1,238 research outputs found
Electroweak reactions with light nuclei
The investigation of light nuclei with ab-initio methods provides an optimal
setting to probe our knowledge on nuclear forces, because the few-nucleon
problem can be solved accurately. Nucleons interact not only in pairs but also
via many-body forces. Theoretical efforts need to be taken towards the
identification of nuclear observables sensitive to the less known many-nucleon
forces. Electromagnetic reactions can potentially provide useful information on
this. We present results on photo-absorption and electron scattering off light
nuclei, emphasizing the role of three-body forces and the comparison with
experimental data. On the other hand, reactions induced by weak probes, like
neutrino interactions with nucleonic matter, are relevant to astrophysics and
can be calculated with few-body techniques. In this case, since often no
experiment is possible, ab-initio predictions provide valuable input for
astrophysical simulations.Comment: 17 pages, 17 figures, Proceedings of the 19th International IUPAP
Conference on Few-Body Problems in Physics, Aug. 31 - Sept. 5, 2009, Bonn,
German
Ab initio calculation of Li7 photodisintegration
The Li7 total photoabsorption cross section is calculated microscopically. As
nucleon-nucleon interaction the semi-realistic central AV4' potential with S-
and P-wave forces is taken. The interaction of the final 7-nucleon system is
fully taken into account via the Lorentz Integral Transform (LIT) method. For
the calculation of the LIT we use expansions in hyperspherical harmonics (HH)
in conjunction with the HH effective interaction (EIHH) approach. The
convergence of the LIT expansion is discussed in detail. The calculated cross
section agrees quite well with the available experimental data, which cover an
energy range from threshold up to 100 MeV.Comment: 11 pages with 3 figure
Emission of neutrino-antineutrino pairs by hadronic bremsstrahlung processes
We review our recent calculations of neutrino-antineutrino pair production
from bremsstrahlung processes in hadronic collisions at temperature and
densities relevant for core-collapse supernovae. We focus on neutron-neutron
and neutron-alpha collisions.Comment: 8 pages, 4 figures, proceedings of the NN2015 conference, Catania,
21-26 June, 201
Long Range Tensor Correlations in Charge and Parity Projected Fermionic Molecular Dynamics
Within the framework of Fermionic Molecular Dynamics a method is developed to
better account for long range tensor correlations in nuclei when working with a
single Slater determinant. Single-particle states with mixed isospin and broken
parity build up an intrinsic Slater determinant which is then charge and parity
projected. By minimizing the energy of this many-body state with respect to the
parameters of the single-particle states and projecting afterwards on angular
momentum ground state energies are obtained that are systematically lower than
corresponding Hartree-Fock results. The realistic Argonne V18 potential is used
and short range correlations are treated with the Unitary Correlation Operator
Method. Comparison with exact few-body calculations shows that in He about
one fifth of the correlation energy due to long-range correlations are
accounted for. These correlations which extend over the whole nucleus are
visualized with the isospin and spin-isospin density of the intrinsic state.
The divergence of the spin-isospin density, the source for pion fields, turns
out to be of dipole nature.Comment: 12 pages, 4 figure
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