Renormalization Group Flow of Quantum Gravity in the Einstein-Hilbert Truncation

The exact renormalization group equation for pure quantum gravity is used to derive the non-perturbative \Fbeta-functions for the dimensionless Newton constant and cosmological constant on the theory space spanned by the Einstein-Hilbert truncation. The resulting coupled differential equations are evaluated for a sharp cutoff function. The features of these flow equations are compared to those found when using a smooth cutoff. The system of equations with sharp cutoff is then solved numerically, deriving the complete renormalization group flow of the Einstein-Hilbert truncation in $d=4$. The resulting renormalization group trajectories are classified and their physical relevance is discussed. The non-trivial fixed point which, if present in the exact theory, might render Quantum Einstein Gravity nonperturbatively renormalizable is investigated for various spacetime dimensionalities.Comment: 58 pages, latex, 24 figure

Reconstruction of modified gravity with ghost dark energy models

In this work, we reconstruct the $f(R)$ modified gravity for different ghost and generalized ghost dark energy models in FRW flat universe, which describe the accelerated expansion of the universe. The equation of state of reconstructed $f(R)$ - gravity has been calculated. We show that the corresponding $f(R)$ gravity of ghost dark energy model can behave like phantom or quintessence. We also show that the equation of state of reconstructed $f(R)$ gravity for generalized ghost model can transit from quintessence regime to the phantom regime as indicated by recent observations.Comment: 13 pages, some references and one author are added. Accepted for publication by MPL

Scalar wormholes with nonminimal derivative coupling

We consider static spherically symmetric wormhole configurations in a gravitational theory of a scalar field with a potential $V(\phi)$ and nonminimal derivative coupling to the curvature describing by the term $(\epsilon g_{\mu\nu} + \kappa G_{\mu\nu}) \phi^{,\mu}\phi^{,\nu}$ in the action. We show that the flare-out conditions providing the geometry of a wormhole throat could fulfilled both if $\epsilon=-1$ (phantom scalar) and $\epsilon=+1$ (ordinary scalar). Supposing additionally a traversability, we construct numerical solutions describing traversable wormholes in the model with arbitrary $\kappa$, $\epsilon=-1$ and $V(\phi)=0$ (no potential). The traversability assumes that the wormhole possesses two asymptotically flat regions with corresponding Schwarzschild masses. We find that asymptotical masses of a wormhole with nonminimal derivative coupling could be positive and/or negative depending on $\kappa$. In particular, both masses are positive only provided $\kappa<\kappa_1\le0$, otherwise one or both wormhole masses are negative. In conclusion, we give qualitative arguments that a wormhole configuration with positive masses could be stable.Comment: 17 pages, 8 figure

Non-minimal kinetic coupling and Chaplygin gas cosmology

In the frame of the scalar field model with non minimal kinetic coupling to gravity, we study the cosmological solutions of the Chaplygin gas model of dark energy. By appropriately restricting the potential, we found the scalar field, the potential and coupling giving rise to the Chaplygin gas solution. Extensions to the generalized and modified Chaplygin gas have been made.Comment: 18 pages, 2 figures. To appear in EPJ

Observational consequences of the Standard Model Higgs inflation variants

We consider the possibility to observationally differentiate the Standard Model (SM) Higgs driven inflation with non-minimal couplingto gravity from other variants of SM Higgs inflation based on the scalar field theories with non-canonical kinetic term such as Galileon-like kinetic term and kinetic term with non-minimal derivative coupling to the Einstein tensor. In order to ensure consistent results, we study the SM Higgs inflation variants by using the same method, computing the full dynamics of the background and perturbations of the Higgs field during inflation at quantum level. Assuming that all the SM Higgs inflation variants are consistent theories, we use the MCMC technique to derive constraints on the inflationnoary parameters and the Higgs boson mass from their fit to WMAP7+SN+BAO data set. We conclude that a combination of a Higgs mass measurement by the LHC and accurate determination by the PLANCK satellite of the spectral index of curvature perturbations and tensor-to-scalar ratio will enable to distinguish among these models. We also show that the consistency relations of the SM Higgs inflation variants are distinct enough to differentiate the models.Comment: 22 pages, 4 figure

Effective Average Action in N=1 Super-Yang-Mills Theory

For N=1 Super-Yang-Mills theory we generalize the effective average action Gamma_k in a manifest supersymmetric way using the superspace formalism. The exact evolution equation for Gamma_k is derived and, introducing as an application a simple truncation, the standard one-loop beta-function of N=1 SYM theory is obtained.Comment: 17 pages, LaTeX, some remarks added, misprints corrected, to appear in Phys. Rev.

Treatment of laboratory wastes by heterogeneous photocatalysis with TiO2

La contaminación ambiental causada por la generación de desechos peligrosos es un problema creciente y globalizado. Los residuos peligrosos, una vez emitidos, pueden permanecer en el ambiente durante cientos de años. En diversos laboratorios universitarios se trabaja con distintas sustancias químicas y se efectúan una serie de operaciones que conllevan a la generación de residuos que, en la mayoría de los casos, son peligrosos para la salud y el ambiente; dentro de estos residuos están los generados en los procedimientos de la coloración de Gram.En este trabajo, se presenta una alternativa para el tratamiento de los residuos de la tinción de Gram vía Fotocatálisis Heterogénea (FH). Se utilizó TiO2 P-25 de la casa comer-cial Evonik® y como fuente de radiación una lámpara germicida; además, se usaron como técnicas de análisis la espectroscopia UV – Vis acompañada de mediciones de DQO.Dada la naturaleza de estos residuos, se determinó tratarlos en concentraciones menores a las reales (diluidas al 10 %), con dosificaciones de TiO2 según la literatura en procesos con colorantes; alcanzando en 2 horas una degradación alrededor del 70 % y una reducción de la DQO del 40 %, mostrando la viabilidad de la posible implementación de este proceso en su eliminación.Environmental pollution caused by hazardous waste is a growing and globalized prob-lem. Such waste, once emitted, can remain in the environment for hundreds of years. Chem-ical substances are handled and several operations are carried out in different university laboratories, which generates waste that in most cases is dangerous to human health and the environment. Some of these residues include those produced during Gram staining pro-cedures.This paper presents an alternative for treating residues of Gram staining by Heteroge-neous Photocatalysis (HP). Evonik® TiO2 P-25 was used, and the radiation source was a germicidal lamp. In addition, UV-Vis spectroscopy together with COD measurements were used as analytical techniques.In view of the nature of these residues, it was decided to treat them in concentrations lower than real ones (diluted to 10 %), with TiO2 dosages according to the literature on dy-ing processes. Within 2 hours, a degradation of around 70 % and a reduction of 40 % of the COD were achieved, which shows the feasibility of the implementation of this process to eliminate said wastes

Holographic superconductor models in the non-minimal derivative coupling theory

We study a general class of holographic superconductor models via the St\"{u}ckelberg mechanism in the non-minimal derivative coupling theory in which the charged scalar field is kinetically coupling to Einstein's tensor. We explore the effects of the coupling parameter on the critical temperature, the order of phase transitions and the critical exponents near the second-order phase transition point. Moreover, we compute the electric conductive using the probe approximation and check the ratios $\omega_g/T_c$ for the different coupling parameters.Comment: 12 pages, 5 figure

Interacting entropy-corrected new agegraphic tachyon, K-essence and dilaton scalar field models of dark energy in non-flat universe

We present the new agegraphic dark energy model by introducing the quantum corrections to the entropy-area relation in the setup of loop quantum gravity. Employing this new form of dark energy, we investigate the model of interacting dark energy and derive its equation of state. We study the correspondence between the tachyon, K-essence and dilaton scalar field models with the interacting entropy-corrected new agegraphic dark energy model in the non-flat FRW universe. Moreover, we reconstruct the corresponding scalar potentials which describe the dynamics of the scalar field models.Comment: 11 pages, typos fixe