11,244 research outputs found
Integral relations and the adiabatic expansion method for 1+2 reactions above the breakup threshold: Helium trimers with soft-core potentials
The integral relations formalism introduced in \cite{bar09,rom11}, and
designed to describe 1+ reactions, is extended here to collision energies
above the threshold for the target breakup. These two relations are completely
general, and in this work they are used together with the adiabatic expansion
method for the description of 1+2 reactions. The neutron-deuteron breakup, for
which benchmark calculations are available, is taken as a test of the method.
The s-wave collision between the He atom and He dimer above the
breakup threshold and the possibility of using soft-core two-body potentials
plus a short-range three-body force will be investigated. Comparisons to
previous calculations for the three-body recombination and collision
dissociation rates will be shown.Comment: To be published in Physical Review
On the rise and fall of networked societies
We review recent results on the dynamics of social networks which suggest
that the interplay between the network formation process and volatility may
lead to the occurrence of discontinuous phase transitions and phase coexistence
in a large class of models. We then investigate the effects of negative links
-- links inhibiting local growth of the network -- and of a geographical
distribution of the agents in such models. We show, by extensive numerical
simulations, that both effects enhance this phenomenology, i.e. it increases
the size of the coexistence region.Comment: 6 pages, 4 figures, Proceedings of Granada Workshop 200
General integral relations for the description of scattering states using the hyperspherical adiabatic basis
In this work we investigate 1+2 reactions within the framework of the
hyperspherical adiabatic expansion method. To this aim two integral relations,
derived from the Kohn variational principle, are used. A detailed derivation of
these relations is shown. The expressions derived are general, not restricted
to relative partial waves, and with applicability in multichannel
reactions. The convergence of the -matrix in terms of the adiabatic
potentials is investigated. Together with a simple model case used as a test
for the method, we show results for the collision of a He atom on a \dimer
dimer (only the elastic channel open), and for collisions involving a Li
and two He atoms (two channels open).Comment: Accepted for publication in Physical Review
Variational description of continuum states in terms of integral relations
Two integral relations derived from the Kohn Variational Principle (KVP) are
used for describing scattering states. In usual applications the KVP requires
the explicit form of the asymptotic behavior of the scattering wave function.
This is not the case when the integral relations are applied since, due to
their short range nature, the only condition for the scattering wave function
is that it be the solution of in the internal region.
Several examples are analyzed for the computation of phase-shifts from bound
state type wave functions or, in the case of the scattering of charged
particles, it is possible to obtain phase-shifts using free asymptotic
conditions. As a final example we discuss the use of the integral relations in
the case of the Hyperspherical Adiabatic method.Comment: 34 pages, 7 figures, accepted in Phys. Rev.
Contextualizing the Cassese Report: the dictatorship that changed the United Nations human rights system and its legacy in monitoring economic, social and cultural rights
This chapter explains the key reasons underpinning the low impact of the Cassese Report on foreign aid and its relationship with human rights violations in Chile during Pinochet's dictatorship.
Through the lenses of the intergovernmental decisions establishing the mandates and scope of competences of special procedures, the analysis demonstrates the absence of political will to equate the importance granted to civil and political rights with that granted to economic, social and cultural rights. The progress to mitigate this imbalance since the time of publication of the Cassese Report has been quantitative rather than qualitative. While economic, social and cultural rights have gained prominence over the years, most advances remain insufficient, especially regarding the role of business in human rights abuses. As long as the political decisions adopted within the human rights monitoring system do not implement the indivisibility of all rights, it will be very difficult to achieve substantial progress in this field
- …