52 research outputs found
Continuous Spectrum on Cosmological Collider
We study the effects of a massive field with a continuous spectrum (continuum
isocurvaton) on the inflationary bispectrum in the squeezed limit. As a
concrete example, we extend the quasi-single field inflation model to include a
continuum isocurvaton with a well-motivated spectral density from extra
dimensions and focus on a contribution to the bispectrum with a single
continuum isocurvaton exchange. In contrast to the usual case without the
continuous spectrum, the amplitude of the bispectrum has a damping feature in
the deep squeezed limit, which can be strong evidence for the continuous
spectrum.Comment: 23 pages, 3 figures; v2: references added, to be published in Journal
of Cosmology and Astroparticle Physic
Full diffeomorphism and Lorentz invariance in 4D superfield description of 6D SUGRA
We complete the four-dimensional superfield description of
six-dimensional supergravity. The missing ingredients in the previous works are
the superfields that contain the sechsbein ,
, ,
and the second gravitino. They are necessary to
make the action invariant under the diffeomorphisms and the Lorentz
transformations involving the extra dimensions. We find the corresponding
superfield transformation laws, and show the invariance of the action under
them. We also check that the resultant action reproduces the known superfield
description of five-dimensional supergravity through the dimensional reduction.Comment: 45 pages, some comments adde
Illustrating SUSY breaking effects on various inflation mechanisms
We consider the supersymmetry breaking effects on typical inflation models
with different types of K\"ahler potential. The critical size of
supersymmetry-breaking scale, above which the flatness of the inflaton
potential is spoiled, drastically changes model by model. We present the
universal description of such effects in terms of a field-dependent scaling
factor by which gravity-mediated supersymmetry breaking terms are suppressed or
enhanced, based on the conformal supergravity framework. Such a description
would be useful when we estimate them in constructing supersymmetric models of
particle cosmology.Comment: 20pages, 3 figures, v2: a reference added, v3: Appendix B adde
On the Weyl gravity extension of Higgs inflation
We consider the embedding of Higgs inflation with a non-minimal coupling into
the Weyl gravity. In this model, the effective current-current interactions
from the heavy Weyl gauge field cancel the non-canonical Higgs kinetic term in
Einstein frame, so the unitarity problem of the original Higgs inflation
becomes less severe. For a simple case where the couplings of the heavy Weyl
gauge field appears from the non-minimal couplings to the Ricci curvature
scalar in Weyl gravity, we find that the resultant model for Higgs inflation is
the same as in the Palatini formulation for Higgs inflation. The crucial
difference of our model from the Palatini formulation for Higgs inflation is
that there is a light Weyl gauge field coupled to the Higgs fields. We also
generalize the unitarization of Higgs inflation with general covariant kinetic
terms for the dilaton and the Higgs fields, and realize a successful Higgs
inflation, interpolating between the Palatini formulation for Higgs inflation
and a Higgs-like inflation. We also discuss the Higgs mechanism for the light
Weyl gauge field with an extra singlet scalar and show some interesting
signatures for Higgs physics, such as the overall suppression of Higgs
couplings and the decay of the light Weyl gauge field into a pair of Higgs
bosons.Comment: 24 pages, 1 figur
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