3,692 research outputs found
Higgs inflation and vacuum stability
Inflation is nowadays a well-established paradigm consistent with all the
observations. The precise nature of the inflaton is however unknown and its
role could be played by any candidate able to imitate a scalar condensate in
the slow-roll regime. The discovery of a fundamental scalar in the LHC provides
the less speculative candidate. Could the Higgs field itself be responsible for
inflation? Do we really need to advocate new physics to explain the properties
of the Universe at large scales? Which is the relation between the Standard
Model parameters and the inflationary observables? What happens if our vacuum
becomes unstable below the scale of inflation? We present an overview of Higgs
inflation trying to provide answers to the previous questions with special
emphasis on the vacuum stability issue.Comment: 11 pages, 14 figures, contribution to proceedings DISCRETE 201
Higgs-Dilaton cosmology: Universality vs. criticality
The Higgs-Dilaton model is able to produce an early inflationary expansion
followed by a dark energy dominated era responsible for the late time
acceleration of the Universe. At tree level, the model predicts a small
tensor-to-scalar ratio (), a tiny negative running of
the spectral tilt () and a nontrivial
consistency relation between the spectral tilt of scalar perturbations and the
dark energy equation of state, which turns out to be close to a cosmological
constant (). We reconsider the validity of these
predictions in the vicinity of the critical value of the Higgs self-coupling
giving rise to an inflection point in the inflationary potential. The value of
the inflationary observables in this case strongly depends on the parameters of
the model. The tensor-to-scalar ratio can be large [] and
notably exceed its tree-level value. If that happens, the running of the scalar
tilt becomes positive and rather big [] and
the equation-of-state parameter of dark energy can significantly differ from a
cosmological constant [].Comment: 5 pages, 3 figures, published version, added clarifications and
references, corrected typo
Quintessential Affleck-Dine baryogenesis with non-minimal couplings
We present a novel Affleck-Dine scenario for the generation of the observed
baryon asymmetry of the Universe based on the non-trivial interplay between
quintessential inflationary models containing a kinetic dominated
post-inflationary era and a non-minimally coupled field with a weakly
broken symmetry. The non-minimal coupling to gravity renders heavy the
Affleck-Dine field during inflation and avoids the generation of isocurvature
fluctuations. During the subsequent kinetic era the Ricci scalar changes sign
and the effective mass term of the Affleck-Dine field becomes tachyonic. This
allows the field to dynamically acquire a large expectation value. The symmetry
of the Affleck-Dine potential is automatically restored at the onset of
radiation domination, when the Ricci scalar approximately equals zero. This
inverse phase transition results in the coherent oscillation of the scalar
field around the origin of its effective potential. The rotation of the
displaced Affleck-Dine field in the complex plane generates a non-zero
asymmetry which can be eventually converted into a baryon asymmetry via the
usual transfer mechanisms.Comment: 9 pages, 1 figure, minor corrections and clarifications added.
Matches the published versio
Endlessly flat scalar potentials and -attractors
We consider a minimally-coupled inflationary theory with a general scalar
potential containing a
stationary point of maximal order . We show that asymptotically flat
potentials can be associated to stationary points of infinite order and discuss
the relation of our approach to the theory of -attractors.Comment: 8 pages, 2 figure
A nonparametric dimension test of the term structure
This paper addresses the problem of conducting a nonparametric test of the dimension of the state variable vector in a continuous-time term structure model. The paper shows that a bivariate diffusion function of the short rate process is a sufficient condition for the term structure to be driven by two stochastic factors. Using an easy-to-implement kernel smoothing method the number of state variables can be tested under very unrestrictive assumptions. The results suggest that continuous-time models for the US interest rates should contain at least two stochastic factors
On the robustness of the primordial power spectrum in renormalized Higgs inflation
We study the cosmological consequences of higher-dimensional operators
respecting the asymptotic symmetries of the tree-level Higgs inflation action.
The main contribution of these operators to the renormalization group enhanced
potential is localized in a compact field range, whose upper limit is close to
the end of inflation. The spectrum of primordial fluctuations in the so-called
universal regime turns out to be almost insensitive to radiative corrections
and in excellent agreement with the present cosmological data. However,
higher-dimensional operators can play an important role in critical Higgs
inflation scenarios containing a quasi-inflection point along the inflationary
trajectory. The interplay of radiative corrections with this quasi-inflection
point may translate into a sizable modification of the inflationary
observables.Comment: 12 pages, 8 figures - matches the published versio
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