3,023 research outputs found
511 keV Gamma Ray from Moduli Decay in the Galactic Bulge
We show that the decay of a light scalar boson of mass 1-10 MeV may
account for the fluxes of 511 keV gamma ray observed by SPI/INTEGRAL. We argue
that candidates of such a light scalar boson is one of the string moduli or a
scalar partner of the axion in a supersymmetric theory.Comment: 6 pages, no figure, we have added an appendix to describe the
dilution of the moduli by the thermal inflation and some minor correction
R-Invariant Topological Inflation
We propose a topological inflation model in the framework of supergravity
with invariance. This topological inflation model is not only free from the
initial value problem of the inflaton field but also gives low reheating
temperature which is favored in supergravity since the overproduction of
gravitinos is avoided. Furthermore, the predicted spectrum of the density
fluctuations is generally tilted, which will be tested by future observations
on CMB anisotropies and large scale structure of the universe.Comment: 7pages (RevTeX file
Verifiable Radiative Seesaw Mechanism of Neutrino Mass and Dark Matter
A minimal extension of the Standard Model is proposed, where the observed
left-handed neutrinos obtain naturally small Majorana masses from a one-loop
radiative seesaw mechanism. This model has two candidates (one bosonic and one
fermionic) for the dark matter of the Universe. It has a very simple structure
and should be verifiable in forthcoming experiments at the Large Hadron
Collider.Comment: 8 pages, 1 figur
Connection Between the Neutrino Seesaw Mechanism and Properties of the Majorana Neutrino Mass Matrix
If it can be ascertained experimentally that the 3X3 Majorana neutrino mass
matrix M_nu has vanishing determinants for one or more of its 2X2 submatrices,
it may be interpreted as supporting evidence for the theoretically well-known
canonical seesaw mechanism. I show how these two things are connected and offer
a realistic M_nu with two zero subdeterminants as an example.Comment: title changed, version to appear in PRD(RC
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
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