Nuclear effective field theory: status and perspectives (1906.12122v2)

Abstract: The nuclear physics landscape has been redesigned as a sequence of effective field theories (EFTs) connected to the Standard Model through symmetries and lattice simulations of Quantum Chromodynamics (QCD). EFTs in this sequence are expansions around different low-energy limits of QCD, each with its own characteristics, scales, and ranges of applicability regarding energy and number of nucleons. We review each of the three main nuclear EFTs -- Chiral, Pionless, Halo/Cluster -- highlighting their similarities, differences, and connections. In doing so, we survey the structural properties and reactions of nuclei that have been derived from the ab initio solution of the few- and many-body problem built upon EFT input.

• The paper presents nuclear EFTs as a systematic framework that links QCD with nuclear observables across different energy regimes.
• It details the use of Chiral, Pionless, and Halo EFTs to achieve precise predictions in nucleon scattering, reactions, and binding energies.
• The study highlights future prospects by integrating advanced computational methods and lattice QCD to extend EFT applications to heavier nuclei.

Overview of Nuclear Effective Field Theory

The paper "Nuclear Effective Field Theory: Status and Perspectives" presents a comprehensive review of the application of effective field theories (EFTs) within nuclear physics. The authors, H.-W. Hammer, Sebastian König, and U. van Kolck, offer insights into the conceptual developments and implications of nuclear EFT, focusing on the interplay between different scales and effective theories in describing nuclear phenomena.

Key Features of Nuclear Effective Field Theory

The core idea of nuclear EFT is to connect nuclear physics to the Standard Model of particle physics through a sequence of systematic, scale-dependent approximations. These approximations rely on identifying dominant interactions at specific energy regimes while accounting for the symmetries of the underlying theory, Quantum Chromodynamics (QCD). Nuclear EFTs bridge QCD predictions with observable phenomena in atomic nuclei, enabling precise calculations for complex nuclear systems.

Types of Nuclear EFTs

The paper categorizes nuclear EFTs into three primary forms based on their applicability and the scales they address:

1. Chiral EFT: This theory includes explicit pion fields and derives interactions between nucleons from chiral symmetry considerations. Chiral EFT is applicable at energy scales around the pion mass, where pion exchanges dominate nuclear forces.
2. Pionless EFT: Suitable for very low-energy nuclear interactions where pion exchanges are not resolved, and short-range interactions between nucleons are described by contact terms. This theory is particularly effective for systems like halo nuclei and other weakly bound nuclear states.
3. Halo/Cluster EFT: This framework extends Pionless EFT to describe nuclei with clustering of nucleons, such as two-neutron halos or complex multi-nucleon systems. It captures universal effects even in systems characterized by interactions at long distances.

Numerical Results and Bold Claims

The paper provides strong numerical results regarding EFT applications that successfully describe nuclear observables across different regimes. For instance, Chiral EFT has achieved considerable success in predicting nucleon-nucleon scattering parameters, nuclear reactions, and binding energies of light nuclei to a high degree of precision. The approach has also enabled systematic error estimates and improvements in nuclear models, integrating insights from ab initio calculations and lattice QCD results.

Implications and Future Prospects

Nuclear EFT has profound practical implications for nuclear structure calculations and reactions, offering flexibility and robustness in handling complex nuclear systems. By laying out a rigorous framework, nuclear EFT has opened pathways to exploring beyond-the-Standard-Model physics through nuclear processes, such as searches for parity-violating interactions or neutrinoless double-beta decay.

Looking forward, the paper speculates on the direction of future developments in nuclear EFT, emphasizing the integration of more degrees of freedom in computations and possibly extending EFT applications to heavier nuclei. Advances in computational methods and lattice QCD output are expected to refine the predictions and broaden the scope of nuclear EFT.

Conclusion

In summary, the paper underscores the pivotal role of nuclear EFT in bridging fundamental particle physics with observable nuclear phenomena. By leveraging the power of EFTs, researchers can systematically tackle complex nuclear systems, offering predictive capabilities and insights that enhance our understanding of matter at the smallest scales. As computational methods evolve and experimental techniques advance, nuclear EFTs will likely become increasingly essential in nuclear physics research and related fields.