The European Physical Journal C

List of Papers (Total 3,700)

Einstein–Yang–Mills AdS black brane solution in massive gravity and viscosity bound

We introduce the Einstein–Yang–Mills AdS black brane solution in context of massive gravity. The ratio of shear viscosity to entropy density is calculated for this solution. This value violates the KSS bound if we apply the Dirichlet boundary and regularity on the horizon conditions.

Non-truncated strategy to exactly integrate the post-Newtonian Lagrangian circular restricted three-body problem

In this study, we present a novel non-truncated strategy by accompanying the fixed-point iteration with traditional numerical integrators. The proposed non-truncated strategy aims to exactly integrate implicit motion equations that are directly derived from the Lagrangian of the post-Newtonian circular restricted three-body problem. In comparison with the commonly used truncated...

Photon sector analysis of Super and Lorentz symmetry breaking: effective photon mass, bi-refringence and dissipation

Within the standard model extension (SME), we expand our previous findings on four classes of violations of Super-Symmetry (SuSy) and Lorentz Symmetry (LoSy), differing in the handedness of the Charge conjugation-Parity-Time reversal (CPT) symmetry and in whether considering the impact of photinos on photon propagation. The violations, occurring at the early universe high...

Growth of matter overdensities in non-minimal torsion-matter coupling theories

We study the evolution of cosmological perturbations around a homogeneous and isotropic background in the framework of the non-minimal torsion-matter coupling extension of f(T) gravity. We are concerned with the effects of the non-minimal coupling term on the growth of matter overdensities. Under the quasi-static approximation, we derive the equation which governs the evolution...

Search for new physics in dijet angular distributions using proton–proton collisions at $$\sqrt{s}=13\hbox {TeV}$$ and constraints on dark matter and other models

A search is presented for physics beyond the standard model, based on measurements of dijet angular distributions in proton–proton collisions at $$\sqrt{s}=13\hbox {TeV}$$. The data collected with the CMS detector at the LHC correspond to an integrated luminosity of 35.9$$\,\text {fb}^{-1}$$. The observed distributions, corrected to particle level, are found to be in agreement...

Following the primordial perturbations through a bounce with AdS/CFT correspondence

A bounce universe model, known as the coupled-scalar-tachyon bounce (CSTB) universe, has been shown to solve the Horizon, Flatness and Homogeneity problems as well as the Big Bang singularity problem. Furthermore a scale invariant spectrum of primordial density perturbations generated from the phase of pre-bounce contraction is shown to be stable against time evolution. In this...

Lower bound on the radii of circular orbits in the extremal Kerr black-hole spacetime

It is often stated in the physics literature that maximally-spinning Kerr black-hole spacetimes are characterized by near-horizon co-rotating circular geodesics of radius $$r_{\text {circular}}$$ with the property $$r_{\text {circular}}\rightarrow r^+_{\text {H}}$$, where $$r_{\text {H}}$$ is the horizon radius of the extremal black hole. Based on the famous Thorne hoop...

Cosmological constant constraints from observation-derived energy condition bounds and their application to bimetric massive gravity

Among the various possibilities to probe the theory behind the recent accelerated expansion of the universe, the energy conditions (ECs) are of particular interest, since it is possible to confront and constrain different theories of gravity with observational data. In this context, we use the ECs to probe any alternative theory of gravity whose extra term acts as a cosmological...

Effects of quantum statistics on relic density of dark radiation

The freeze-out of massless particles is investigated. The effects due to quantum statistics, Fermi-Dirac or Bose-Einstein, of all particles relevant for the process are analyzed. Solutions of appropriate Boltzmann equation are compared with those obtained using some popular approximate methods. As an application of general results the relic density of dark radiation in Weinberg’s...

Top quark FCNCs in extended Higgs sectors

The large number of top quarks produced at the LHC and possible future hadron colliders allows to study rare decays of this particle. In many well motivated models of new physics, for example in non-minimal composite-Higgs models, the existence of scalar singlets can induce new flavor-violating top decays surpassing the Higgs contribution by orders of magnitude. We study the...

Long-term monitoring of the ANTARES optical module efficiencies using $$^{40}\mathrm{{K}}$$ decays in sea water

Cherenkov light induced by radioactive decay products is one of the major sources of background light for deep-sea neutrino telescopes such as ANTARES. These decays are at the same time a powerful calibration source. Using data collected by the ANTARES neutrino telescope from mid 2008 to 2017, the time evolution of the photon detection efficiency of optical modules is studied. A...

First law of inner mechanics of black holes in generalized minimal massive gravity

In this paper, we examine the validity of the first law of inner mechanics of black holes in Generalized Minimal Massive Gravity. We consider BTZ and spacelike warped black holes and show that the first law of inner mechanics is valid for given black holes in Generalized Minimal Massive Gravity. As we expect, due to the presence of the Lorentz Chern–Simons term in Lagrangian of...

Tsallis $$\delta$$ -entropy in an accelerating BIon

In this research, we consider thermodynamically the behaviour of an accelerating BIon and show that the entropy of this system has the form of Tsallis entropy. A BIon is a system that consists of a brane, an anti-brane and a wormhole which connects them together. By increasing the acceleration of branes, the area of BIon increases and its Tsallis entropy grows.

Neutrino oscillations and Lorentz invariance violation in a Finslerian geometrical model

Neutrino oscillations are one of the first evidences of physics beyond the Standard Model (SM). Since Lorentz invariance is a SM fundamental symmetry, recently also neutrino physics has been explored to verify this symmetry eventual modification and its potential magnitude. In this work we study the Lorentz invariance violation (LIV) introduction consequences in the high energy...

Analytical and numerical study of backreacting one-dimensional holographic superconductors in the presence of Born–Infeld electrodynamics

We analytically as well as numerically study the effects of Born–Infeld nonlinear electrodynamics on the properties of $$(1+1)$$-dimensional s-wave holographic superconductors. We relax the probe limit and further assume the scalar and gauge fields to affect the background spacetime. We thus explore the effects of backreaction on the condensation of the scalar hair. For the...

Accelerating AdS black holes as the holographic heat engines in a benchmarking scheme

We investigate the properties of holographic heat engines with an uncharged accelerating non-rotating AdS black hole as the working substance in a benchmarking scheme. We find that the efficiencies of the black hole heat engines can be influenced by both the size of the benchmark circular cycle and the cosmic string tension as a thermodynamic variable. In general, the efficiency...

Momentum dissipation and holographic transport without self-duality

We explore the response of the momentum dissipation introduced by spatial linear axionic fields in a holographic model without self-duality, which is broke by Weyl tensor coupling to Maxwell field. It is found that for the positive Weyl coupling parameter $$\gamma >0$$, the momentum dissipation, characterized by parameter $${\hat{\alpha }}$$, drives an incoherent metallic state...

A note on thin-shell wormholes with charge in F(R)-gravity

In their recent work (Eiroa and Aguirre in Eur Phys J C 76:132, 2016), Eiroa and Aguirre introduced thin-shell wormholes in $$F\left( R\right) =R+\alpha R^{2}$$-gravity coupled with the Maxwell electromagnetic field. Here in this note we shall address an interesting feature of their results which has been missed. It will be shown that thin-shell wormhole can not be formed in the...

Colour rearrangement for dipole showers

We present an algorithm to rearrange the colour chains of dipole showers in the shower process according to the colour amplitudes of a simple matrix element. We implement the procedure in the dipole shower of Herwig and show comparisons to data.

Stochastic inflation with quantum and thermal noise

We add a thermal noise to Starobinsky equation of slow roll inflation. We calculate the number of e-folds of the stochastic system. The power spectrum and the spectral index are evaluated from the fluctuations of the e-folds using an expansion in the quantum and thermal noise terms.

Galactic rotation dynamics in f(T) gravity

We investigate galactic rotation curves in f(T) gravity, where T represents a torsional quantity. Our study centers on the particular Lagrangian $$f(T)=T+\alpha {T^n}$$, where $$|n|\ne 1$$ and $$\alpha$$ is a small unknown constant. To do this we treat galactic rotation curves as being composed from two distinct features of galaxies, namely the disk and the bulge. This process...

Collapse of the wavefunction, the information paradox and backreaction

We consider the black hole information problem within the context of collapse theories in a scheme that allows the incorporation of the backreaction to the Hawking radiation. We explore the issue in a setting of the two dimensional version of black hole evaporation known as the Russo-Susskind-Thorlacius model. We summarize the general ideas based on the semiclassical version of...