相关论文: Initial conditions in hybrid inflation: exploratio…

In order to generate more than 60 e-folds of accelerated expansion in original hybrid inflation, 2-fields trajectories are usually required to be initially fine-tuned in a very narrow band along the inflationary valley or in some isolated…

We show that the initial field values required to produce inflation in the two fields original hybrid model, and its supergravity F-term extension, do not suffer from any fine-tuning problem, even when the fields are restricted to be…

We investigate the initial conditions problem for multifield inflation. In these scenarios the pre-inflationary dynamics can be chaotic, increasing the sensitivity of the onset of inflation to the initial data even in the homogeneous limit.…

We study the evolution of regions of space with various initial field values for a simple theory that can support hybrid inflation. Only very narrow domains within the range of initial field values below the Planck scale lead to the onset…

Hybrid inflation faces two well-known problems: the blue spectrum of the non-supersymmetric version of the model and the fine-tuning of the initial conditions of the fields leading to sufficient inflation to account for the standard…

In hybrid inflation models, typically only a tiny fraction of possible initial conditions give rise to successful inflation, even if one assumes spatial homogeneity. We analyze some possible solutions to this initial conditions problem,…

We study the presence of chaotic behavior in phase space in the pre-inflationary stage of hybrid inflation models. This is closely related to the problem of initial conditions associated to these inflationary type of models. We then show…

The dynamics of hybrid models is usually approximated by the evolution of a scalar field slowly rolling along a nearly flat valley. Inflation ends with a waterfall phase, due to a tachyonic instability. This final phase is usually assumed…

We perform a numerical investigation of the field evolution in the smooth hybrid inflationary model. We find that for almost all the examined initial values we do get an adequate amount of inflation. Our results show that the model is…

We investigate the circumstances under which cosmic inflation can arise from very inhomogeneous initial conditions using numerical relativity simulations. Previous studies have not considered cases with non-zero momentum density due to…

We discuss the issue of setting appropriate initial conditions for inflation. Specifically, we consider natural inflation model and discuss the fine tuning required for setting almost homogeneous initial conditions over a region of order…

We consider observational constraints and fine-tuning issues in a renormalizable model of inflection point inflation, with two independent parameters. We derive constraints on the parameter space of this model arising from the WMAP 7-year…

Cosmological inflation is the dominating paradigm to account for observations of the Cosmic Microwave Background (CMB). In this thesis, we study the phenomenology of a class of particularly well motivated models of inflation, known under…

While cosmological inflation can erase primordial inhomogeneities, it is possible that inflation may not begin in a significantly inhomogeneous universe. This issue is particularly pressing in multifield scenarios, where even the…

Small-field inflation typically requires rather special initial conditions to commence. It is proposed that in models where the inflaton is an axionlike field, with a periodic contribution to the potential, there is a possibility of…

The BICEP2 observations, if confirmed, point to a high scale of inflation and large field excursions during the inflationary era. Non-compact string moduli spaces are a suggestive setting for these phenomena. While unlikely to be described…

We address the issue of fine-tuning of the initial field configuration that can lead to hybrid inflation in the context of global supersymmetry. This problem is generated by the difference between the energy scale at which the Universe…

We investigate the dynamics of homogeneous phase space for single-field models of inflation. Inflationary trajectories are formally attractors in phase space, but since in practice not all initial conditions lead to them, some degree of…

We explore inflation via the effective potential of the minimal Wess-Zumino model, considering both the real and imaginary components of the complex field. Using transport techniques, we calculate the full allowed range of $n_s$, $r$ and…

We investigate the parameter space of hybrid inflation models where inflation terminates via a first-order phase transition causing nucleation of bubbles. Such models experience a tension from the need to ensure nearly scale invariant…