Complexity is Simple

In this note we investigate the role of Lloyd's computational bound in holographic complexity. Our goal is to translate the assumptions behind Lloyd's proof into the bulk language. In particular, we discuss the distinction between orthogonalizing and `simple' gates and argue that these notions are useful for diagnosing holographic complexity. We show that large black holes constructed from series circuits necessarily employ simple gates, and thus do not satisfy Lloyd's assumptions. We also estimate the degree of parallel processing required in this case for elementary gates to orthogonalize. Finally, we show that for small black holes at fixed chemical potential, the orthogonalization condition is satisfied near the phase transition, supporting a possible argument for the Weak Gravity Conjecture first advocated in Brown et al

The Weak Gravity Conjecture in three dimensions

We study weakly coupled $U(1)$ theories in $AdS_3$, their associated charged BTZ solutions, and their charged spectra. We find that modular invariance of the holographic dual two-dimensional CFT and compactness of the gauge group together imply the existence of charged operators with conformal dimension significantly below the black hole threshold. We regard this as a form of the Weak Gravity Conjecture (WGC) in three dimensions. We also explore the constraints posed by modular invariance on a particular discrete $\mathbb{Z}_N$ symmetry which arises in our discussion. In this case, modular invariance does not guarantee the existence of light $\mathbb{Z}_N$-charged states. We also highlight the differences between our discussion and the usual heuristic arguments for the WGC based on black hole remnants.Comment: 44 page

A Chern-Simons Pandemic

In this paper we study the consistency of generalized global symmetries in theories of quantum gravity, in particular string theory. Such global symmetries arise in theories with $(p+1)$-form gauge fields, and for spacetime dimension $d\leq p+3$ there are obstructions to their breaking even by quantum effects of charged objects. In 4d theories with a 2-form gauge field (or with an axion scalar), these fields endow Schwarzschild black holes with quantum hair, a global charge leading to usual trouble with remnants. We describe precise mechanisms, and examples from string compactifications and holographic pairs, in which these problems are evaded by either gauging or breaking the global symmetry, via (suitable versions of) Stuckelberg or Kaloper-Sorbo couplings. We argue that even in the absence of such couplings, the generic solution in string theory is the breaking of the global symmetries by cubic Chern-Simons terms involving different antisymmetric tensor fields. We conjecture that any theory with (standard or higher-degree antisymmetric tensor) gauge fields is in the Swampland unless its effective action includes such Chern-Simons terms. This conjecture implies that many familiar theories, like QED (even including the charged particles required by the Weak Gravity Conjecture) or $\mathcal{N}=8$ supergravity in four dimensions, are inconsistent in quantum gravity unless they are completed by these Chern-Simons terms.Comment: 60 pages, 2 figure

Relaxion Monodromy and the Weak Gravity Conjecture

The recently proposed relaxion models require extremely large trans-Planckian axion excursions as well as a potential explicitly violating the axion shift symmetry. The latter property is however inconsistent with the axion periodicity, which corresponds to a gauged discrete shift symmetry. A way to make things consistent is to use monodromy, i.e. both the axion and the potential parameters transform under the discrete shift symmetry. The structure is better described in terms of a 3-form field $C_{\mu \nu \rho}$ coupling to the SM Higgs through its field strength $F_4$. The 4-form also couples linearly to the relaxion, in the Kaloper-Sorbo fashion. The extremely small relaxion-Higgs coupling arises in a see-saw fashion as $g\simeq F_4/f$, with $f$ being the axion decay constant. We discuss constraints on this type of constructions from membrane nucleation and the Weak Gravity Conjecture. The latter requires the existence of membranes, whose too fast nucleation could in principle drive the theory out of control, unless the cut-off scale is lowered. This allows to constrain relaxion models on purely theoretical grounds. We also discuss possible avenues to embed this structure into string theory.Comment: 26 pages + appendices, 3 figures; v3: Corrected bounds on relaxion parameter spac

Anti-Crime Programs: An Evaluation of the Comuna Segura Program

The aim of this paper is to evaluate the impact that the anti-crime program Comuna Segura: Compromiso 100 had on the reporting rate of different types of crimes. This program, implemented in Chile starting in 2001, was very highly criticized and, therefore, was eliminated in 2006. This paper provides statistical evidence, using the impact assessment methodology, which shows that the program was successful in increasing the reporting rate in targeted municipalities and also in decreasing levels of crimes associated with other crimes, such as rape. All this underlies the importance of carrying out formal impact assessments in order to determine benefits that are associated with a particular program. However, financial issues are also very important too and it is necessary to take them in account when making a fair statement about the cost-effectiveness of the program. This point is, however, not addressed in this paper but should be kept in mind in order to have a complete picture of the program.Crime, Program evaluation, Matching.

Biorremediación de suelos contaminados con Cr (VI) y lindano

Retirado 17-10-2019 a solicitud del autor[EN] Nowadays mixed pollution affects more than one third of the polluted soils in the world, therefore is needed to study harmless tecniques for the enviroment capable of doing an efficient management of the resources of a contaminated, degraded and depleted soil, and revalue it by its descontamination, soil health recuperation and revegetation. These actions generate vegetal biomass that can be use to make biofuel, reducing the costs. Chrome has two states of valencia, being Cr (VI) the most toxic for the organisms. Lindane is an organic pesticide widely used for decades that is harmful to humans and environment. This study aims to use different biorremediation technologies to reduce Cr (VI) and lindane bioavailability in soil, and to improve polluted soil health status. Soil was collected around industrial zone of Jundiz (Vitoria). Soil samples were polluted with two known concentrations of the contaminants (control, 100 ppm Cr (VI) + 10 ppm lindane, and 300 ppm Cr(VI) + 10 ppm lindane), and to half of the samples was added an organic amendment. Contaminants stabilized for one month in the soil and then were applied the biologic treatments (a bacteria consortium isolated from a polluted soil with Cr (VI) and lindane, and plant especies, Brassica napus). Soil bioestimulation with organic matter was very effective in decreasing Cr (VI), reducing its toxicity and improving microbial activity and biomass, bioindicators of soil health. Inoculation of bacterian consortium (bioaugmentation) and presence of plants had positive effects in Cr (VI) and lindane reduction, while plant presence improved microorganism biodiversity of soils. Joint action of bioestimulation, bioaugmentation anf phytoremediation was the most effective way to reduce contaminant bioavailability and to improve soil health.[ES] La contaminación mixta afecta actualmente a más de un tercio de los suelos contaminados del planeta, por eso, es necesario estudiar técnicas respetuosas con el medio ambiente capaces de realizar una gestión eficiente de los recursos de un suelo contaminado, degradado y empobrecido, y revalorizarlo mediante su descontaminación, recuperación de la salud del suelo y revegetación. Todo este proceso genera biomasa vegetal que puede ser aprovechada para generar biocombustible, reduciendo el coste del proceso. El cromo posee dos estados de valencia, siendo el Cr(VI) el más tóxico para todos los organismos. El lindano es un pesticida orgánico ampliamente usado durante décadas perjudicial para los seres humanos y el medio ambiente. En este trabajo se pretende utilizar diferentes tecnologías de biorremediación para reducir en un suelo con contaminación mixta la biodisponibilidad del Cr (VI) y del lindano, así como mejorar el estado de salud del suelo contaminado. Para ellos se contaminó un suelo empobrecido recogido en los alrededores de la zona industrial de Jundiz (Vitoria). Las muestras de suelo fueron contaminadas con dos concentraciones conocidas de los contaminantes (control, 100 ppm Cr (VI) + 10 ppm lindano y 300 ppm de Cr (VI) + 10 ppm de lindano) y a la mitad de ellos se le añadió enmienda orgánica. Se dejaron estabilizar los contaminantes en el suelo y después se aplicaron los tratamientos biológicos (un consorcio bacteriano aislado de un suelo contaminado con Cr (VI) y lindano, y plantas de la especie Brassica napus). La bioestimulación con materia orgánica de los suelos resultó ser muy eficaz para disminuir la biodisponibilidad del Cr (VI), reduciendo su toxicidad, y mejorando la actividad y biomasa microbianas, bioindicadores de la salud del suelo. La inoculación del consorcio bacteriano (biaoumentación) tuvo efectos positivos en la reducción del Cr(VI) y del lindano, mientras que la presencia de plantas mejoró la biodiversidad de microorganismos del suelo. La acción conjunta de las tecnologías de bioestimulación, biaumentación y fitorremediación fue la forma más eficaz de reducir la biodisponibilidad de los contaminantes y de mejorar la salud del suelo

A Market-Based Environmental Policy Experiment in Chile

Despite the increasing interest in the use of emissions trading for pollution control, empirical evidence reduces to a few experiences in the US. This paper studies the “"emission-offsets trading program”" established since 1992 to control particulate in Santiago-Chile. While the program is doing well from an environmental perspective, thanks, in part, to the price-based introduction of natural gas, the market is poorly performing because of high transaction costs, uncertainty and low enforcement. However, the scarcity rents created by the allocation of grandfathered emission rights to incumbents have proved very effective for the completion of the emissions inventory.