3,947 research outputs found
Higgs-otic Inflation and Moduli Stabilization
We study closed-string moduli stabilization in Higgs-otic inflation in Type
IIB orientifold backgrounds with fluxes. In this setup large-field inflation is
driven by the vacuum energy of mobile D7-branes. Imaginary selfdual (ISD)
three-form fluxes in the background source a -term and the necessary
monodromy for large field excursions while imaginary anti-selfdual (IASD)
three-form fluxes are sourced by non-perturbative contributions to the
superpotential necessary for moduli stabilization. We analyze K\"ahler moduli
stabilization and backreaction on the inflaton potential in detail. Confirming
results in the recent literature, we find that integrating out heavy K\"ahler
moduli leads to a controlled flattening of the inflaton potential. We quantify
the flux tuning necessary for stability even during large-field inflation.
Moreover, we study the backreaction of supersymmetrically stabilized complex
structure moduli and the axio-dilaton in the K\"ahler metric of the inflaton.
Contrary to previous findings, this backreaction can be pushed far out in field
space if a similar flux tuning as in the K\"ahler sector is possible. This
allows for a trans-Planckian field range large enough to support inflation.Comment: 42 pages, 10 figures, v2: comments and references added. Published
versio
The DBI Action, Higher-derivative Supergravity, and Flattening Inflaton Potentials
In string theory compactifications it is common to find an effective
Lagrangian for the scalar fields with a non-canonical kinetic term. We study
the effective action of the scalar position moduli of Type II D-branes. In
many instances the kinetic terms are in fact modified by a term proportional to
the scalar potential itself. This can be linked to the appearance of
higher-dimensional supersymmetric operators correcting the K\"ahler potential.
We identify the supersymmetric dimension-eight operators describing the
corrections captured by the D-brane Dirac-Born-Infeld action. Our
analysis then allows an embedding of the D-brane moduli effective action into
an supergravity formulation. The effects of the
potential-dependent kinetic terms may be very important if one of the scalars
is the inflaton, since they lead to a flattening of the scalar potential. We
analyze this flattening effect in detail and compute its impact on the CMB
observables for single-field inflation with monomial potentials.Comment: 25 pages, 3 figures. Comments and references added. Published versio
On the quantization of sectorially Hamiltonian dissipative systems
We present a theoretical discussion showing that, although some dissipative systems may have a sectorial Hamiltonian description, this description does not allow for canonical quantization. However, a quantum Liouville counterpart of these systems may be possible, although it may not be unique.Fil: Castagnino, Mario Alberto G. J.. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Gadella, M.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; ArgentinaFil: Lara, Luis Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; Argentin
Comportamiento electroquímico de aerogeles de carbón nanoporosos en fenómenos de desionización capacitiva
III Encuentro sobre Nanociencia y Nanotecnología de Investigadores y Tecnólogos Andaluce
A realist interpretation of quantum mechanics based on undecidability due to gravity
We summarize several recent developments suggesting that solving the problem
of time in quantum gravity leads to a solution of the measurement problem in
quantum mechanics. This approach has been informally called "the Montevideo
interpretation". In particular we discuss why definitions in this approach are
not "for all practical purposes" (fapp) and how the problem of outcomes is
resolved.Comment: 7 pages, IOPAMS style, no figures, contributed to the proceedings of
DICE 2010, Castiglioncello, slightly improved versio
Socially aware robot navigation system in human-populated and interactive environments based on an adaptive spatial density function and space affordances
Traditionally robots are mostly known by society due to the wide use of manipulators, which are generally placed in controlled environments such as factories. However, with the advances in the area of mobile robotics, they are increasingly inserted into social contexts, i.e., in the presence of people. The adoption of socially acceptable behaviours demands a trade-off between social comfort and other metrics of efficiency. For navigation tasks, for example, humans must be differentiated from other ordinary objects in the scene. In this work, we propose a novel human-aware navigation strategy built upon the use of an adaptive spatial density function that efficiently cluster groups of people according to their spatial arrangement. Space affordances are also used for defining potential activity spaces considering the objects in the scene. The proposed function defines regions where navigation is either discouraged or forbidden. To implement a socially acceptable navigation, the navigation architecture combines a probabilistic roadmap and rapidly-exploring random tree path planners, and an adaptation of the elastic band algorithm. Trials in real and simulated environments carried out demonstrate that the use of the clustering algorithm and social rules in the navigation architecture do not hinder the navigation performance
Efecto de la activación sobre la nanoporosidad de aerogeles de carbón para su uso en desionización capacitiva
Alkane coiling in perfluoroalkane solutions: a new primitive solvophobic effect
In this work, we demonstrate that n-alkanes coil when mixed with perfluoroalkanes, changing their conformational equilibria to more globular states, with a higher number of gauche conformations. The new coiling effect is here observed in fluids governed exclusively by dispersion interactions, contrary to other examples in which hydrogen bonding and polarity play important roles. FTIR spectra of liquid mixtures of n-hexane and perfluorohexane unambiguously reveal that the population of n-hexane molecules in all-trans conformation reduces from 32% in the pure n-alkane to practically zero. The spectra of peffluorohexane remain unchanged, suggesting nanosegregatiori of the hydrogenated and fluorinated chains. Molecular dynamics simulatiOns support this analysis. The new solvophobic effect is prone to have a major impact on the structure, organization, and therefore thermodynamic properties and phase equilibria of, fluids involving mixed hydrogenated and fluorinated chains.Fundacao para a Ciencia e Tecnologia [UID/NAN/50024/2013, UID/QUI/0100/2013, SFRH/BPD/81748/2011
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