Consistent chiral three-nucleon interactions in ... - Theory Center

SECTION 1
Introduction
From the point of view of low-energy nuclear structure physics, the atomic nu-
cleus is built of protons and neutrons, the so called nucleons. Quarks and gluons,
which represent the internal degrees of freedom of the nucleons, are not consid-
ered explicitly. The issue of nuclear structure physics is, on the one hand to make
precise predictions for experimental observables, e.g. binding and excitation en-
ergies and nucleon densities, which can also be used as input for further investi-
gations, e.g. in astrophysics. On the other hand, one is interested in a theoretical
framework which can describe the experimental properties of nuclei based on the
fundamental physics of the strong interaction.
In this thesis we pursue the strategy of solving the time-independent many-
body Schrödinger equation, which is equivalent to solving the eigenvalue problem
of the Hamilton operator. While the statement of the task is rather simple, two dif-
ficulties arise when we approach the eigenvalue problem. Firstly, only some basic
symmetry assumptions, e.g. rotational invariance, restrict the possible operator
structures in the nuclear interaction. Therefore, an appropriate interaction appli-
cable over a wide range of nuclei is still absent. Secondly, solving the many-body
problem itself is non-trivial, because it will turn out that we have to deal with large
model spaces to get valuable results.
Concerning the nuclear interaction, in the 1990s one assumed two-nucleon in-
teractions and accepted that irreducible interactions within triples of nucleons
were neglected. Prominent examples of these potentials are the Argonne-V18 or
CD-Bonn interactions, that reproduce nucleon-nucleon scattering data as well as
deuteron properties but contain lots of phenomenology.
Using these potentials for the calculation of spectra of various nuclei, one fails
to match experimental results. A well-known example for such failure is the ground
J. Langhammer 1