Speaker
Description
The key ingredient for mean-field calculations in nuclear structure is the
effective interaction which models the strong force in the nuclear medium.
Such interactions usually depend on a set of parameters fitted to
properties nuclei and infinite nuclear matter.
These interactions can suffer several limitations and problems. For
example, since they are usually adjusted on properties of observed nuclei
close to the valley of stability, their predictive power for exotic and super-heavy nuclei may be questionable. Furthermore, unphysical finite-size instabilities can sometimes appear when these interactions are used to calculate properties of nuclei which have not been considered to constrain their parameters. These unwanted features then make them of very limited interest. These instabilities can appear in various channels and therefore have scalar, vector, isoscalar or isovector characters.
It was shown that the formalism of the linear response in infinite-nuclear
matter can be used to avoid such instabilities for the construction of
zero-range interaction (of Skyrme type). Although such a formalism
was also developed for finite-range interactions (Gogny type),
the calculations for the linear response are much more time-consuming and
can hardly be incorporated in the procedure used to fit their parameters.
I will discuss how the scalar-isovector instabilities are related to the
distributions of protons and neutrons in nuclei and how, in turn,
information on charge density distributions can be used to
prevent these instabilities. Beside the avoidance of instabilities,
information about the charge distribution can lead to a better balance
between the different contributions to the binding energy of nuclei and
their evolution with mass and asymmetry. I will show that the use of
constraints on charge distributions from a set of chosen nuclei can be
used to avoid the appearance of scalar-isovector instabilities and discuss
how this could improve the predictive power of the mean-field
calculations.
