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Organizers
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Coordinator |
Nuclear forces form the basis for our comprehension of nuclear
structure and reactions. In the 50 years since the discovery
of the pion, progress in understanding the two-nucleon interaction and
consistent few-nucleon forces has been slow and difficult. In particular, the
connection to the 25-year-old theory of the strong interaction, quantum
chromodynamics (QCD), remains an enigma. However,
the last few years have witnessed
important advances that opened doors to a better understanding
of the nuclear force.
Novel partial-wave analysis methods that incorporate the rich
two-nucleon database can now be
used as a sensitive tool to study small but important effects, such
as those stemming from two-pion exchange and isospin violation.
These methods have in the past inspired high-quality potentials
that almost exactly reproduce
the two-nucleon data, but which are not fully in accordance with
chiral symmetry.
Few-body calculations are being performed to
unprecedent precision and used as a genuine source of information
about the nuclear force. In particular, they are now sensitive to
both two-pion-exchange and short-range aspects of the three-body force.
At the same time, the consistency of
electromagnetic currents and the hunt for effects of the three-body
force have become important issues in the few-nucleon field.
Experiments have already suggested the need for three-body forces;
more comprehensive efforts are underway in a number of laboratories.
Finally, an effective field theory (EFT) approach
is being developed to allow systematic expansions consistent with
QCD. Such an approach incorporates chiral symmetry
and overcomes the renormalizability problems
encountered in the fifties, removing at the same
time the off-shell arbitrariness
that plagues few-nucleon calculations to
this day.
The connections between EFT and potential models are not yet fully
clarified, and important features like the most efficient power
counting remain to be determined by further confrontation
with data.
The workshop will focus on our current understanding of nuclear forces,
in particular:
The two-pion exchange component of
the two-nucleon force and its relation to low-energy
pion-nucleon and pion-pion scattering:
implications of chiral
symmetry; the role of the Delta isobar;
the nature of the ``sigma'' meson.
Short-range aspects of the nuclear force:
contact interactions versus bosons;
regularization issues.
Few-body constraints on the nuclear force:
ab initio calculations of light nuclei
and nucleon-deuteron and nucleon-triton scattering;
towards consistent three-nucleon interactions
and incorporating relativity correctly.
Isospin violation in the nuclear force:
strong and electromagnetic effects.
Formulation of consistent meson-exchange currents.
Attending
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(The number of participants is
limited to facilitate intense discussion.)
A
schedule
exists.
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