Running gravitational couplings, decoupling, and curved spacetime renormalization

We propose to slightly generalize the DeWitt-Schwinger adiabatic renormalization subtractions in curved space to include an arbitrary renormalization mass scale $\mu$. The new predicted running for the gravitational couplings are fully consistent with decoupling of heavy massive fields. This is a somewhat improvement with respect to the more standard treatment of minimal (DeWitt-Schwinger) subtractions via dimensional regularization. We also show how the vacuum metamorphosis model emerges from the running couplings.Comment: Some points clarified, misprints corrected; to appear in Phys. Rev.

Running couplings from adiabatic regularization

We extend the adiabatic regularization method by introducing an arbitrary mass scale $\mu$ in the construction of the subtraction terms. This allows us to obtain, in a very robust way, the running of the coupling constants by demanding $\mu$-invariance of the effective semiclassical (Maxwell-Einstein) equations. In particular, we get the running of the electric charge of perturbative quantum electrodynamics. Furthermore, the method brings about a renormalization of the cosmological constant and the Newtonian gravitational constant. The running obtained for these dimensionful coupling constants has new relevant (non-logarithmic) contributions, not predicted by dimensional regularization.Comment: Revised version. Some points clarified. New references added. 6 pages. To appear in Phys. Lett.

Applications of Intuitionistic Logic in Answer Set Programming

We present some applications of intermediate logics in the field of Answer Set Programming (ASP). A brief, but comprehensive introduction to the answer set semantics, intuitionistic and other intermediate logics is given. Some equivalence notions and their applications are discussed. Some results on intermediate logics are shown, and applied later to prove properties of answer sets. A characterization of answer sets for logic programs with nested expressions is provided in terms of intuitionistic provability, generalizing a recent result given by Pearce. It is known that the answer set semantics for logic programs with nested expressions may select non-minimal models. Minimal models can be very important in some applications, therefore we studied them; in particular we obtain a characterization, in terms of intuitionistic logic, of answer sets which are also minimal models. We show that the logic G3 characterizes the notion of strong equivalence between programs under the semantic induced by these models. Finally we discuss possible applications and consequences of our results. They clearly state interesting links between ASP and intermediate logics, which might bring research in these two areas together.Comment: 30 pages, Under consideration for publication in Theory and Practice of Logic Programmin

R-summed form of adiabatic expansions in curved spacetime

The Feynman propagator in curved spacetime admits an asymptotic (Schwinger-DeWitt) series expansion in derivatives of the metric. Remarkably, all terms in the series containing the Ricci scalar R can be summed exactly. We show that this (non-perturbative) property of the Schwinger-DeWitt series has a natural and equivalent counterpart in the adiabatic (Parker-Fulling) series expansion of the scalar modes in an homogeneous cosmological spacetime. The equivalence between both R-summed adiabatic expansions can be further extended when a background scalar field is also present.Comment: 13 pages. Minor changes. Misprints corrected. To appear in Phys. Rev.

Izhikevich neuron model in networks with topographical obstacles

Treballs Finals de Grau de Física, Facultat de Física, Universitat de Barcelona, Curs: 2023, Tutor: Jordi Soriano FraderaThe aim of this study is to examine the behaviour of a simulated neuronal network in which neurons are located in topographical obstacles shaped as parallel tracks that reduce the capacity of neurons to interconnect. The simulations show that three different scenarios of collective activity are observed, depending on the connectivity between neurons, from few isolated groups of neurons to the entire synchronous activation of the network. We also observed that, when neurons strongly follow the topographical pattern, the activity of the system is highly tied to the structure of the network, indicating that dynamics (functional connectivity) is highly linked to structural one

Comment on "Gravitational Pair Production and Black Hole Evaporation"

We scrutinize the recent Letter "Gravitational pair production and black hole evaporation" by M.F. Wondrak, W.D. van Suijlekom and H. Falcke [Phys. Rev. Lett. 130, 221502 (2023); arXiv:2305.18521]. We show that some consequences based on the proposed imaginary part of the lowest order effective action are in sharp tension with exact results on pair creation in electrodynamics and cosmology. This casts serious doubt on their claims for particle production in a Schwarzschild spacetime

Linear-analog transformation approach for coupled gas and power flow analysis

In this paper, we present a methodology to analyze the integrated operation of coupled natural gas and electricity networks in steady-state. The interaction of the gas network with the electrical grid is modeled through mathematical equations that represent the energy exchange between the two infrastructures. The joint natural gas and power flow is solved using the linear-analog transformation (LAT) and the Newton-Raphson (NR) algorithm, respectively. Here, a unified solution framework of the two systems is presented using the previous proposed methods. The applicability of the methodology is illustrated using two case studies: IEEE-14 bus test system combined with a 16-node natural gas network and the IEEE-30 bus test system integrated with a 15-node natural gas network with 4 compressors. The proposed methodology proves to be useful for the assessment of coupled natural gas and electricity critical infrastructures