Organizers:
B.R. Barrett
(University of Arizona)
bbarrett@physics.arizona.edu
J.P. Draayer (Louisiana State University)
draayer@lsu.edu
K. Heyde (University of Gent)
kris.heyde@ugent.be
P. van Isacker
(GANIL)
isacker@ganil.fr
Program Coordinator: Darlette Powell
darlette@phys.washington.edu
(206) 6854286
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Workshop on New Approaches in Nuclear ManyBody Theory
Workshop on Correlations in Nuclei: From Dinucleons to Clusters
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Nuclear ManyBody Approaches for the 21st Century
September 24  November 30, 2007
The goal of our program is to bring together leading researchers in
microscopic fewbody and manybody 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 manybody
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 shellmodel 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 shellmodel
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 grouptheoretical techniques
to model the nuclear manybody problem.
Another topic for extended discussion will be the role of the continuum in
weaklybound 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 twoproton 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 noncompact
group structures.
A further focus will be on fostering exchanges among manybody theorists
working on symplectic methods, the coupledcluster 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 manybody theory, e.g.,
through multiple unitary transformations or multiple effective modelspace
Hamiltonians.
And, since through Effective Field Theory (EFT) it is now possible
to link QCD physics directly to shellmodel 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
program.
The program would address the following issues, among others:
1. Potentials: 
The nature of the NN potential: CPT potentials vs empirical
potentials.
 Threenucleon interactions, particularly those based on CPT.
 The application of these NN and NNN potentials to
nuclearstructure calculations.
 Evidence for or against the need for higherrank potentials, and,
in particular, the possible importance of NNNN correlations in
nuclei.
 The modification of these potentials inside the nuclear medium,
i.e., what is the structure of the renormalized or
effective interaction needed for nuclearstructure calculations,
particularly for heavier nuclei?
2. Theoretical Issues:
Linkages among QCD, lattice gauge calculations, EFT/CPT and nuclear
structure calculations.
 Consistent treatment of regulators/cutoffs between the 2/3body
systems and the manybody systems.
 The structure of other effective operators, such as the radius,
the quadrupole moment, etc.
 Development of new manybody approaches for including more
NN correlations in small model spaces.
 Combining shellmodel, cluster and grouptheory techniques into
an unified approach to nuclearstructure calculations.
 How to combine the bound and weaklybound nuclear regimes: merging of
standard nuclear shellmodel methods and nuclearreaction technology.
Discussion of the different available approaches
and the possible role of symmetries in their treatment.
3. Computational Issues:
What scope of physics applications will be possible with
the present and next generation of interactions/algorithms/computers?
 Benchmark comparisons of different manybody methods,
as well as efficiency tests.
 Assessments of the rate of convergence of different
numerical techniques for computing nuclear properties.
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 stateoftheart 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.
During the second or third week of the program, a oneweek 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.
