The European Physical Journal C

List of Papers (Total 3,638)

Stratified scalar field theories of gravitation with self-energy term and effective particle Lagrangian

We construct a general stratified scalar theory of gravitation from a field equation that accounts for the self-interaction of the field and a particle Lagrangian, and calculate its post-Newtonian parameters. Using this general framework, we analyze several specific scalar theories of gravitation and check their predictions for the solar system post-Newtonian effects.

Analysis of b quark pair production signal from neutral 2HDM Higgs bosons at future linear colliders

In this paper, the b quark pair production events are analyzed as a source of neutral Higgs bosons of the two Higgs doublet model type I at linear colliders. The production mechanism is $e^{+}e^{-} \rightarrow Z^{(*)} \rightarrow HA \rightarrow b{\bar{b}}b{\bar{b}}$ assuming a fully hadronic final state. The analysis aim is to identify both CP-even and CP-odd Higgs bosons in...

Some results on a black hole with a global monopole in Poincaré gravity

The aim of this work is to study the thermodynamics and spin current of a system corresponding to a black hole containing a global monopole in the context of Poincaré gravity theory which is an extension of general relativity, in the sense that the intrinsic angular momentum of matter is also a source of gravitational interaction. Thus, in this work we find the solution...

Palatini formulation of f(R, T) gravity theory, and its cosmological implications

We consider the Palatini formulation of f(R, T) gravity theory, in which a non-minimal coupling between the Ricci scalar and the trace of the energy-momentum tensor is introduced, by considering the metric and the affine connection as independent field variables. The field equations and the equations of motion for massive test particles are derived, and we show that the...

On stability of a neutron star system in Palatini gravity

We formulate the generalized Tolman–Oppenheimer–Volkoff equations for the $f(\hat{R})$ Palatini gravity in the case of static and spherical symmetric geometry. We also show that a neutron star can be a stable system independently of the form of the functional $f(\hat{R})$.

Non-perturbative to perturbative QCD via the FFBRST

Recently a new type of quadratic gauge was introduced in QCD in which the degrees of freedom are suggestive of a phase of abelian dominance. In its simplest form it is also free of Gribov ambiguity. However this gauge is not suitable for usual perturbation theory. The finite field dependent BRST (FFBRST) transformation is a method established to interrelate generating functionals...

The minimal axion minimal linear $\sigma$ model

The minimal SO(5) / SO(4) linear $\sigma$ model is extended including an additional complex scalar field, singlet under the global SO(5) and the Standard Model gauge symmetries. The presence of this scalar field creates the conditions to generate an axion à la KSVZ, providing a solution to the strong CP problem, or an axion-like-particle. Different choices for the PQ charges...

Stephani cosmology: entropically viable but observationally challenged

Inhomogeneous cosmological models such as the Stephani universes could, in principle, provide an explanation for the observed accelerated expansion of the Universe. Working with a concrete, popular model of the Stephani cosmology – the Stephani-Da̧browski model, we found that it is entropically viable. We also comment on the energy conditions and the two-sheeted geometry of the...

This paper deals with the cancellation mechanism, which identifies the energy density of space-time expansion in an empty universe with the zero-point energy density and avoids the scale discrepancy with the observed energy density (cosmological constant problem). Using an intrinsic degree of freedom which describes the coupling of a variable cosmological term $\varLambda... Search for a new heavy gauge-boson resonance decaying into a lepton and missing transverse momentum in 36 fb \(^{-1}$ of pp collisions at $\sqrt{s} = 13$ TeV with the ATLAS experiment

The results of a search for new heavy $W^\prime$ bosons decaying to an electron or muon and a neutrino using proton–proton collision data at a centre-of-mass energy of $\sqrt{s}~=~13$ TeV are presented. The dataset was collected in 2015 and 2016 by the ATLAS experiment at the Large Hadron Collider and corresponds to an integrated luminosity of 36.1 $\text{ fb }^{-1}$. As...

Bouncing cosmological solutions from $f(\mathsf{R,T})$ gravity

In this work we study classical bouncing solutions in the context of $f(\mathsf{R},\mathsf{T})=\mathsf{R}+h(\mathsf{T})$ gravity in a flat FLRW background using a perfect fluid as the only matter content. Our investigation is based on introducing an effective fluid through defining effective energy density and pressure; we call this reformulation as the “effective picture...

Scalar pair production in a magnetic field in de Sitter universe

The production of scalar particles by the dipole magnetic field in de Sitter expanding universe is analyzed. The amplitude and probability of transition are computed using perturbative methods. A graphical study of the transition probability is performed obtaining that the rate of pair production is important in the early universe. Our results prove that in the process of pair...

On the trajectories of null and timelike geodesics in different wormhole geometries

The paper deals with an extensive study of null and timelike geodesics in the background of wormhole geometries. Starting with a spherically symmetric spacetime, null geodesics are analyzed for the Morris–Thorne wormhole (WH) and photon spheres are examined in WH geometries. Both bounded and unbounded orbits are discussed for timelike geodesics. A similar analysis has been done...

Gravitational decoupled anisotropies in compact stars

Simple generic extensions of isotropic Durgapal–Fuloria stars to the anisotropic domain are presented. These anisotropic solutions are obtained by guided minimal deformations over the isotropic system. When the anisotropic sector interacts in a purely gravitational manner, the conditions to decouple both sectors by means of the minimal geometric deformation approach are satisfied...

Fayet–Iliopoulos terms in supergravity and D-term inflation

We analyse the consequences of a new gauge invariant Fayet–Iliopoulos (FI) term proposed recently to a class of inflation models driven by supersymmetry breaking with the inflaton being the superpartner of the goldstino. We first show that charged matter fields can be consistently added with the new term, as well as the standard FI term in supergravity in a Kähler frame where the...

Estimating decay rate of $X^{{\pm }}(5568)\rightarrow B_s\pi ^{{\pm }}$ while assuming them to be molecular states

Discovery of X(5568) brings up a tremendous interest because it is very special, i.e. made of four different flavors. The D0 collaboration claimed that they observed this resonance through portal $X(5568)\rightarrow B_s\pi$, but unfortunately, later the LHCb, CMS, CDF and ATLAS collaborations’ reports indicate that no such state was found. Almost on the Eve of 2017, the D0...

Mass-induced instability of SAdS black hole in Einstein–Ricci cubic gravity

We perform the stability analysis of Schwarzschild-AdS (SAdS) black hole in the Einstein–Ricci cubic gravity. It shows that the Ricci tensor perturbations exhibit unstable modes for small black holes. We call this the mass-induced instability of SAdS black hole because the instability of small black holes arises from the massiveness in the linearized Einstein–Ricci cubic gravity...

A unified universe

We present a unified evolution of the universe from very early times until the present epoch by including both the leading local correction $R^2$ and the leading non-local term $R\frac{1}{\square ^2}R$ to the classical gravitational action. We find that the inflationary phase driven by $R^2$ term gracefully exits in a transitory regime characterized by coherent oscillations...

Holographic insulator/superconductor transition with exponential nonlinear electrodynamics probed by entanglement entropy

From the viewpoint of holography, we study the behaviors of the entanglement entropy in insulator/superconductor transition with exponential nonlinear electrodynamics (ENE). We find that the entanglement entropy is a good probe to the properties of the holographic phase transition. Both in the half space and the belt space, the non-monotonic behavior of the entanglement entropy...