相关论文: A comment on trans-Planckian physics in inflationa…

We show that a conformal-invariance violating coupling of the inflaton to electromagnetism produces a cross correlation between curvature fluctuations and a spectrum of primordial magnetic fields. According to this model, in the case of…

We show that current cosmic acceleration can be explained by an almost massless scalar field experiencing quantum fluctuations during primordial inflation. Provided its mass does not exceed the Hubble parameter today, this field has been…

Recent detection of $B$-mode polarization induced from tensor perturbations by the BICEP2 experiment implies so-called large field inflation, where an inflaton field takes super-Planckian expectation value during inflation, at a high energy…

The weak gravity conjecture applied for the aligned natural inflation indicates that generically there can be a modulation of the inflaton potential, with a period determined by sub-Planckian axion scale. We study the oscillations in the…

We derive an uncertainty relation for the energy density and pressure of a quantum scalar field in a time-dependent, homogeneous and isotropic, classical background, which implies the existence of large fluctuations comparable to their…

Inflation offers a simple model for very early evolution of our Universe and the origin of primordial perturbations on large scales. Over the last 25 years we have become familiar with the predictions of single-field models, but inflation…

We conjecture that the inflation models with trans-Planckian excursions in the field space should be in the swampland. We check this conjecture in a few examples and investigate the constraints on the spectral index for the slow-roll…

Recently, there has been some interest for building supersymmetric models of double inflation. These models, realistic from a particle physics point of view, predict a broken-scale-invariant power spectrum of primordial cosmological…

In the context of single field inflation, models with a quadratic potential and models with a natural potential with subplanckian decay constant are in tension with the Planck data. We show that, when embedded in a two-field model with an…

Cosmological inflation is discussed in the realm of Einstein-Cartan-Brans-Dicke (ECBD) gravity by constructing an effective inflaton potential and computing the number of e-folds.It is shown that spin-torsion density contributes to a…

We consider the influence of mode - mode coupling in the inflaton field on the spectrum of primordial fluctuations. To this end, we formulate a phenomenological model where the inflaton fluctuations are treated as a fluid undergoing…

Fluctuations in high-redshift cosmic 21-cm radiation provide a new window for observing unconventional effects of high-energy physics in the primordial spectrum of density perturbations. In scenarios for which the initial state prior to…

The scale--independence of the primordial curvature perturbation suggests that it comes from the vacuum fluctuation during inflation of a light scalar field. This field may be the inflaton, or a different `curvaton' field. The observation…

We discuss the effect of super-Hubble cosmological fluctuations on the locally measured Hubble expansion rate. We consider a large bare cosmological constant in the early universe in the presence of scalar field matter (the dominant matter…

The early universe according to the big bang and the grand unified theories is discussed. The shortcomings of big bang are summarized together with their resolution by inflationary cosmology. Inflation, the subsequent oscillation and decay…

An inflationary brane model driven by a bulk inflaton with exponential potential is proposed. We find a family of exact solutions that describe power-law inflation on the brane. These solutions enable us to derive exact solutions for metric…

We study the behavior of large-scale (cosmological) modes of back-reaction effects during inflation. We find that the group of modes which describes the very large-scale fluctuations of energy density during inflation due to back-reaction…

We study primordial perturbations generated from quantum fluctuations of an inflaton based on the formalism of stochastic gravity. Integrating out the degree of freedom of the inflaton field, we analyze the time evolution of the correlation…

In this paper we study the generation of primordial perturbation with a modified dispersion relation in various cosmological evolutions. We stress that the formation of the power spectrum is strongly dependent on the background. Working in…

Decoupling of heavy modes in effective low energy theory is one of the most fundamental concepts in physics. It tells us that modes must have a negligible effect on the physics of gravitational backgrounds with curvature radius larger than…