3 research outputs found
Effective interactions for light nuclei: an effective (field theory) approach
One of the central open problems in nuclear physics is the construction of
effective interactions suitable for many-body calculations. We discuss a
recently developed approach to this problem, where one starts with an effective
field theory containing only fermion fields and formulated directly in a
no-core shell-model space. We present applications to light nuclei and to
systems of a few atoms in a harmonic-oscillator trap. Future applications and
extensions, as well as challenges, are also considered
Two and Three Nucleons in a Trap and the Continuum Limit
We describe systems of two and three nucleons trapped in a
harmonic-oscillator potential with interactions from the pionless effective
field theory up to next-to-leading order (NLO). We construct the two-nucleon
interaction using two-nucleon scattering information. We calculate the trapped
levels in the three-nucleon system with isospin and determine the
three-nucleon force needed for stability of the triton. We extract
neutron-deuteron phase shifts, and show that the quartet scattering length is
in good agreement with experimental data.Comment: 19 pages, 15 figure
Three and Four Harmonically Trapped Particles in an Effective Field Theory Framework
We study systems of few two-component fermions interacting via short-range
interactions within a harmonic-oscillator trap. The dominant interactions,
which are two-body, are organized according to the number of derivatives and
defined in a two-body truncated model space made from a bound-state basis.
Leading-order (LO) interactions are solved for exactly using the formalism of
the No-Core Shell Model, whereas corrections are treated as many-body
perturbations. We show explicitly that next-to-LO and next-to-next-to-LO
interactions improve convergence as the model space increases. We present
results at unitarity for three- and four-fermion systems, which show excellent
agreement with the exact solution (for the three-body problem) and results
obtained by others methods (in the four-body case). We also present results for
finite scattering lengths and non-zero range of the interaction, including (at
positive scattering length) observation of a change in the structure of the
three-body ground state and extraction of the atom-dimer scattering length.Comment: 18 pages, 10 figure