1,999 research outputs found
Exact Bethe Ansatz solution for chains with non- invariant open boundary conditions
The Nested Bethe Ansatz is generalized to open and independent boundary
conditions depending on two continuous and two discrete free parameters. This
is used to find the exact eigenvectors and eigenvalues of the vertex
models and spin chains with such boundary conditions. The solution is
found for all diagonal families of solutions to the reflection equations in all
possible combinations. The Bethe ansatz equations are used to find de first
order finite size correction.Comment: Two references adde
El control de la inmigración irregular en España: compromisos y desarrollos
Esta contribución realiza un examen crítico de los desarrollos más recientes producidos en la práctica española en relación con el control de la inmigración irregular. Se analizan tanto los compromisos gestados en el marco del proceso de integración europea y sus implicaciones relacionadas con el control de las fronteras exteriores, como los desarrollos convencionales y «paraconvencionales» (acuerdos no normativos, memorandos de entendimiento, etc.) concluidos por España y orientados al control de los flujos de personas. En este orden, el examen incide igualmente en las obligaciones internacionales de España en materia de derechos humanos y aborda finalmente los desarrollos internos más recientes, tanto las modificaciones legislativas aprobadas o en curso como la práctica administrativa. Asimismo, se valora críticamente la congruencia de este conjunto de desarrollos y se analizan episodios como las «devoluciones en caliente», abordados a la luz de los parámetros precedentes
Exact solution of the invariant quantum spin chains
The Nested Bethe Ansatz is generalized to open boundary conditions. This is
used to find the exact eigenvectors and eigenvalues of the vertex
model with fixed open boundary conditions and the corresponding
invariant hamiltonian.
The Bethe Ansatz equations obtained are solved in the thermodynamic limit
giving the vertex model free energy and the hamiltonian ground state energy
including the corresponding boundary contributions.Comment: 29 page
Colmando los espacios de "no derecho" en el Convenio Europeo de Derechos Humanos? Su eficacia extraterritorial a la luz de la Jurisprudencia
La destrucción de dos plataformas iraníes por EE.UU. ¿un nuevo supuesto de represalia armada lícita?
The estación de las Delicias site (Madrid) and paleolithic research in the Manzanares valley
El yacimiento madrileño de las Delicias, excavado por Obermaier y Wernert en 1918, ha sido
durante décadas uno de los más notables del conjunto de localidades paleolíticas clásicas del
valle del Manzanares. En el presente artículo se hace un repaso crítico de la documentación
ofrecida por la antigua excavación, se evalúan historiográficamentelas distintasinterpretaciones
vertidas sobre la industria del yacimiento y se enumeran algunos de los objetivos sobre los
que construir un nuevo proyecto de excavación sobrelos depósitos aún conservados del mismo.The archaeological site of Las Delicias (Madrid) excavated by Obermaier andWernert in 1918,
it has been one of the most important classic palaeolithic sites of the Manzanares valley for
years. In this paper we offer a critical review of all the data caming from ancient excavation,
together with an historiographical evaluation of the different interpretations based on lithic
industry of the site, and finally we want to set some objectives looking for a new archaeological
research in the Delicia´s remaining sediment
Integrable open-boundary conditions for the supersymmetric t-J model. The quantum group invariant case
We consider integrable open--boundary conditions for the supersymmetric t--J
model commuting with the number operator and . Four families, each
one depending on two arbitrary parameters, are found. We find the relation
between Sklyanin's method of constructing open boundary conditions and the one
for the quantum group invariant case based on Markov traces. The eigenvalue
problem is solved for the new cases by generalizing the Nested Algebraic Bethe
ansatz of the quantum group invariant case (which is obtained as a special
limit). For the quantum group invariant case the Bethe ansatz states are shown
to be highest weights of .Comment: Latex, 24 pages. Some new comments and references. Final version to
appear in Nucl. Phys.
Globular Clusters: DNA of Early-Type galaxies?
This paper explores if the mean properties of Early-Type Galaxies (ETG) can
be reconstructed from "genetic" information stored in their GCs (i.e., in their
chemical abundances, spatial distributions and ages). This approach implies
that the formation of each globular occurs in very massive stellar
environments, as suggested by some models that aim at explaining the presence
of multi-populations in these systems. The assumption that the relative number
of globular clusters to diffuse stellar mass depends exponentially on chemical
abundance, [Z/H], and the presence of two dominant GC sub-populations blue and
red, allows the mapping of low metallicity halos and of higher metallicity (and
more heterogeneous) bulges. In particular, the masses of the low-metallicity
halos seem to scale up with dark matter mass through a constant. We also find a
dependence of the globular cluster formation efficiency with the mean projected
stellar mass density of the galaxies within their effective radii. The analysis
is based on a selected sub-sample of galaxies observed within the ACS Virgo
Cluster Survey of the {\it Hubble Space Telescope}. These systems were grouped,
according to their absolute magnitudes, in order to define composite fiducial
galaxies and look for a quantitative connection with their (also composite)
globular clusters systems. The results strengthen the idea that globular
clusters are good quantitative tracers of both baryonic and dark matter in
ETGs.Comment: 20 pages, 28 figures and 5 table
El marco jurídico internacional y europeo de acogida de los refugiados y la incidencia de la declaración UE-Turquía.
Curso de Verano 2016 : 14 y 15 de julio de 2016 Palacio Miramar, Donostia-San Sebastián.
XV Premio Investigación Francisco Javier de Landaburu Universitas 2016
Circular strings, wormholes and minimum size
The quantization of circular strings in an anti-de Sitter background
spacetime is performed, obtaining a discrete spectrum for the string mass. A
comparison with a four-dimensional homogeneous and isotropic spacetime coupled
to a conformal scalar field shows that the string radius and the scale factor
have the same classical solutions and that the quantum theories of these two
models are formally equivalent. However, the physically relevant observables of
these two systems have different spectra, although they are related to each
other by a specific one-to-one transformation. We finally obtain a discrete
spectrum for the spacetime size of both systems, which presents a nonvanishing
lower bound.Comment: 11 pages, LaTeX2e, minor change
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