
Acena, A., Anabalon, A., Astefanesei, D., & Mann, R. (2014). Hairy planar black holes in higher dimensions. J. High Energy Phys., (1), 21 pp.
Abstract: We construct exact hairy planar black holes in Ddimensional AdS gravity. These solutions are regular except at the singularity and have stressenergy that satisfies the null energy condition. We present a detailed analysis of their thermodynamical properties and show that the first law is satisfied. We also discuss these solutions in the context of AdS/CFT duality and construct the associated cfunction.



Agostini, C. A., Armijo, F. A., Silva, C., & Nasirov, S. (2021). The role of frequency regulation remuneration schemes in an energy matrix with high penetration of renewable energy. Renew. Energy, 171, 1097–1114.
Abstract: Renewable energies (RE) in Chile and around the world have experienced outstanding growth in recent years. However, RE technologies such as solar photovoltaic and wind generate an imbalance between generation (offer) and consumption (demand) because of their intermittent and variable nature. Moreover, RE & rsquo;s natural variability makes it necessary for conventional technologies to play a significant role in adjusting for the imbalance in the electric system frequency. As variable RE penetration grows, the need for frequency regulation will increase and, depending on how those higher costs are financed, this could lead to a disincentive to invest in conventional plants that provide that service. In this paper we study the impact of increased photovoltaic energy penetration, the leading RE in Chile, on the profitability of different conventional generation technologies. Specifically, we analyze the role that the frequency control remuneration mechanism has on that impact. For this purpose, four different solar photovoltaic penetration scenarios are simulated in Chile & rsquo;s Northern System, comparing two payment criteria for frequency regulation services: i) a costbased pricing system whose payments relate to the incurred costs and ii) a marketbased pricing system where the marginal cost of providing the services is paid. The results show that as installed photovoltaic capacity increases, the average marginal cost of energy (operation cost) decreases due to a displacement of more expensive power plants, but at the same time, investment cost may increase. In the long run, contract prices change as a result of falling operational costs and rising investment cost, resulting in changes in the profitability of all technologies. Finally, while both costbased and marketbased systems reward the ability to regulate frequency, the technologies performing the regulation receive different payments for the service, affecting both their profitability and the incentives for investment.



Agostini, C. A., Guzman, A. M., Nasirov, S., & Silva, C. (2019). A surplus based framework for crossborder electricity trade in South America. Energy Policy, 128, 673–684.
Abstract: The South American region has experienced a steady increase in its demand for electricity and faces several challenges in the development of the electricity sector. Among them, high fluctuations in hydro generation, high and volatile prices of fossil fuels, and environmental and social impacts associated to energy activities. Strengthening cooperation for crossborder electricity trade is considered a sustainable alternative for addressing these challenges. For the expansion of electricity trade among countries within the region, both infrastructure and a regulation that defines the conditions of the electric power exchanges between countries are required. A good regulatory framework would allow all market players to have access to the commercialization of energy with other countries in the region, guarantee that the treatment of exchanges is nondiscriminatory, and maintain the efficiency, cost effectiveness and security characteristics operation of all electricity systems. In this context, this paper proposes a framework with the basic setting conditions for the import and export of energy from the “surplus” available for exchange. The empirical analysis of the regulatory proposal, based on simulations, shows that the exchange of energy from Chile with its neighboring countries is feasible in a clear and transparent manner, reducing the marginal costs of energy and the total cost of operation, keeping the average cost of generation relatively constant.



Anabalon, A. (2012). Exact black holes and universality in the backreaction of nonlinear sigma models with a potential in (A)dS(4). J. High Energy Phys., (6), 18 pp.
Abstract: The aim of this paper is to construct accelerated, stationary and axisymmetric exact solutions of the Einstein theory with self interacting scalar fields in (A)dS4. To warm up, the backreaction of the (non)minimally coupled scalar field is solved, the scalar field equations are integrated and all the potentials compatible with the metric ansatz and Einstein gravity are found. With these results at hand the nonlinear sigma model is tackled. The scalar field Lagrangian is generic; neither the coupling to the curvature, neither the metric in the scalar manifold nor the potential, are fixed ab initio. The unique assumption in the analysis is the metric ansatz: it has the form of the most general Petrov type D vacuum solution of general relativity; it is a a cohomogeneity two Weyl rescaling of the Carter metric and therefore it has the typical PlebanskiDemianski form with two arbitrary functions of one variable and one arbitrary function of two variables. It is shown, by an straightforward manipulation of the field equations, that the metric is completely integrable without necessity of specifiying anything in the scalar Lagrangian. This results is that the backreaction of the scalar fields, within this class of metrics, is universal. The metric functions generically show an explicit dependence on a dynamical exponent that allows to smoothly connect this new family of solutions with the actual PlebanskiDemianski spacetime. The remaining field equations imply that the scalar fields follow geodesics in the scalar manifold with an affine parameter given by a nonlinear function of the spacetime coordinates and define the onshell form of the potential plus a functional equation that it has to satisfy. To further find the exact form of the potential the simplest case associated to a flat scalar manifold is taken. The most general potential compatible with the Einstein theory and the metric ansatz is constructed in this case and it is shown that it has less symmetry than the maximal compact subgroup of the coset construction. Finally, the most general family of (A) dS4 static hairy black holes is explicitly constructed and its properties are outlined.



Anabalon, A., Astefanesei, D., Choque, D., & Martinez, C. (2016). Trace anomaly and counterterms in designer gravity. J. High Energy Phys., (3), 29 pp.
Abstract: We construct concrete counterterms of the BalasubramanianKraus type for Einsteinscalar theories with designer gravity boundary conditions in AdS(4), so that the total action is fi nite onshell and satisfy a well de fi ned variational principle. We focus on scalar fi elds with the conformal mass m(2) = 2l(2) and show that the holographic mass matches the Hamiltonian mass for any boundary conditions. We compute the trace anomaly of the dual fi eld theory in the generic case, as well as when there exist logarithmic branches of nonlinear origin. As expected, the anomaly vanishes for the boundary conditions that are AdS invariant. When the anomaly does not vanish, the dual stress tensor describes a thermal gas with an equation of state related to the boundary conditions of the scalar fi eld. In the case of a vanishing anomaly, we recover the dual theory of a massless thermal gas. As an application of the formalism, we consider a general family of exact hairy black hole solutions that, for some particular values of the parameters in the moduli potential, contains solutions of fourdimensional gauged N = 8 supergravity and its omegadeformation. Using the AdS/CFT duality dictionary, they correspond to triple trace deformations of the dual fi eld theory.



Anabalon, A., Astefanesei, D., & Mann, R. (2013). Exact asymptotically flat charged hairy black holes with a dilaton potential. J. High Energy Phys., (10), 22 pp.
Abstract: We find broad classes of exact 4dimensional asymptotically flat black hole solutions in EinsteinMaxwell theories with a nonminimally coupled dilaton and its nontrivial potential. We consider a few interesting limits, in particular, a regular generalization of the dilatonic ReissnerNordstrom solution and, also, smooth deformations of supersymmetric black holes. Further examples are provided for more general dilaton potentials. We discuss the thermodynamical properties and show that the first law is satisfied. In the nonextremal case the entropy depends, as expected, on the asymptotic value of the dilaton. In the extremal limit, the entropy is determined purely in terms of charges and is independent of the asymptotic value of the dilaton. The attractor mechanism can be used as a criterion for the existence of the regular solutions. Since there is a 'competition' between the effective potential and dilaton potential, we also obtain regular extremal black hole solutions with just one U(1) gauge field turned on.



Anabalon, A., Astefanesei, D., & Oliva, J. (2015). Hairy black hole stability in AdS, quantum mechanics on the halfline and holography. J. High Energy Phys., (10), 15 pp.
Abstract: We consider the linear stability of 4dimensional hairy black holes with mixed boundary conditions in Antide Sitter spacetinie. We focus on the mass of scalar fields around the maximally supersymmetric vacuum of the gauged N = 8 supergravity in four dimensions, m(2) = 2l(2). It is shown that the Schrodinger operator on the halfline, governing the S2, H2 or R2 invariant mode around the hairy black hole, allows for nontrivial selfadjoint extensions and each of them corresponds to a class of mixed boundary conditions in the gravitational theory. Discarding the selfadjoint extensions with a negative mode impose a restriction on these boundary conditions. The restriction is given in terms of an integral of the potential in the Schrodinger operator resembling the estimate of Simon for Schrodinger operators on the real line. In the context of AdS/CFT duality, our result has a natural interpretation in terms of the field theory dual effective potential.



Anabalon, A., Canfora, F., Giacomini, A., & Oliva, J. (2012). Black holes with primary hair in gauged N=8 supergravity. J. High Energy Phys., (6), 12 pp.
Abstract: In this paper, we analyze the static solutions for the U(1)(4) consistent truncation of the maximally supersymmetric gauged supergravity in four dimensions. Using a new parametrization of the known solutions it is shown that for fixed charges there exist three Possible black hole configurations according to the pattern of symmetry breaking of the (scalars sector of the) Lagrangian. Namely a black hole without scalar fields, a black hole with a primary hair and a black hole with a secondary hair respectively. This is the first, exact, example of a black hole with a primary scalar hair, where both the black hole and the scalar fields are regular on and outside the horizon. The configurations with secondary and primary hair can be interpreted as a spontaneous symmetry breaking of discrete permutation and reflection symmetries of the action. It is shown that there exist a triple point in the thermodynamic phase space where the three solution coexist. The corresponding phase transitions are discussed and the free energies are written explicitly as function of the thermodynamic coordinates in the uncharged case. In the charged case the free energies of the primary hair and the hairless black hole are also given as functions of the thermodynamic coordinates.



Anabalon, A., Deruelle, N., & Julie, F. L. (2016). EinsteinKatz action,variational principle, Noether charges and the thermodynamics of AdSblack holes. J. High Energy Phys., (8), 15 pp.
Abstract: In this paper we describe 4dimensional gravity coupled to scalar and Maxwell fields by the EinsteinKatz action, that is, the covariant version of the “GammaGamma – GammaGamma” part of the Hilbert action supplemented by the divergence of a generalized “Katz vector”. We consider static solutions of Einstein's equations, parametrized by some integration constants, which describe an ensemble of asymptotically AdS black holes. Instead of the usual Dirichlet boundary conditions, which aim at singling out a specific solution within the ensemble, we impose that the variation of the action vanishes on shell for the broadest possible class of solutions. We will see that, when a longrange scalar “hair” is present, only subfamilies of the solutions can obey that criterion. The KatzBicakLyndenBell (“KBL”) superpotential built on this (generalized) vector will then give straightforwardly the Noether charges associated with the spacetime symmetries (that is, in the static case, the mass). Computing the action on shell, we will see next that the solutions which obey the imposed variational principle, and with Noether charges given by the KBL superpotential, satisfy the Gibbs relation, the Katz vectors playing the role of “counterterms”. Finally, we show on the specific example of dyonic black holes that the subclass selected by our variational principle satisfies the first law of thermodynamics when their mass is de fined by the KBL superpotential.



Barroso, L., Munoz, F. D., Bezerra, B., Rudnick, H., & Cunha, G. (2021). ZeroMarginalCost Electricity Market Designs: Lessons Learned From Hydro Systems in Latin America Might Be Applicable for Decarbonization. IEEE Power Energy Mag., 19(1), 64–73.
Abstract: Large reductions in the cost of renewable energy technologies, particularly wind and solar, as well as various instruments used to achieve decarbonization targets (e.g., renewable mandates, renewable auctions, subsidies, and carbon pricing mechanisms) are driving the rapid growth of investments in these generation technologies worldwide.



Bergen, M., & Munoz, F. D. (2018). Quantifying the effects of uncertain climate and environmental policies on investments and carbon emissions: A case study of Chile. Energy Econ., 75, 261–273.
Abstract: In this article we quantify the effect of uncertainty of climate and environmental policies on transmission and generation investments, as well as on CO2 emissions in Chile. We use a twostage stochastic planning model with recourse or corrective investment options to find optimal portfolios of infrastructure both under perfect information and uncertainty. Under a series of assumptions, this model is equivalent to the equilibrium of a much more complicated bilevel market model, where a transmission planner chooses investments first and generation firms invest afterwards. We find that optimal investment strategies present important differences depending on the policy scenario. By changing our assumption of how agents will react to this uncertainty we compute bounds on the cost that this uncertainty imposes on the system, which we estimate ranges between 3.2% and 5.7% of the minimum expected system cost of $57.6B depending on whether agents will consider or not uncertainty when choosing investments. We also find that, if agents choose investments using a stochastic planning model, uncertain climate policies can result in nearly 18% more CO2 emissions than the equilibrium levels observed under perfect information. Our results highlight the importance of credible and stable longterm regulations for investors in the electric power industry if the goal is to achieve climate and environmental targets in the most costeffective manner and to minimize the risk of asset stranding. (C) 2018 Elsevier B.V. All rights reserved.



Berkovits, N., & Chandia, O. (2014). Simplified pure spinor b ghost in a curved heterotic superstring background. J. High Energy Phys., (6), 12 pp.
Abstract: Using the RNSlike fermionic vector variables introduced in arXiv:1305.0693, the pure spinor b ghost in a curved heterotic superstring background is easily constructed. This construction simplifies and completes the b ghost construction in a curved background of arXiv:1311.7012.



Brems, A., Caceres, G., Dewil, R., Baeyens, J., & Pitie, E. (2013). Heat transfer to the riserwall of a circulating fluidised bed (CFB). Energy, 50, 493–500.
Abstract: The circulating fluidized bed is of increasing importance for gassolid and gascatalytic reactions, for drying, and recently its use in solar energy capture and storage has been advocated. In all applications, the supply or withdrawal of heat is a major issue, and the heat transfer coefficient from the gassolid suspension to the heat transfer surface needs to be determined as design parameter. The present paper investigates the heat transfer coefficient for different operating gas velocity and solids circulation flux, whilst covering the different hydrodynamic solid flow regimes of dilute, coreannulus or dense mode. Measured values of the walltobed heat transfer coefficients are compared with empirical predictions of both Molodstof and Muzyka, and Golriz and Grace. The application of a packet renewal mechanism at the wall is also investigated, and introducing the predicted solid contact time at the wall provides a very fair estimate of the heat transfer coefficient. Crown Copyright (C) 2012 Published by Elsevier Ltd. All rights reserved.



Caceres, G., Anrique, N., Girard, A., Degreve, J., Baeyens, J., & Zhang, H. L. (2013). Performance of molten salt solar power towers in Chile. J. Renew. Sustain. Energy, 5(5), 15 pp.
Abstract: Chile is facing important challenges to develop its energy sector. Estimations demonstrate that in its electricity consumption Chile will grow at an annual rate of 4.6% until 2030, despite ongoing efficiency improvements. To satisfy this demand in a sustainable way, the national energy policy promotes the integration of novel and clean power generation into the national power mix, with special emphasis on concentrated solar power (CSP). The present paper assesses the development of solarbased electricity generation in Chile by CSP, achieved by a Solar Power Tower plant (SPT) using molten salt as heat carrier and store. Such SPTs can be installed at different locations in Chile, and connected to the main national grid. Results show that each SPT plant can generate around 76 GWh(el) of net electricity, when considering solar irradiation as the sole energy source and at a 16% overall efficiency of the SPT process. For operation in a continuous mode, a hybrid configuration with integrated gas backup system increases the generating potential of each SPT to 135 GWh(el). A preliminary Levelized Energy Cost (LEC) calculation provides LEC values between 0.15 and 0.18 $/kWh, as function of the overall process efficiency and estimated investment cost. Chile's solar irradiation favors the implementation of SPT plants. (C) 2013 AIP Publishing LLC.



Canfora, F., Gomberoff, A., Oh, S. H., Rojas, F., & SalgadoRebolledo, P. (2019). Meronic EinsteinYangMills black hole in 5D and gravitational spin from isospin effect. J. High Energy Phys., (6), 32 pp.
Abstract: We construct an analytic black hole solution in SU(2) EinsteinYangMills theory in five dimensions supporting a Meron field. The gauge field is proportional to a pure gauge and has a nontrivial topological charge. The wouldbe singularity at the Meron core gets shielded from the exterior by the black hole horizon. The metric has only one integration constant, namely, its ADM mass, which is shown to be finite once an appropriate boundary term is added to the action. The thermodynamics is also worked out, and a firstorder phase transition, similar to the one occurring in the ReissnerNordstrom case is identified. We also show that the solution produces a spin from isospin effect, i.e., even though the theory is constructed out of bosons only, the combined system of a scalar field and this background may become fermionic. More specifically, we study scalar excitations in this purely bosonic background and find that the system describes fermionic degrees of freedom at spatial infinity. Finally, for the asymptotically AdS(5) case, we study its consequences in the context of the AdS/CFT correspondence.



Chandia, O. (2014). The nonminimal heterotic pure spinor string in a curved background. J. High Energy Phys., (3), 16 pp.
Abstract: We study the nonminimal pure spinor string in a curved background. We find that the minimal BRST invariance implies the existence of a nontrivial stressenergy tensor for the minimal and nonminimal variables in the heterotic curved background. We find constraint equations for the b ghost. We construct the b ghost as a solution of these constraints.



Chandia, O., & Vallilo, B. C. (2015). C Ambitwistor pure spinor string in a type II supergravity background. J. High Energy Phys., (6), 15 pp.
Abstract: We construct the ambitwistor pure spinor string in a general type II supergravity background in the semiclassical regime. Almost all supergravity constraints are obtained from nilpotency of the BRST charge and further consistency conditions from additional worldsheet the case of AdS(5) x S (5) background.



Chandia, O., & Vallilo, B. C. (2015). Nonminimal fields of the pure spinor string in general curved backgrounds. J. High Energy Phys., (2), 16 pp.
Abstract: We study the coupling of the nonminimal ghost fields of the pure spinor superstring in general curved backgrounds. The coupling is found solving the consistency relations from the nilpotency of the nonminimal BRST charge.



Chandia, O., Bevilaqua, L. I., & Vallilo, B. C. (2014). AdS pure spinor superstring in constant backgrounds. J. High Energy Phys., (6), 16 pp.
Abstract: In this paper we study the pure spinor formulation of the superstring in AdS(5) x S5 around point particle solutions of the classical equations of motion. As a particular example we quantize the pure spinor string in the BMN background.



Chandia, O., Linch, W. D., & Vallilo, B. C. (2011). Compactification of the heterotic pure spinor superstring II. J. High Energy Phys., (10), 22 pp.
Abstract: We study compactifications of the heterotic pure spinor superstring to six and four dimensions focusing on two simple CalabiYau orbifolds. We show that the correct spectrum can be reproduced only if, in the twisted sector, there remain exactly 5 and 2 pure spinor components untwisted, respectively. This naturally defines a “small” Hilbert space of untwisted variables. We point out that the cohomology of the reduced differential on this small Hilbert space can be used to describe the states in the untwisted sector, provided certain auxiliary constraints are defined. In dimension six, the mismatch between the number of pure spinor components in the small Hilbert space and the number of components of a sixdimensional pure spinor is interpreted as providing the projective measure on the analytic subspace (in the projective description) of harmonic superspace.

