Sonia Bacca

Brett Esry
Kansas State University

Lucas Platter
University of Washington

Program Coordinator:
Laura Lee
(206) 685-3509

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Weakly Bounds Systems in Atomic and Nuclear Physics

March 8 - 12, 2010


The goal of this workshop is to explore the connections between different theoretical methods used to model weakly bound few-body systems.

Nature shows the existence of weakly bound systems in different sectors, ranging from the atomic to the nuclear physics regime. We bring together practitioners from the nuclear physics and the AMO (atomic, molecular and optical) community to cross fertilize these fields.

Few-body systems with large scattering length exhibit universal features (universality), which are independent of the details of the interaction, and thus are common to nuclear and AMO systems.

In nuclear physics large scattering lengths are found in weakly bound systems like halo nuclei, which serve as nuclear examples of universality. Few-nucleon systems are another exmaple by themselves, since the two-nucleon scattering length is much larger than the range of the nucleon-nucleon interaction. Exact methods used to study few-nucleon systems are valuable to investigate weakly bound nuclei (halo and resonant states) either by an extension of ab-initio calculations towards larger mass number, or via the use of cluster models, where the core becomes a constituent of the nucleus. In atomic physics, experiments with ultra-cold atoms allow the tuning of the atomic two-body scattering length with an external magnetic field to arbitrary values and in particular to significantly larger values than the range of the atom-atom interaction. Recent experimental efforts have demonstrated that the implications of three- and four-body universality can be observed and are relevant for resonantly interacting Bose gases and Fermi gases with more than two spin states.

The common interest of the nuclear and atomic physics community in large scattering length systems is the driver for the workshop. To stimulate progress and crossfertilization, we envision focusing on the following topics:

  • Ab-initio Methods in Nuclei and AMO Systems
  • Cluster and EFT Approaches
  • Identification of Key Observables to Study

    Ab-initio Methods in Nuclei and AMO Systems

    Very different ab-initio approaches are used to calculate the properties of few-body systems, ranging from Faddeev methods to diagonalization methods that rely on an expansion of the wave functions in a complete basis set, like e.g. hyper-spherical harmonics and no core shell model. This workshop would provide an excellent opportunity to identify the advantages and disadvantages of the approaches employed by different groups.

    Cluster and EFT Approaches

    The properties of halo systems such as 6He are very often calculated by assuming that the core of the halo can be considered as a constituent and an effective potential is used to parameterize the interaction between core and halo nucleons. Ab-initio wave functions methods capable of calculating the nucleon-core scattering properties can therefore provide important input to improve the quality of these effective interactions.

    Identification of Key Observables to Study

    Weakly bound systems have attracted increasing attention in the theory community, triggered by recent advances in experimental measurements. An important goal we want to achieve with this workshop is an identification of observables that are required to be considered in the immediate future. First, we want to understand what different theoretical approaches can deliver. Second, we aim at determining which observable can be measured with the required accuracy.

    The following questions will be addressed during the workshop: What can we learn from neutron-rich nuclei about three-body forces? What are the limits of Efimov universality? How are universal features modified by the finite range of the underlying interaction? What are these universal features in systems of distinguishable particles with different masses? What are the universal features of the 5-body system? Can experiments with ultracold atoms, where the P-wave interaction can be tuned, provide insight into the physics of the neutron drip line?

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