559 research outputs found
F-Term Hybrid Inflation Followed by a Peccei-Quinn Phase Transition
We consider a cosmological set-up, based on renormalizable superpotential
terms, in which a superheavy scale F-term hybrid inflation is followed by a
Peccei-Quinn phase transition, resolving the strong CP and mu problems of the
minimal supersymmetric standard model. We show that the field which triggers
the Peccei-Quinn phase transition can remain after inflation well above the
Peccei-Quinn scale thanks to (i) its participation in the supergravity and
logarithmic corrections during the inflationary stage and (ii) the high reheat
temperature after the same period. As a consequence, its presence influences
drastically the inflationary dynamics and the universe suffers a second period
of reheating after the Peccei-Quinn phase transition. Confronting our
inflationary predictions with the current observational data, we find that, for
about the central value of the spectral index, the grand unification scale can
be identified with its supersymmetric value for the relevant coupling constant
\kappa=0.002 and, more or less, natural values, +/-(0.01-0.1), for the
remaining parameters. On the other hand, the final reheat temeperature after
the Peccei-Quinn phase transition turns out to be low enough so as the
gravitino problem is avoided.Comment: 15 pages including 8 figures, version published in Phys. Rev.
Shift Symmetry and Higgs Inflation in Supergravity with Observable Gravitational Waves
We demonstrate how to realize within supergravity a novel chaotic-type
inflationary scenario driven by the radial parts of a conjugate pair of Higgs
superfields causing the spontaneous breaking of a grand unified gauge symmetry
at a scale assuming the value of the supersymmetric grand unification scale.
The superpotential is uniquely determined at the renormalizable level by the
gauge symmetry and a continuous R symmetry. We select two types of Kahler
potentials, which respect these symmetries as well as an approximate shift
symmetry. In particular, they include in a logarithm a dominant shift-symmetric
term proportional to a parameter c- together with a small term violating this
symmetry and characterized by a parameter c+. In both cases, imposing a lower
bound on c-, inflation can be attained with subplanckian values of the original
inflaton, while the corresponding effective theory respects perturbative
unitarity for r+-=c+/c-<1. These inflationary models do not lead to
overproduction of cosmic defects, are largely independent of the one-loop
radiative corrections and accommodate, for natural values of r+-, observable
gravitational waves consistently with all the current observational data. The
inflaton mass is mostly confined in the range (3.7-8.1)x10^10 GeV.Comment: Final version with some typos correcte
Yukawa Quasi-Unification and Inflation
We review the construction of a concrete supersymmetric grand unified model,
which naturally leads to a moderate violation of "asymptotic" Yukawa
unification and, thus, can allow an acceptable b-quark mass within the
constrained minimal supersymmetric standard model with mu>0. The model
possesses a wide and natural range of parameters which is consistent with the
data on the cold dark matter abundance in the universe, b-->s gamma, the muon
anomalous magnetic moment and the Higgs boson masses. Also, it automatically
leads to a new version of shifted hybrid inflation, which avoids overproduction
of monopoles at the end of inflation by using only renormalizable terms.Comment: Talk presented by G. Lazarides at the BW2003 Workshop, Vrnjacka
Banja, Serbia, 29 August-2 September 2003 (to appear in the proceedings), 15
pages including 3 figures, uses ws-procs9x6.cls and rotating_pr.st
Inflation, Leptogenesis, and Yukawa Quasi-Unification within a Supersymmetric Left-Right Model
A simple extension of the minimal left-right symmetric supersymmetric grand
unified theory model is constructed by adding two pairs of superfields. This
naturally violates the partial Yukawa unification predicted by the minimal
model. After including supergravity corrections, we find that this extended
model naturally supports hilltop F-term hybrid inflation along its trivial
inflationary path with only a very mild tuning of the initial conditions. With
a convenient choice of signs of the terms in the Kahler potential, we can
reconcile the inflationary scale with the supersymmetric grand unified theory
scale. All the current data on the inflationary observables are readily
reproduced. Inflation is followed by non-thermal leptogenesis via the decay of
the right-handed neutrinos emerging from the decay of the inflaton and any
possible washout of the lepton asymmetry is avoided thanks to the violation of
partial Yukawa unification. The extra superfields also assist us in reducing
the reheat temperature so as to satisfy the gravitino constraint. The observed
baryon asymmetry of the universe is naturally reproduced consistently with the
neutrino oscillation parameters.Comment: 20 pages including 4 figure
Probing the Supersymmetry-Mass Scale With F-term Hybrid Inflation
We consider F-term hybrid inflation and supersymmetry breaking in the context
of a model which largely respects a global U(1) R symmetry. The Kaehler
potential parameterizes the Kaehler manifold with an enhanced
U(1)x(SU(1,1)/U(1)) symmetry, where the scalar curvature of the second factor
is determined by the achievement of a supersymmetry-breaking de Sitter vacuum
without ugly tuning. The magnitude of the emergent soft tadpole term for the
inflaton can be adjusted in the range (1.2-460) TeV -- increasing with the
dimensionality of the representation of the waterfall fields -- so that the
inflationary observables are in agreement with the observational requirements.
The mass scale of the supersymmetric partners turns out to lie in the region
(0.09-253) PeV which is compatible with high-scale supersymmetry and the
results of LHC on the Higgs boson mass. The mu parameter can be generated by
conveniently applying the Giudice-Masiero mechanism and assures the
out-of-equilibrium decay of the R saxion at a low reheat temperature Trh<~163
GeV
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