29 research outputs found
Features and implications of the plateau inflationary potentials
After the last PLANCK CMB data the plateau inflationary potentials are
favored. I give some examples of such inflationary models emphasizing
particularly on the Starobinsky model and its supergravity embedding. I discuss
the crucial implications, regarding the initial conditions problem, of this new
sort of potentials for the standard picture of the inflationary theory.Comment: 10 pages, 5 figures, prepared for Planck 2015 conference. 25-29 May
2015. Ioannina, Greece CNUM: C15-05-25.
Constrained superfields from inflation to reheating
We construct effective supergravity theories from customized constrained
superfields which provide a setup consistent both for the description of
inflation and the subsequent reheating processes. These theories contain the
minimum degrees of freedom in the bosonic sector required for single-field
inflation.Comment: Physics Letters B journal version, 16 pages, plain tex
Thermally Favourable Gauge Mediation
We discuss the thermal evolution of the spurion and messenger fields of
ordinary gauge mediation models taking into account the Standard Model degrees
of freedom. It is shown that for thermalized messengers the metastable susy
breaking vacuum becomes thermally selected provided that the susy breaking
sector is sufficiently weakly coupled to messengers or to any other observable
field.Comment: 11 pages, 6 figures, plain latex; numerical factors corrected, final
versio
Features in the Inflaton Potential and the Spectrum of Cosmological Perturbations
Cosmological perturbations, originating in the quantum fluctuations of the
fields that drive inflation, are observed to be nearly scale invariant at the
largest scales. At smaller scales, however, perturbations are not severely
constrained and might be of particular importance if their amplitude is large.
They can trigger the creation of primordial black holes (PBHs) or stochastic
gravitational waves (GWs). Small-scale perturbations are generated during the
later stages of inflation, when possible strong features in the inflaton
potential can break scale invariance and leave characteristic imprints on the
spectrum. We focus on and review three types of features: inflection points and
steep steps in the potential, as well as sharp turns in the inflationary
trajectory in field space. We show that such features induce a strong
enhancement of the curvature spectrum within a certain wavenumber range. In
particular cases, they also generate characteristic oscillatory patterns that
are transferred in the spectrum of secondary GWs, which are potentially
observable by operating or designed experiments. We demonstrate these effects
through the calculation of the primordial power spectrum and the PBH abundance
in the context of -attractors and supergravity (SUGRA) models of
inflation.Comment: 26 pages, 8 figures. Topical review presented at the 11th Aegean
Summer Schoo
Suppressing gravitino thermal production with a temperature-dependent messenger coupling
We show that the constraints on GMSB theories from the gravitino cosmology
can be significantly relaxed if the messenger-spurion coupling is temperature
dependent. We demonstrate this novel mechanism in a scenario in which this
coupling depends on the VEV of an extra singlet field that interacts with
the thermalized plasma which can result in a significantly suppressed gravitino
production rate. In such a scenario the relic gravitino abundance is determined
by the thermal dynamics of the field and it is easy to fit the observed
dark matter abundance evading the stringent constraints on the reheating
temperature, thus making gravitino dark matter consistent with thermal
leptogenesis.Comment: 27 pages, 6 figures, 3 tables, plain tex
Probing the BSM physics with CMB precision cosmology: an application to supersymmetry
The cosmic history before the BBN is highly determined by the physics that
operates beyond the Standard Model (BSM) of particle physics and it is poorly
constrained observationally. Ongoing and future precision measurements of the
CMB observables can provide us with significant information about the pre-BBN
era and hence possibly test the cosmological predictions of different BSM
scenarios. Supersymmetry is a particularly motivated BSM theory and it is often
the case that different superymmetry breaking schemes require different cosmic
histories with specific reheating temperatures or low entropy production in
order to be cosmologically viable. In this paper we quantify the effects of the
possible alternative cosmic histories on the and CMB observables
assuming a generic non-thermal stage after cosmic inflation. We analyze TeV and
especially multi-TeV supersymmetry breaking schemes assuming the neutralino and
gravitino dark matter scenarios. We complement our analysis considering the
Starobinsky inflation model to exemplify the improved CMB predictions
that a unified description of the early universe cosmic evolution yields. Our
analysis underlines the importance of the CMB precision measurements that can
be viewed, to some extend, as complementary to the laboratory experimental
searches for supersymmetry or other BSM theories.Comment: 52 pages, 13 figures, plain tex