Organizers:
Nir Barnea
Hebrew University
nir@phys.huji.ac.il

Dean Lee
North Carolina State University
dean_lee@ncsu.edu

Lucas Platter
Chalmers University of Technology,
Argonne National Laboratory platter@chalmers.se

Program Coordinator:
Inge Dolan
inge@uw.edu
(206) 685-4286

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INT Program INT-12-3

Light nuclei from first principles

September 17 - November 16, 2012


Overview

The past decade has been revolutionary for nuclear physics. We have seen the emergence of new and improved theories and computational methods leading to remarkable progress in our understanding of the nuclear force and our ability to describe nuclei from first principles. In this pursuit, the study of light nuclei provides an important challenge and testing ground. In this nine-week program dedicated to the physics of light nuclei we address the following topics:
  • Effective field theories for nuclear forces
  • Few body systems
  • Nuclear structure
  • Ab initio methods
  • Electroweak properties

Effective field theories (EFT's) have improved our understanding of the nuclear force, enabling precise calculations of observables in few-nucleon systems. EFT's connect the nuclear force to the underlying microscopic theory of quantum chromodynamics. In the future it will be possible to extract the parameters of nuclear EFT's directly from lattice QCD simulations.

New computational methods and increased computational power with parallel supercomputers have made possible ab initio calculations for systems well beyond just a few nucleons. Complementary to these large system calculations, high precision few-body calculations provide benchmark tests of our understanding of the nuclear forces and higher-body interactions.

Electroweak observables provide additional benchmarks and are important input to many other applications. This includes astrophysical processes such as big bang and stellar nucleosynthesis as well as scattering observables for nuclei used in beam targets and neutrino detectors. Accurate description of electroweak observables and reactions requires not only an accurate nuclear Hamiltonian but also nuclear currents consistent with that Hamiltonian. EFT provides a theoretical framework for the derivation of the force and current.

Workshops

Two workshops are planned during the course of the program

  • Week 4: Oct. 8 - Oct. 12, "Structure of light nuclei"
    This workshop aims to explore nuclear structure, nuclear forces, and ab initio methods.
    (Organizers: Dean Lee, Petr Navratil, Thomas Papenbrock)   Website

    There is a registration fee of $50 to attend this workshop. You may pay in cash - exact change preferred - or by a check drawn on a U.S. bank. Sorry, we cannot accept credit cards.

  • Week 8: Nov. 5 - Nov. 9 "Electroweak properties of light nuclei"
    This workshop will investigate electroweak properties of light nuclei in connection
    with recent and future experiments.
    (Organizers: Nir Barnea, Jerry Feldman, Lucas Platter)   Schedule

    There is a registration fee of $45 to attend this workshop. You may pay in cash - exact change preferred - or by a check drawn on a U.S. bank. Sorry, we cannot accept credit cards.

Some questions to be addressed

Effective field theory for nuclear forces

  • Can EFT potentials describe the properties of light nuclei?
  • Can EFT be extended to the momentum scale of nuclear matter?
  • Light nuclei are sensitive to several different momentum scales. Can we nonetheless obtain a priori estimates for observables of light nuclei?
  • Can a high precision EFT potential be constructed for ab initio calculations while simultaneously describing the pion mass dependence of the nuclear force?
  • What further input is needed for calculations of hypernuclei and EFT applied to hyperon-nucleon and hyperon-hyperon potentials?

    • Ab initio methods

  • What can be done to overcome computational limits on particle number?
  • How can EFT potentials be adapted for use in quantum Monte Carlo methods?
  • What role will the various methods (no-core shell model, coupled cluster, quantum Monte Carlo, correlated Gaussians, auxiliary field diffusion Monte Carlo, lattice effective field theory, lattice QCD, etc.) play in future nuclear structure calculations?
  • How shall we address reaction processes in a continuum that contains both narrow and wide resonances?
  • What new problems can we now solve that were impossible several years ago?
  • How general and robust are the methods and what are the systematic errors? Can a priori error estimates be made?
  • What new algorithms can be transferred or adapted from one method to another?
  • How can raw data such as nuclear wavefunctions produced in large-scale calculations be used by the larger theory community?
  • How can ab initio calculations assist lattice QCD calculations of the low-energy EFT parameters?

    • Electroweak properties

  • Are there any further interconnections between the parameters of the nuclear Hamiltonian and currents?
  • There are indications that EFT-based currents can explain the observed quenching of g_A in large nuclei. To what extent can ab initio calculations test this explanation?
  • What are the most probing observables to pin down the nuclear Hamiltonian and currents?
  • What additional information about higher-body forces can be obtained from electroweak observables?
  • Can EFT's be used to describe electron scattering at medium and high energies?

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