4D Scenarios Research Articles

Distributional Effects of Expected Climate Mitigation Policies in Russia

Objective: The importance of assessing the socio-economic impacts of climate policies is growing as regulations are being adopted to promote decarbonization processes. Since Russia has committed to carbon neutrality by 2060, a large and diverse policy package should be launched to attain this goal. The policies need to be based on the effectiveness, equality and motivation. This paper presents the results of the first-of-a-kind research aimed to assess the impact of individual decarbonization policies on the distribution of consumer incomes and expenses for Russia. Methods: A system of simulation models was used to estimate prospective greenhouse gases (GHG) emissions pathway for Development Driven by Decarbonization and Democratization (4D scenario) and related macroeconomic effects (evolution of prices, incomes, employment and energy expenditures across major economic sectors and industries), which were used as inputs to the simulation model distributional effect of national decarbonization (DEFEND), which was specially developed to estimate the effects of climate policies at the household level split by income deciles. Results: This paper shows that only low carbon transition will sustain Russian economic growth by promoting reduced concentration of wealth and less centralized political system, whereas maintaining the extraction-based administratively ruled economic model will cause GDP to decline and form a “shagreen skin” economy. Conclusion: The paper concludes that many of the explored policies have regressive distributional effects, but sophisticated socio-economic engineering can tailor neutral climate mitigation policies to help to at least maintain the balance of income and expenses compared to the basic trajectory. This study identifies data and knowledge gaps in calibrating the models that look into the distributional effects.

Complex phase diagram and supercritical matter.

The supercritical region is often described as uniform with no definite transitions. The distinct behaviors of the matter therein, e.g., as liquidlike and gaslike, however, suggest "supercritical boundaries." Here we provide a mathematical description of these phenomena by revisiting the Yang-Lee theory and introducing a complex phase diagram, specifically a four-dimensional (4D) one with complex T and p. While the traditional 2D phase diagram with real temperature T and pressure p values (the physical plane) lacks Lee-Yang (LY) zeros beyond the critical point, preventing the occurrence of criticality, the off-plane zeros in this 4D scenario still induce critical anomalies in various physical properties. This relationship is evidenced by the correlation between the Widom line and LY edges in van der Waals, 2D Ising model, and water. The diverged supercritical boundaries manifest the high-dimensional feature of the phase diagram: e.g., when LY zeros of complex T or p are projected onto the physical plane, boundaries defined by isobaric heat capacity C_{p} or isothermal compression coefficient K_{T} emanates. These results demonstrate the incipient phase transition nature of the supercritical matter.

4D petroelastic modeling based on a presalt well

After their initial discovery in 2006, followed by an accumulated production of over 2 billion barrels of oil equivalent, the presalt carbonate reservoirs of offshore Brazil are now candidates for time-lapse seismic analysis. Therefore, we have conducted a 4D feasibility study in a Brazilian presalt reservoir well, which is composed of two types of carbonate rocks: microbialite and coquina. We evaluated two petroelastic models to obtain the acoustic impedance (AI) and shear impedance (SI) needed to estimate potential time-lapse differences ([Formula: see text], [Formula: see text], and [Formula: see text]). For this, we used the Gassmann and Xu-Payne models, in which the latter considers the pore geometry of the rock in its equations. Our analysis of both models shows that changes in pressure and saturation are very similar, and we can conclude that, despite being a carbonate, the application of Gassmann’s model is sufficient for the 4D feasibility studies conducted in the deemed reservoir because it does not require pore space geometry parameters, as does the Xu-Payne model. The analysis of the time-lapse attributes provided us with a greater comprehension of the 4D scenarios modeled, some of which presented detectability of changes in the microbialite and coquina.

Benchmarking of MANCINTAP 2.0, a parallel high-performance tool for neutron activation analysis in complex 4D scenarios

MANCINTAP is a parallel computational tool developed and maintained by Ansaldo Nucleare since 2011 to perform 4D neutron transport, activation and time-resolved dose-rate calculations in complex geometries for CPU-intensive applications. MANCINTAP creates an automated link between the 3D radiation transport code MCNP5—which is used to evaluate both the neutron fluxes for activation calculations and the resulting secondary photon dose rates—and the zero-dimensional activation code Anita2000 by handling crucial processes such as data exchange, determination of material mixtures and generation of cumulative probability distributions. Ansaldo Nucleare recently developed a new version of the tool, named MANCINTAP 2.0. A brief description of the computational tool is given here, with particular emphasis on the key technical choices underlying the project. The main enhancement is here highlighted with respect to the former version, and the results of a benchmarking campaign of MANCINTAP 2.0 against the Monte Carlo code FLUKA are described for two test cases.

Limites de las dimensiones extras considerando las leyes termodinámicas de la radiación de cuerpo negro

In this paper we will analyze the problem of blackbody radiation in an effective 4D scenario that arises from the 5D free gauge field, where the fifth dimension is compactified to a circle. The starting point is the Kaluza-Klein decomposition of the 5D gauge field action into two sectors in four dimensions: the first sector contains a massless gauge field, while the second sector yields an infinite set of massive gauge fields. Both sectors contribute to Stefan-Boltzmann’s law. By contrasting the experimental data with those obtained theoretically, a bound is obtained for the parameter associated with the scenario.

Top and bottom partners, Higgs boson on the brane, and the tth signal

Current LHC results indicate a possible enhancement in the production of Higgs bosons in association with top quarks (tth) over the Standard Model (SM) expectations, suggesting an increase in the top Yukawa coupling. To explain these results, we study the effect of adding to the SM a small set of vector-like partners of the top and bottom quarks with masses of order ~1 TeV. We consider Yukawa coupling matrices with vanishing determinant and show that then, Higgs production through gluon fusion is not affected by deviations in the top quark Yukawa coupling, and in fact depends only on deviations in the bottom quark Yukawa coupling. We call this scenario the "Brane Higgs Limit", as it can emerge naturally in models of warped extra-dimensions with all matter fields in the bulk, except the Higgs (although it could also occur in 4D scenarios with vector-like quarks and special flavor symmetries forcing the vanishing of the Yukawa determinants). We show that the scenario is highly predictive for all Higgs production/decay modes, making it easily falsifiable, maybe even at the LHC RUN 2 with higher luminosity.

Flavor universal resonances and warped gravity

Warped higher-dimensional compactifications with “bulk” standard model, or their AdS/CFT dual as the purely 4D scenario of Higgs compositeness and partial compositeness, offer an elegant approach to resolving the electroweak hierarchy problem as well as the origins of flavor structure. However, low-energy electroweak/flavor/CP constraints and the absence of non-standard physics at LHC Run 1 suggest that a “little hierarchy problem” remains, and that the new physics underlying naturalness may lie out of LHC reach. Assuming this to be the case, we show that there is a simple and natural extension of the minimal warped model in the Randall-Sundrum framework, in which matter, gauge and gravitational fields propagate modestly different degrees into the IR of the warped dimension, resulting in rich and striking consequences for the LHC (and beyond). The LHC-accessible part of the new physics is AdS/CFT dual to the mechanism of “vectorlike confinement”, with TeV-scale Kaluza-Klein excitations of the gauge and gravitational fields dual to spin-0,1,2 composites. Unlike the minimal warped model, these low-lying excitations have predominantly flavor-blind and flavor/CP-safe interactions with the standard model. Remarkably, this scenario also predicts small deviations from flavor-blindness originating from virtual effects of Higgs/top compositeness at ∼ O(10) TeV, with subdominant resonance decays into Higgs/top-rich final states, giving the LHC an early “preview” of the nature of the resolution of the hierarchy problem. Discoveries of this type at LHC Run 2 would thereby anticipate (and set a target for) even more explicit explorations of Higgs compositeness at a 100 TeV collider, or for next-generation flavor tests.

4D propagated layer-based inversion

We developed a new model-based 4D inversion algorithm that propagated through a 4D data set from a well location, minimizing the traveltime and amplitude differences of the data. The model consisted of a finite number of layers in which the thickness and change in elastic parameters were solved in each layer. The inversion used a local optimization strategy at each trace, in which the solution of a previously inverted neighboring trace was used as the initial guess; it started from a 4D layer-based inversion solution found at a well location. Information from the well was, therefore, propagated into the data set whereas it remained consistent with the data. When several wells were used simultaneously, they propagated in a concurrent manner to determine each well’s area of influence. By using the time-shift and amplitude differences, it became possible to decouple density and P-wave velocity changes; however, even with this additional information, solutions were seldom consistent enough to provide coherent quantitative interpretation. We therefore introduced a new constraint based on production information and rock physics to guide the solution to realistic combinations of elastic parameters. We determined that this constraint was fairly independent of the geology. Examples of the prestack propagation inversion algorithm were shown on synthetic and real data examples. Comparisons were also made to standard 4D inversion highlighting the improvement in the coherency of the new results. We concluded that this type of model-based inversion was not designed to be used as a reconnaissance tool for 4D interpretation (this remains the job of data-driven inversion schemes) but was a powerful tool for either extracting as much information as possible from 4D seismic data or to test various hypothesis of different 4D scenarios.

4D spacetimes embedded in 5D light-like Kasner universes

We consider spatially homogeneous, anisotropic cosmological models in 5D whose line element can be written as , where u and v are light-like coordinates. In the case where is diagonal, we construct three families of analytic solutions to the 5D vacuum field equations RAB = 0 (A, B = 0, 1, 2, 3, 4). Among them, there is a family of self-similar homothetic solutions that contains, as a particular case, the so-called light-like Kasner universes. In this work, we provide a detailed study of the different types of 4D scenarios that can be embedded in such universes. For the sake of generality of the discussion, and applicability of the results, in our analysis we consider the two versions of non-compactified 5D relativity in vogue, namely braneworld theory and induced matter theory. We find a great variety of cosmological models in 4D which are anisotropic versions of the FRW ones. We obtain models on the brane with a non-vanishing cosmological term Λ(4), which inflate à la de Sitter without satisfying the classical false-vacuum equation of state. Using the symmetry of the solutions, we construct a class of non-static vacuum solutions on the brane. We also develop static pancake-like distributions where the matter is concentrated in a thin surface (near z = 0), similar to those proposed by Zel'dovich for the shape of the first collapsed objects in an expanding anisotropic universe. The solutions discussed here can be applied in a variety of physical situations.

KALUZA–KLEIN SOLITONS RE-EXAMINED

In 4 + 1 gravity the assumption that the five-dimensional metric is independent of the fifth coordinate permits the extra dimension to be either spacelike or timelike. As a consequence of this, the time coordinate and the extra coordinate are interchangeable, which in turn allows the conception of different scenarios in 4D from a single solution in 5D. In this paper, we make a thorough investigation of all possible 4D scenarios, associated with this interchange, for the well-known Kramer–Gross–Perry–Davidson–Owen set of solutions. We show that there are three families of solutions with very distinct geometrical and physical properties. They correspond to different sets of values of the parameters which characterize the solutions in 5D. The solutions of physical interest are identified on the basis of physical requirements on the induced matter in 4D. We find that only one family satisfies these requirements; the other two violate the positivity of mass-energy density. The "physical" solutions possess a lightlike singularity which coincides with the horizon. The Schwarzschild black string solution as well as the zero moment dipole solution of Gross and Perry are obtained in different limits. These are analyzed in the context of Lake's geometrical approach. We demonstrate that the parameters of the solutions in 5D are not free, as previously considered. Instead, they are totally determined by measurements in 4D — namely, by the surface gravitational potential of the astrophysical phenomena, like the Sun or other stars, modeled in Kaluza–Klein theory. This is an important result which may help in observations for an experimental/observational test of the theory.

Modified Brans–Dicke theory of gravity from five-dimensional vacuum

We investigate, in the context of five-dimensional (5D) Brans-Dicke theory of gravity, the idea that macroscopic matter configurations can be generated from pure vacuum in five dimensions, an approach first proposed in the framework of general relativity. We show that the 5D Brans-Dicke vacuum equations when reduced to four dimensions lead to a modified version of Brans-Dicke theory in four dimensions (4D). As an application of the formalism, we obtain two five-dimensional extensions of four-dimensional O'Hanlon and Tupper vacuum solution and show that they lead two different cosmological scenarios in 4D.

Extra symmetry in the field equations in 5D with spatial spherical symmetry

We point out that the field equations in 5D, with spatial spherical symmetry, possess an extra symmetry that leaves them invariant. This symmetry corresponds to certain simultaneous interchange of coordinates and metric coefficients. As a consequence, a single solution in 5D can generate very different scenarios in 4D, ranging from static configurations to cosmological situations. A new perspective emanates from our work, namely, that different astrophysical and cosmological scenarios in 4D might correspond to the same physics in 5D. We present explicit examples that illustrate this point of view.

Flow equations in generalized braneworld scenarios

We discuss the flow equations in the context of general braneworld cosmologies with a modified Friedmann equation, for either an ordinary scalar field or a Dirac-Born-Infeld tachyon as inflaton candidates. The 4D, Randall-Sundrum, and Gauss-Bonnet cases are compared, using the patch formalism which provides a unified description of these models. The inflationary dynamics is described by a tower of flow parameters that can be evolved in time to select a particular subset of points in the space of cosmological observables. We analyze the stability of the fixed points in all the cosmologies (our results in the 4D case already extending those in the literature). Numerical integration of the flow equations shows that the predictions of the Gauss-Bonnet braneworld differ significantly as compared to the Randall-Sundrum and 4D scenarios, whereas tachyon inflation gives tensor perturbations smaller than those in the presence of a normal scalar field. These results are extended to the realization of a noncommutative space-time preserving maximal symmetry. In this case the tensor-to-scalar signal is unchanged, while blue-tilted spectra are favored.