10,132 research outputs found
Nuclear response functions with finite range Gogny force: tensor terms and instabilities
A fully-antisymmetrized random phase approximation calculation employing the
continued fraction technique is performed to study nuclear matter response
functions with the finite range Gogny force. The most commonly used parameter
sets of this force, as well as some recent generalizations that include the
tensor terms are considered and the corresponding response functions are shown.
The calculations are performed at the first and second order in the continued
fraction expansion and the explicit expressions for the second order tensor
contributions are given. Comparison between first and second order continued
fraction expansion results are provided. The differences between the responses
obtained at the two orders turn to be more pronounced for the forces including
tensor terms than for the standard Gogny ones. In the vector channels the
responses calculated with Gogny forces including tensor terms are characterized
by a large heterogeneity, reflecting the different choices for the tensor part
of the interaction. For sake of comparison the response functions obtained
considering a G-matrix based nuclear interaction are also shown. As first
application of the present calculation, the possible existence of spurious
finite-size instabilities of the Gogny forces with or without tensor terms has
been investigated. The positive conclusion is that all the Gogny forces, but
the GT2 one, are free of spurious finite-size instabilities. In perspective,
the tool developed in the present paper can be inserted in the fitting
procedure to construct new Gogny-type forces
Heavy flavours in heavy-ion collisions: quenching, flow and correlations
We present results for the quenching, elliptic flow and azimuthal
correlations of heavy flavour particles in high-energy nucleus-nucleus
collisions obtained through the POWLANG transport setup, developed in the past
to study the propagation of heavy quarks in the Quark-Gluon Plasma and here
extended to include a modeling of their hadronization in the presence of a
medium. Hadronization is described as occurring via the fragmentation of
strings with endpoints given by the heavy (anti-)quark Q(Qbar) and a thermal
parton qbar(q) from the medium. The flow of the light quarks is shown to affect
significantly the R_AA and v_2 of the final D mesons, leading to a better
agreement with the experimental data. The approach allows also predictions for
the angular correlation between heavy-flavour hadrons (or their decay
electrons) and the charged particles produced in the fragmentation of the
heavy-quark strings
Neutron electromagnetic form factors and inclusive scattering of polarized electrons by polarized He and H targets
The electromagnetic inclusive responses of polarized He and H are
thoroughly investigated at the quasielastic peak for squared momentum transfers
up to , within the plane wave impulse approximation. Great
emphasys is put on the effects in the bound-state due to different two- and
three-body nuclear forces, and to the Coulomb interaction as well. A careful
analysis of the polarized responses allows to select possible experiments for
minimizing the model dependence in the extraction of the neutron
electromagnetic form factors. In particular, the relevant role played by the
proton in the transverse-longitudinal response of polarized He, at low
momentum transfer, can be utilized for obtaining valuable information on the
proton contribution to the total polarized response and eventually on the
neutron charge form factor.Comment: 27 pages, Latex, 9 Postscript figures. To appear in Phys. Rev. C
(July '97
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