear Theory
High Energy Physics - Phenomenology
Effective field theories have established themselves as key pillars of modern nuclear physics. They enable a quantitative understanding of the strong nuclear force, provided low-energy constants that parametrize short-distance physics can be determined from experimental data. This, however, often becomes prohibitively expensive due to a significant computational cost of solving the A-body problem. The computational challenge is particularly severe for three-body forces, which are at the frontier of nuclear and atomic physics and play an important role in the equation of state of neutron stars. Here we prove that for a parametric low-rank update of a Hamiltonian, the A-body problem at a fixed energy exactly reduces to a low-dimensional matrix equation regardless of the size of the Hilbert space. As a proof-of-principle, we present exact and computationally cheap snapshot-based emulators for few-body scattering and bound states. Unlike alternatives, our emulators can be used far away from the snapshot region without loss of precision and yield accurate results for parameter values not accessible using conventional solution techniques. Our approach is not restricted by the interaction type, number of particles, and methods for generating snapshots and can be applied to mitigate the computational burden of the A-body problem to a broad class of problems in nuclear, atomic, and molecular physics.
title Exact emulation of few-body systems at low cost
topic Nuclear Theory
High Energy Physics - Phenomenology
url https://arxiv.org/abs/2604.25792