(University of Arizona)
(Louisiana State University)
(University of Gent)
P. van Isacker
Workshop on New Approaches in Nuclear Many-Body Theory
Workshop on Correlations in Nuclei: From Di-nucleons to Clusters
Nuclear Many-Body Approaches for the 21st Century |
September 24 - November 30, 2007
The goal of our program is to bring together leading researchers in
microscopic few-body and many-body theories to think and to discuss
outside the same old boxes that have been used in the past, and to
develop new ways and a new strategy to attack the nuclear many-body
problem. Of particular interest is the determination of new ways to
include many more correlations among the nucleons when calculations are
performed in smaller or restricted model spaces, and especially how to
accommodate special symmetries into the theory.
For example, we plan to bring together shell-model theorists with
researchers doing symplectic and cluster calculations to look for ways to
accommodate these into a more comprehensive theory, i.e., how does
collective rotational motion and clustering emerge in shell-model
calculations. Theorists using group theory and cluster techniques will
be brought into these discussions to study whether it is possible to
to propose truncation schemes of the shell model based on symmetries
and also to explore new methods to use group-theoretical techniques
to model the nuclear many-body problem.
Another topic for extended discussion will be the role of the continuum in
weakly-bound systems. This is of particular relevance in nuclei away from
the stability line where all states are close to the neutron or proton
separation threshold and effects of the continuum may play a crucial role
in the phenomena, such as two-proton radioactivity. And again, the role
of special symmetries in the treatment of "open" quantum systems needs
to be investigated, in particular with regard to relevant non-compact
A further focus will be on fostering exchanges among many-body theorists
working on symplectic methods, the coupled-cluster approach, the Green
function formalism, Monte Carlo methods, and unitary transformations of
nuclear operators to investigate new ways to apply their schemes and
build them into a more comprehensive many-body theory, e.g.,
through multiple unitary transformations or multiple effective model-space
And, since through Effective Field Theory (EFT) it is now possible
to link QCD physics directly to shell-model effective interactions and
other physical operators in a truncated model space, ways to pursue
and further develop this connection will be another major topic of our
The program would address the following issues, among others:
2. Theoretical Issues:
The nature of the NN potential: CPT potentials vs empirical
- Three-nucleon interactions, particularly those based on CPT.
- The application of these NN and NNN potentials to
- Evidence for or against the need for higher-rank potentials, and,
in particular, the possible importance of NNNN correlations in
- The modification of these potentials inside the nuclear medium,
i.e., what is the structure of the renormalized or
effective interaction needed for nuclear-structure calculations,
particularly for heavier nuclei?
3. Computational Issues:
Linkages among QCD, lattice gauge calculations, EFT/CPT and nuclear
- Consistent treatment of regulators/cutoffs between the 2/3-body
systems and the many-body systems.
- The structure of other effective operators, such as the radius,
the quadrupole moment, etc.
- Development of new many-body approaches for including more
NN correlations in small model spaces.
- Combining shell-model, cluster and group-theory techniques into
an unified approach to nuclear-structure calculations.
- How to combine the bound and weakly-bound nuclear regimes: merging of
standard nuclear shell-model methods and nuclear-reaction technology.
Discussion of the different available approaches
and the possible role of symmetries in their treatment.
As a general guide, we like to stress the importance of having input from
experimentalists in order to focus the discussion and to confront
theoretical attempts with constraints from state-of-the-art experiments
on nuclear structure. As such, we encourage applications from
experimentalists. A mixed audience of theorists and experimentalists is
a necessary element in order to have a successful program.
What scope of physics applications will be possible with
the present and next generation of interactions/algorithms/computers?
- Benchmark comparisons of different many-body methods,
as well as efficiency tests.
- Assessments of the rate of convergence of different
numerical techniques for computing nuclear properties.
During the second or third week of the program, a one-week workshop may be
organized, so as to bring together as many of the key participants
in this field as possible to discuss and define the important issues to
be investigated during the rest of the program.