相关论文: Gravitational effects on oscillon lifetimes

We study an inflation mechanism based on attractor properties in cosmological evolutions of a spatially flat Friedmann-Robertson-Walker spacetime based on the Einstein-scalar field theory. We find a new way to get the Hamilton-Jacobi…

We have investigated a brane world model in which the gravitational field in the bulk is described both by a metric tensor and a minimally coupled scalar field. This scalar field is taken to be a chameleon with an appropriate potential…

Models of inflation based on axions, which owe their popularity to the robustness against UV corrections, have also a very distinct class of signatures. The relevant interactions of the axion are a non-perturbative oscillating contribution…

In the present thesis, using an effective field theory point of view, we explore theories of single-field inflation where higher derivative operators become relevant, affecting in a novel way the dynamics and therefore the observations. For…

We investigate the existence and behavior of oscillons in theories in which higher derivative terms are present in the Lagrangian, such as galileons. Such theories have emerged in a broad range of settings, from higher-dimensional models,…

We investigate the coupled system of gravity and a scalar with exponential potential. The energy momentum tensor of the scalar field induces a time-dependent cosmological ``constant''. This adjusts itself dynamically to become in the…

In this study, we analyse how quantisation of space-time affects propagating fermions in the presence of gravity. Effect of gravity is incorporated using spin connection which consists of universal torsion-free Levi-Civita connection and…

Gravitational stability of torsion and inflaton field in a four-dimensional spacetime de Sitter solution in scalar-tensor cosmology where Cartan torsion propagates is investigated in detail. Inflaton and torsion evolution equations are…

We investigate how coherent oscillations backreact on the evolution of the condensate wave function of ultra-light axions in the non-relativistic regime appropriate to cosmic structure formation. The coherent oscillations induce higher…

In most current models of inflation based on a weakly self-coupled scalar matter field minimally coupled to gravity, the period of inflation lasts so long that, at the beginning of the inflationary period, the physical wavelengths of…

A generic feature of string compactifications is the presence of many scalar fields, called moduli. Moduli are usually displaced from their post-inflationary minimum during inflation. Their relaxation to the minimum could lead to the…

We show that the inclusion of an axion-like effective potential in the construction of a self-gravitating system made of scalar fields leads to a decrease on its compactness when the value of the self-interaction coupling constant is…

According to recent reports there is an excess correlation and an apparent regularity in the galaxy one-dimensional polar distribution with a characteristic scale of 128 $h^{-1}$ Mpc. This aparent spatial periodicity can be naturally…

We study the effects of oscillating, ultralight scalar and pseudoscalar fields on the propagation of gravitational waves (GWs). We consider two potential couplings of the (pseudo)scalars to gravity; a parity-even Gauss-Bonnet coupling, and…

This work presents the dynamic properties of charged test particles influenced by the gravitational and electromagnetic fields. Accordingly, in this work, we concentrate on the static and axially symmetric metric containing two quadrupole…

We discuss gravitational effects of global scalar fields and, especially, of global topological defects. We first give an introduction to the dynamics of global fields and the formation of defects. Next we investigate the induced…

Oscillations in the frequency profile of the scalar-induced contribution to the stochastic gravitational wave background are a characteristic signal for small-scale features during inflation. We investigate how this oscillatory frequency…

Recently Mendonca and Cardoso [Phys. Rev. D, vol. 66, 104009 (2002)] considered nonlinear gravitational wave packets propagating in flat space-time. They concluded that the evolution equation - to third order in amplitude - takes a similar…

In this work, we investigate the cosmological dynamics of the $f(R, \mathcal{L}_m)$ gravity framework with a particular focus on the contributions of the scalar field. Considering a functional form that includes linear and exponential…

In this paper the scalar-tensor theory of gravity is assumed to describe the evolution of the universe and the gravitational scalar $\phi$ is ascribed to play the role of inflaton. The theory is characterized by the specified coupling…