191 research outputs found
Emergently Thermalized Islands in the Landscape
In this note, we point out that in the eternal inflation driven by the
metastable vacua of the landscape, it might be possible that some large and
local quantum fluctuations with the null energy condition violation can stride
over the barriers between different vacua and straightly create some islands
with radiation and matter in new vacua. Then these thermalized islands will
evolve with the standard cosmology. We show that such islands may be consistent
with our observable universe, while has some distinctly observable signals,
which may be tested in coming observations.Comment: 4 pages, 1 eps figure, contents added and discussions extended,
publish in PL
On Primordial Density Perturbation and Decaying Speed of Sound
The decaying speed of sound can lead to the emergence of the primordial
density perturbation in any expanding phase, even if the expansion is
decelerated. Recently, some proposals have been given to implement this
mechanism, in which it was found that the primordial spectrum of scalar
perturbation can be scale invariant. In this note, we will give more insights
for the details of this seeding mechanism.Comment: 3 pages, 2 eps figure, contents extended, refs. added, published
version
Seeding of Primordial Perturbations During a Decelerated Expansion
A scalar field with a modified dispersion relation may seed, under certain
conditions, the primordial perturbations during a decelerated expansion. In
this note we examine whether and how these perturbations can be responsible for
the structure formation of observable universe. We discuss relevant
difficulties and possible solutions.Comment: 5 pages, 3 figures, more details and clarifications added, refs.
added, new version with 6 pages has been splitted into various sections, to
be published in PRD, v3, matched to published versio
Preheating in Bubble Collisions
In a landscape with metastable minima, the bubbles will inevitably nucleate.
We show that during the bubbles collide, due to the dramatically oscillating of
the field at the collision region, the energy deposited in the bubble walls can
be efficiently released by the explosive production of the particles. In this
sense, the collision of bubbles is actually highly inelastic. The cosmological
implications of this result are discussed.Comment: 5 pages, 4 figs, discussion improved, refs. added, and Fig.3 revised,
to publish in PR
- …