45,157 research outputs found
Remittances and inequality: a dynamic migration model
We develop a model to study the effects of migration and remittances on inequality
in the origin communities. While wealth inequality is shown to be monotonically
reduced along the time-span, the short- and the long-run impacts on income
inequality may be of opposite signs, suggesting that the dynamic relationship
between migration/remittances and inequality may well be characterized by an
inverse U-shaped pattern. This is consistent with the findings of the empirical
literature, yet offers a different interpretation from the usually assumed migration
network effects. With no need to endogenize migration costs through the role of
migration networks, we generate the same result via intergenerational wealth
accumulation
Anomalous high energy dispersion in photoemission spectra from insulating cuprates
Angle resolved photoelectron spectroscopic measurements have been performed
on an insulating cuprate Ca_2CuO_2Cl_2. High resolution data taken along the
\Gamma to (pi,pi) cut show an additional dispersive feature that merges with
the known dispersion of the lowest binding energy feature, which follows the
usual strongly renormalized dispersion of ~0.35 eV. This higher energy part
reveals a dispersion that is very close to the unrenormalized band predicted by
band theory. A transfer of spectral weight from the low energy feature to the
high energy feature is observed as the \Gamma point is approached. By comparing
with theoretical calculations the high energy feature observed here
demonstrates that the incoherent portion of the spectral function has
significant structure in momentum space due to the presence of various energy
scales.Comment: 5 pages, 3 figure
Nonperturbative signatures in pair production for general elliptic polarization fields
The momentum signatures in nonperturbative multiphoton pair production for
general elliptic polarization electric fields are investigated by employing the
real-time Dirac-Heisenberg-Wigner formalism. For a linearly polarized electric
field we find that the positions of the nodes in momenta spectra of created
pairs depend only on the electric field frequency. The polarization of external
fields could not only change the node structures or even make the nodes
disappear but also change the thresholds of pair production. The momentum
signatures associated to the node positions in which the even-number-photon
pair creation process is forbid could be used to distinguish the orbital
angular momentum of created pairs on the momenta spectra. These distinguishable
momentum signatures could be relevant for providing the output information of
created particles and also the input information of ultrashort laser pulses.Comment: 8 pages, 4 figures, submitted to Europhysics Letter
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