Related papers: Metric fluctuations and its evolution during infla…
Heavy scalar fields can undergo an instability during inflation as a result of their kinetic couplings with the inflaton. This is known as the geometrical destabilization of inflation, as it relies on the effect of the negative curvature of…
By assuming the kinetic coupling $f^{2}(\phi)FF$ of the effective inflaton field $\phi$ with the electromagnetic field, we explore magnetogenesis during the inflation and preheating stages in the Starobinsky model. We consider the case of…
Slow-roll inflation can be studied as an effective field theory. The form of the inflaton potential consistent with the data is V(phi) = N M^4 w(phi/[sqrt{N} M_{Pl}]) where phi is the inflaton field, M is the inflation energy scale, and N ~…
We consider preheating in models in which the potential for the inflaton is given by a fractional power, as is the case in axion monodromy inflation. We assume a standard coupling between the inflaton field and a scalar matter field. We…
We study the class of two-field inflationary Universe models \lambda\phi^4/4 + g^2\chi^2\phi^2/2, in which parametric resonance during the initial stages of reheating can lead to an exponential amplification of the amplitude of cosmological…
We investigate the inflation of Universe in a model of four dimensional dilatonic gravity with a massive dilaton field $\Phi$. The dilaton plays simultaneously the roles of an inflation field and a quintessence field. It yields a sequential…
We investigate inflation within $f(R,\phi)$-theories, where a dynamical scalar field is coupled to gravity. A class of models which can support early-time acceleration with the emerging of an effective cosmological constant at high…
We examine the classical dynamics of multifield inflation models with quadratic potentials. Such models are shown to have inflationary attractors in phase space, consistent with the stretching of phase space trajectories along the volume…
We study DBI inflation based upon a general model characterized by a power-law flow parameter $\epsilon(\phi)\propto\phi^{\alpha}$ and speed of sound $c_s(\phi)\propto\phi^{\beta}$, where $\alpha$ and $\beta$ are constants. We show that in…
I study a fresh inflationary model with a scalar field nonminimally coupled to gravity. An example is examined. I find that, as larger is the value of $p$ (the power of the scale factor), smaller (but larger in its absolute value) is the…
We further clarify how scalar metric perturbations are amplified in an inflationary cosmology. We first construct a simple, analytic model of an inflationary cosmology in which the expansion scale factor evolves continuously from an…
This is an old article which has never been posted for public use and which only appeard in a relatively hard-to-get Proceedings of the Sakharov Conference in Moscow (May, 1991). The subject of this article has received a lot of attention…
Moduli fields, which parameterize perturbative flat directions of the potential in supersymmetric theories, are natural candidates to act as inflatons. An inflationary potential on moduli space can result if the scale of dynamical SUSY…
Multiple field models of inflation exhibit new features than single field models. In this work, we study the hierarchy of parameters based on Hubble expansion rate in curved field space and derive the system of flow equations that describe…
We study the generation of electromagnetic fields during inflation when the conformal invariance of Maxwell's action is broken by the kinetic coupling $f^{2}(\phi)F_{\mu\nu}F^{\mu\nu}$ of the electromagnetic field to the inflaton field…
We study the spectrum of metric fluctuation in $\kappa$-deformed inflationary universe. We write the theory of scalar metric fluctuations in the $\kappa-$deformed Robertson-Walker space, which is represented as a non-local theory in the…
The effective equation of motion is derived for a scalar field interacting with other fields in a Friedman-Robertson-Walker background space-time. The dissipative behavior reflected in this effective evolution equation is studied both in…
We explore extensions of hybrid inflationary models in the context of supersymmetric D-term inflation. We point out that a large variety of inflationary scenarios can be encountered when the field content is extended. It is not only…
In this paper, we calculate the spectrum of scalar field fluctuations in a bouncing, asymptotically flat Universe, and investigate the dependence of the result on changes in the physics on length scales shorter than the Planck length which…
We consider a market where many agents trade many different types of products with each other. We model development of collective modes in this market, and quantify these by fluctuations that scale with time with a Hurst exponent of about…