Related papers: Null Energy Condition Violations in Eternal Inflat…
We study constant roll inflation systematically. This is a regime, in which the slow roll approximation can be violated. It has long been thought that this approximation is necessary for agreement with observations. However, recently it was…
String/M theory inspires an uncertainty relation between space and time which deviates from general relativity. It is possible to explore this deviation from cosmological observations, in particular from the CMB fluctuation spectrum. This…
We analyze the energy density fluctuations contributed by scalar fields $\Phi$ with vanishing expectation values, $\langle\Phi\rangle=0$, which are present in addition to the inflaton field. For simplicity we take $\Phi$ to be…
We examine a scalar-tensor model of gravity that is globally scale-invariant. When adapted to a spatially flat Robertson-Walker metric, the equations of motion describe a dynamical system that flows from an unstable de Sitter space to a…
I investigate whether eternal inflation is possible when the inflaton originally travels upslope the scalar potential and inevitably reaches a turn-around point where its classical kinetic energy momentarily vanishes. This behaviour occurs…
If the cosmological inflationary scenario took place in the cosmic landscape in string theory, the inflaton, the scalar mode responsible for inflation, would have meandered in a complicated multi-dimensional potential. We show that this…
We investigate the initiation of cosmic inflation, in full numerical relativity, from pre-inflationary scenarios with large tensor and vector fluctuations in the metric. These settings are characterized by having large values in the Weyl…
We present a model of inflation where the inflaton is accommodated as a phantom field which exhibits an initial transient pole behavior and then decays into a quintessence field which is responsible for a radiation era. We must stress that…
At the end of the inflationary stage of the early universe, profuse particle production leads to the reheating of the universe. Such explosive particle production is due to parametric amplification of quantum fluctuations for the unbroken…
The Averaged Null Energy Condition (ANEC) requires that the average along a complete null geodesic of the projection of the stress-energy tensor onto the geodesic tangent vector can never be negative. It is sufficient to rule out many…
We have analyzed the spectral density of fluctuations of the energy flux through a mesoscopic constriction between two equilibrium reservoirs. It is shown that at finite frequencies, the fluctuating energy flux is not related to the thermal…
Semiclassical Physics in gravitational scenario, in its first approximation (1st order) cares only for the expectation value of stress energy tensor and ignores the inherent quantum fluctuations thereof. In the approach of stochastic…
The possibility that the non-minimal coupling inflation could be eternal is investigated. We calculate the quantum fluctuation of the inflaton in a Hubble time and find that it has the same value as in the minimal case in the slow-roll…
An outgrowth of the idea of inflation is advanced. In the inflation regime, the singularity condition is broken. Equations which govern inflation are invariant under time reversal, so that they describe deflation as well. Those two…
We clarify the role of the oft-misunderstood Null Energy Condition (NEC) in the context of the current cosmological data. In particular, the NEC implies the sum of the total energy density and pressure satisfies $\rho_{tot}+P_{tot} \ge 0$;…
Since inflationary perturbations must generically couple to all degrees of freedom present in the early Universe, it is more realistic to view these fluctuations as an open quantum system interacting with an environment. Then, on very…
In this work we investigate the inflationary era in the presence of a canonical scalar field and Chern-Simons parity violating corrections. It was also assumed that a non minimal coupling between curvature and the scalar field is present.…
It has recently been shown [1] that light vector particles produced from inflationary fluctuations can give rise to the dark matter in the Universe. A similar mechanism has been discussed in [2] for a non-minimally coupled scalar enjoying a…
We explore the possibility of a single field quasi-de Sitter inflationary model with general initial state for primordial fluctuations. In this paper, first we compute the power spectrum and the bispectrum of scalar perturbations with…
In discussions of Bousso's Covariant Entropy Bound, the Null Energy Condition is always assumed, as a sufficient {\em but not necessary} condition which helps to ensure that the entropy on any lightsheet shall necessarily be finite. The…