2,806 research outputs found
Relativistic symmetry breaking in light kaonic nuclei
As the experimental data from kaonic atoms and scatterings imply
that the -nucleon interaction is strongly attractive at saturation
density, there is a possibility to form -nuclear bound states or kaonic
nuclei. In this work, we investigate the ground-state properties of the light
kaonic nuclei with the relativistic mean field theory. It is found that the
strong attraction between and nucleons reshapes the scalar and vector
meson fields, leading to the remarkable enhancement of the nuclear density in
the interior of light kaonic nuclei and the manifest shift of the
single-nucleon energy spectra and magic numbers therein. As a consequence, the
pseudospin symmetry is shown to be violated together with enlarged spin-orbit
splittings in these kaonic nuclei.Comment: 15 pages, 7 figure
An interpretable machine-learned model for international oil trade network
Energy security and energy trade are the cornerstones of global economic and
social development. The structural robustness of the international oil trade
network (iOTN) plays an important role in the global economy. We integrate the
machine learning optimization algorithm, game theory, and utility theory for
learning an oil trade decision-making model which contains the benefit
endowment and cost endowment of economies in international oil trades. We have
reconstructed the network degree, clustering coefficient, and closeness of the
iOTN well to verify the effectiveness of the model. In the end, policy
simulations based on game theory and agent-based model are carried out in a
more realistic environment. We find that the export-oriented economies are more
vulnerable to be affected than import-oriented economies after receiving
external shocks. Moreover, the impact of the increase and decrease of trade
friction costs on the international oil trade is asymmetrical and there are
significant differences between international organizations.Comment: 14 pages, 5 figure
Strong correlation of the neutron star core-crust transition density with the -meson mass via vacuum polarization
We study the neutron star core-crust transition density with the
inclusion of the vacuum polarization in the dielectric function in the
nonlinear relativistic Hartree approach (RHAn). It is found that the strong
correlation between the and the scalar meson mass
strikingly overwhelms the uncertainty of the nuclear equation of state in the
RHAn models, in contrast to the usual awareness that is
predominantly sensitive to the isovector nuclear potential and symmetry energy.
The accurate extraction of through the future gravitational wave
measurements can thus provide a strong constraint on the longstanding
uncertainty of , which is of significance to better infer the
vacuum property. As an astrophysical implication, it suggests that the
correlation between and is very favorable to reconcile the
difficulty in reproducing the large crustal moment of inertia for the pulsar
glitches with the well constrained symmetry energy.Comment: 11 pages, 4 figure
Should gold be stored in chaotic eras?
This article explores the necessity to store gold in chaotic eras
from the perspective of geopolitical risk (G.P.R.). We examine the
casual relationship between G.P.R. and gold price (G.P.) by applying
the full- and sub-sample rolling-window bootstrap causality
test. The positive effect from G.P.R. to G.P. reveals that gold
should be stored in chaotic eras, due to its rising price during
high risks of geopolitics. However, the negative effect does not
confirm this view, G.P. may decrease during certain high G.P.R.
periods, which are not necessary to store gold. G.P. may also
increase during periods of low G.P.R., in order to hedge risks of
economic crises, rather than geopolitical events. These results are
inconsistent with the capital asset pricing model, which highlights
a positive effect from G.P.R. to G.P. In turn, the positive influence
of G.P. on G.P.R. points out that the gold market can be an effective
predictor of the risks of geopolitics. In the context of an
unstable pattern of global politics, investors and governments
can benefit from the gold value in the chaotic eras to avoid losses
and optimize investment. In turn, they can accurately predict
G.P.R. based on G.P., in order to prevent G.P.R.s
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