Backreaction in Axion Monodromy, 4-forms and the Swampland

Axion monodromy models can always be described in terms of an axion coupled to 3-form gauge fields with non-canonical kinetic terms. The presence of the saxions parametrising the kinetic metrics of the 3-form fields leads to backreaction effects in the inflationary dynamics. We review the case in which saxions backreact on the K\"ahler metric of the inflaton leading to a logarithmic scaling of the proper field distance at large field. This behaviour is universal in Type II string flux compactifications and consistent with a refinement of the Swampland Conjecture. The critical point at which this behaviour appears depends on the mass hierarchy between the inflaton and the saxions. However, in tractable compactifications, such a hierarchy cannot be realised without leaving the regime of validity of the effective theory, disfavouring transplanckian excursions in string theory.Comment: Proceedings prepared for the "Workshop on Geometry and Physics", November 2016, Ringberg Castl

On Critical Point for Two Dimensional Holomorphics Systems

Let $f:M\rightarrow M$ be a biholomorphisms on two--dimensional a complex manifold, and let $X\subseteq M$ be a compact $f$--invariant set such that $f|X$ is asymptotically dissipative and without sinks periodic points. We introduce a solely dynamical obstruction to dominated splitting, namely critical point. Critical point is a dynamical object and capture many of the dynamical properties of their one--dimensional counterpart

Higher spin matrix models

We propose a hybrid class of theories for higher spin gravity and matrix models, i.e. which handle simultaneously higher spin gravity fields and matrix models. The construction is similar to Vasiliev's higher spin gravity but part of the equations of motion are provided by the action principle of a matrix model. In particular we construct a higher spin (gravity) matrix model related to type IIB matrix models/string theory which have a well defined classical limit, and which is compatible with higher spin gravity in $AdS$ space. As it has been suggested that higher spin gravity should be related to string theory in a high energy (tensionless) regime, and therefore to M-Theory, we expect that our construction will be useful to explore concrete connections.Comment: 13 pages, 1 table. New references and corrections from referee reports are included in this version. Current form accepted in Universe journal for the special issue on Higher Spin Gauge Theorie

Los origines de la democracia, reflexiones teóricas sobre el caso de Chile

35 p.Chile figuraba entre los países más democráticos del mundo, no sólo en los años sesenta, sino durante el último siglo y medio. Las instituciones políticas de Chile tuvieron una evolución similar a la de instituciones comparables de Europa y de los Estados Unidos, en medio de condiciones consideradas en general perjudiciales para el desarrollo de procesos y procedimientos representativos. Este artículo procura, sobre la base del caso chileno, contribuir a una explicación del origen y consolidación de los regímenes democráticos. A juicio de los autores, el caso chileno pone en tela de juicio la validez general de las teorías más aceptadas sobre la gestación de los regímenes democráticos. El artículo ofrece una interpretación histórica de la evolución de la institucionalidad chilena en comparación con otras democracias occidentales; luego señala deficiencias en las teorías culturales y económicas de los orígenes de la democracia; y, finalmente, enfatiza el valor que una aproximación histórica y política puede aportar a la gestación de una institucionalidad democrática, según se desprende del caso de Chile en el siglo XIXDisponible en http://www.cepchile.cl/1_1198/doc/los_origenes_de_la_democracia_reflexiones_teoricas_sobre_el_caso_de_chile.html#.UUB35NaZZJ

Bimetallic au/ag metal superstructures from macromolecular metal complexes in solid-state

Indexación: Web of Science; Scielo.Novel bimetallic Au/Ag superstructures have been prepared from solid-state pyrolysis of the macromolecular complexes Chitosan(MLn/M'Ln)n y PSP-4-PVPx( MLn/M'Ln)n with MLn = AuCl3 and M'Ln = Ag(CF3SO3)The characterization was made from XRD (X-ray diffraction of powder), SEM and EDS analysis. Morphologies are influenced by both the nature of the polymer and the metal/polymer, molar ratio of the polymer precursor. EDS analysis suggests a core/shell Au/Ag structure for the materials. A probable mechanism of the formation of these superstructures is discussed. Although separated reports of metallic superstructures of Au or Ag have been recently described, the here reported are the first bimetallic Au/Ag. Key words: Superstructures, Macromolecular complexes, metallic Au and Ag, Pyrolysishttp://ref.scielo.org/y6jcg