Ghilencea, D. M.
Published in
The European Physical Journal C

We present a comparative study of inflation in two theories of quadratic gravity with gauged scale symmetry: (1) the original Weyl quadratic gravity and (2) the theory defined by a similar action but in the Palatini approach obtained by replacing the Weyl connection by its Palatini counterpart. These theories have different vectorial non-metricity ...

Wollensak, Matthias
Published in
The European Physical Journal C

Based upon the exact formal solutions of the Weyl–Dirac-equation in anisotropic planar Bianchi-type-I background spacetimes with power law scale factors, one can introduce suitable equivalence classes of the solutions of these models. The associated background spacetimes are characterized by two parameters. It is shown that the exact solutions of a...

Wang, Mingzhi Chen, Songbai Jing, Jiliang
Published in
The European Physical Journal C

We have studied the shadows of a Schwarzschild black hole under a special polar gravitational perturbation, which is a particular solution of Einstein equations expanded up to first order. It is shown that the black hole shadow changes periodically with time and the change of shadow depends on the Legendre polynomial order parameter l and the frequ...

Kim, Jin Young
Published in
The European Physical Journal C

We study the propagation of light under a strong electric field in Born–Infeld electrodynamics. The nonlinear effect can be described by the effective indices of refraction. Because the effective indices of refraction depend on the background electric field, the path of light can be bent when the background field is non-uniform. We compute the bend...

Hohmann, Manuel
Published in
The European Physical Journal C

We present a package for the computer algebra system Mathematica, which implements the parametrized post-Newtonian (PPN) formalism. This package, named xPPN, is built upon the widely used tensor algebra package suite xAct, and in particular the package xTensor therein. The main feature of xPPN is to provide functions to perform a proper 3+1\documen...

Kanzi, Sara Sakallı, İzzet
Published in
The European Physical Journal C

In the framework of the Lorentz symmetry breaking (LSB), we investigate the quasinormal modes (QNMs) and the greybody factors (GFs) of the Kerr-like black hole spacetime obtained from the bumblebee gravity model. In particular, we analyze the scalar and fermionic perturbations of the black hole within the framework of both semi-analytic WKB method ...

Agostini, M. Araujo, G. Bakalyarov, A. M. Balata, M. Barabanov, I. Baudis, L. Bauer, C. Bellotti, E. Belogurov, S. Bettini, A.
...
Published in
The European Physical Journal C

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Hayasaka, K. Huang, Z. Kou, E.
Published in
The European Physical Journal C

We propose to measure the τ-→K1-ντ→(K-ω)ντ→(K-π+π-π0)ντ\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\tau ^-\rightarrow K_1^-\nu _\tau \rightarrow (K^-\omega ) \nu _\...

Giovannini, Massimo
Published in
The European Physical Journal C

The production of the hypermagnetic gyrotropy is investigated under the assumption that the gauge coupling smoothly evolves during a quasi-de Sitter phase and then flattens out in the radiation epoch by always remaining perturbative. In the plane defined by the strength of the anomalous interactions and by the rate of evolution of the gauge couplin...

Gresnigt, Niels G.
Published in
The European Physical Journal C

It is demonstrated that many of the assumed rules that govern the structure of a previously proposed topological preon model, in which simple non-trivial braids consisting of three twisted ribbons are mapped to the first generation of leptons and quarks, are automatically adhered to when the algebraic spinors of two complex Clifford algebras are id...