20 research outputs found
Inverted Hybrid Inflation as a solution to gravitino problems in Gravity Mediation
It was recently found that the decay of inflaton and the SUSY breaking field
produces many gravitinos in the gravity mediation scenario. These discoveries
led to an exclusion of many inflation models such as chaotic, (smooth) hybrid,
topological and new inflation models. Under these circumstances we searched for
a successful inflation model and found that the ``inverted'' hybrid inflation
models can solve the gravitino overproduction problem by their distinctive
shape of the potential. Furthermore, we found that this inflation model
simultaneously can explain the observed baryon asymmetry through the
non-thermal leptogenesis and is consistent with the WMAP results, that is,
and the negligible tensor to scalar ratio.Comment: 23 pages, 2 figures in
R-invariant New Inflation Model vs Supersymmetric Standard Model
We revisit the implications of the R-invariant New Inflation model to the
supersymmetric standard model in light of recent discussion of gravitino
production processes by the decay of the inflaton or the supersymmetry breaking
field. We show that the models with supergravity mediation do not go well with
the R-invariant New Inflation model, where the gravitino abundance produced by
the decay of the inflaton or the supersymmetry breaking field significantly
exceeds the bounds from cosmological observations without fine-tuning. We also
show that the models with gauge mediation can go together with R-invariant New
Inflation model, where the dark matter and the baryon asymmetry are
consistently explained without severe fine-tuning.Comment: 19 pages, 3 figure
Minimal Supergravity, Inflation, and All That
We consider an inflationary model in the hidden-sector broken supergravity
with an effectively large cutoff. The inflaton decay into right-handed
neutrinos naturally causes the observed baryon asymmetry of the universe with a
reheating temperature low enough to avoid the gravitino overproduction. We
emphasize that all the phenomenological requirements from cosmology and
particle physics are satisfied in the large-cutoff theory.Comment: 15pages, 4figures, text and refs. adde
Recommended from our members
R-invariant New Inflation Model vs Supersymetric Standard Model
We revisit the implications of the R-invariant New Inflation model to the supersymmetric standard model in light of recent discussion of gravitino production processes by the decay of the inflaton or the supersymmetry breaking field. We show that the models with supergravity mediation do not go well with the R-invariant New Inflation model, where the gravitino abundance produced by the decay of the inflaton or the supersymmetry breaking field significantly exceeds the bounds from cosmological observations without fine-tuning. We also show that the models with gauge mediation can go together with R-invariant New Inflation model, where the dark matter and the baryon asymmetry are consistently explained without severe fine-tuning
A New Inflation Model with Anomaly-mediated Supersymmetry Breaking
If there are a large number of vacua, multi-inflation may be a more mediocre
phenomenon rather than a single inflation. In the multi-inflation scenario, new
inflation is most likely the last inflation, since its energy scale is
naturally low. Furthermore, it may explain the observed spectral index of the
cosmic microwave background radiations. We show, in this letter, that a new
inflation model proposed in supergravity accounts for all the present
observations assuming anomaly mediation of supersymmetry breaking. As a result,
we find that the relic density of the winos is consistent with the observed
dark matter density in a wide range of the wino mass, 100 GeV lsim m_{tilde{w}}
lsim 2 TeV, albeit for a low reheating temperature T_{R} simeq 10^{6-7},GeV.Comment: 14 pages, 4 figures, the title is correcte
Solutions to large B and L breaking in the Randall-Sundrum model
The stability of proton and neutrino masses are discussed in the
Randall-Sundrum model. We show that relevant operators should be suppressed, if
the hierarchical Yukawa matrices are explained only by configurations of
wavefunctions for fermions and the Higgs field along the extra dimension. We
assume a discrete gauge symmetry to suppress those operators. In the
Dirac neutrino case, there is an infinite number of symmetries which may forbid
the dangerous operators. In the Majorana neutrino case, the discrete gauge
symmetries should originate from gauge symmetries which are broken on
the Planck brane. We also comment on the oscillation as a
phenomenon which can distinguish those discrete gauge symmetries.Comment: 12 pages, No figures, Added reference
The Polonyi Problem and Upper bound on Inflation Scale in Supergravity
We reconsider the Polonyi problem in gravity-mediation models for
supersymmetry (SUSY) breaking. It has been argued that there is no problem in
the dynamical SUSY breaking scenarios, since the Polonyi field acquires a
sufficiently large mass of the order of the dynamical SUSY-breaking scale
Lamada_{SUSY}. However, we find that a linear term of the Polonyi field in the
Kahler potential brings us back to the Polonyi problem, unless the inflation
scale is sufficiently low, H_{inf} < 10^{8} GeV, or the reheating temperature
is extremely low, T_{R} < 100 GeV. Here, this Polonyi problem is more serious
than the original one, since the Polonyi field mainly decays into a pair of
gravitinos.Comment: 17 pages, 1 figure, minor corrections, published versio