196 research outputs found
Spectrum of Background X-rays from Moduli Dark Matter
We examine the -ray spectrum from the decay of the dark-matter moduli with
mass keV, in particular, paying attention to the line
spectrum from the moduli trapped in the halo of our galaxy. It is found that
with the energy resolution of the current experiments (%) the line
intensity is about twice stronger than that of the continuum spectrum from the
moduli that spread in the whole universe. Therefore, in the future experiments
with higher energy resolutions it may be possible to detect such line photons.
We also investigate the -ray spectrum emitted from the decay of the
multi-GeV moduli. It is shown that the emitted photons may form MeV-bump in the
-ray spectrum. We also find that if the modulus mass is of the order of
10 GeV, the emitted photons at the peak of the continuum spectrum loses their
energy by the scattering and the shape of the spectrum is significantly
changed, which makes the constraint weaker than that obtained in the previous
works.Comment: 14 pages (RevTeX file) including four postscript figures, reviced
version to be published in Physical Review
Decreased postoperative nausea and vomiting with dexmedetomidine after off-pump coronary artery bypass grafting
Multiple D-branes as a D-brane
From BFSS matrix theory considerations, it is expected that a single
D-brane action can be obtained from N D-brane action in large N
limit. We examine and confirm this expectation by working out the details of
DBI and Chern-Simons terms of D-brane action from D-brane action.
We show that the same relation works for non-BPS, as well as BPS branesComment: 14 page
Cosmological Moduli Problem in Gauge-mediated Supersymmetry Breaking Theories
A generic class of string theories predicts the existence of light moduli
fields, and they are expected to have masses comparable to the
gravitino mass which is in a range of keV--1GeV in
gauge-mediated supersymmetry breaking theories. Such light fields with weak
interactions suppressed by the Planck scale can not avoid some stringent
cosmological constraints, that is, they suffer from `cosmological moduli
problems'. We show that all the gravitino mass region keV 1GeV is excluded by the constraints even if we incorporate a
late-time mini-inflation (thermal inflation). However, a modification of the
original thermal inflation model enables the region keV 500keV to survive the constraints. It is also stressed that
the moduli can be dark matter in our universe for the mass region keV
100keV.Comment: A few changes in section IV and
Cosmological Constraint on the String Dilaton in Gauge-mediated Supersymmetry Breaking Theories
The dilaton field in string theories (if exists) is expected to have a mass
of the order of the gravitino mass which is in a range of
keV--1GeV in gauge-mediated supersymmetry breaking models. If it is
the case, the cosmic energy density of coherent dilaton oscillation easily
exceeds the critical density of the present universe. We show that even if this
problem is solved by a late-time entropy production (thermal inflation) a
stringent constraint on the energy density of the dilaton oscillation is
derived from experimental upperbounds on the cosmic X()-ray
backgrounds. This excludes an interesting mass region, , in gauge-mediated supersymmetry breaking models.Comment: 13 pages (RevTex file including one figure, use psfig), revised
version to be published in Physical Review Letter
Strong CP and Mu Problems in Theories with Gauge Mediated Supersymmetry Breaking
We provide a simple solution to the and strong CP problems in the
context of gauge mediated supersymmetry breaking. The generic appearance of R
symmetry in dynamical supersymmetry breaking is used to implement Peccei-Quinn
symmetry. Acceptable and terms as well as the large symmetry breaking
scale are induced in the presence of nonrenormalizable interactions.
Cosmological consequences of this scheme turn out to yield constraints on the
PQ symmetry breaking scale and the number of the messenger/heavy quarks.
Complexity in introducing non-R Peccei-Quinn symmetry is contrasted with the
case of R symmetry.Comment: 10 pages, Revtex. Significantly modified version to apear in Phys.
Rev.
Adjoint Messengers and Perturbative Unification at the String Scale
We consider states in the adjoint representation of the Standard Model gauge
group as messengers for mediation of supersymmetry (SUSY) breaking. These new
messengers can shift the gauge coupling unification to the string scale at
O(5x10^{17} GeV) if their masses are at O(10^{14} GeV). The predicted SUSY mass
spectrum at the electroweak scale is significantly different from those in
other gauge-mediated or supergravity models, resulting in robust mass
relations. The gravitino mass is predicted to be about 1-10 GeV. The heavy
messenger sector could provide a superheavy dark matter candidate.Comment: 9 pages, 2 figure
Cosmological Moduli Problem and Thermal Inflation Models
In superstring theories, there exist various dilaton and modulus fields which
masses are expected to be of the order of the gravitino mass . These
fields lead to serious cosmological difficulties, so called ``cosmological
moduli problem'', because a large number of moduli particles are produced as
the coherent oscillations after the primordial inflation. We make a
comprehensive study whether the thermal inflation can solve the cosmological
moduli problem in the whole modulus mass region
predicted by both hidden sector supersymmetry (SUSY) breaking and
gauge-mediated SUSY breaking models. In particular, we take into account the
primordial inflation model whose reheating temperature is so low that its
reheating process finishes after the thermal inflation ends. We find that the
above mass region survives from
various cosmological constraints in the presence of the thermal inflation.Comment: 49 pages, 17 figure
Inflationary models with a flat potential enforced by non-abelian discrete gauge symmetries
Non-abelian discrete gauge symmetries can provide the inflaton with a flat
potential even when one takes into account gravitational strength effects. The
discreteness of the symmetries also provide special field values where
inflation can end via a hybrid type mechanism. An interesting feature of this
method is that it can naturally lead to extremely flat potentials and so, in
principle, to inflation at unusually low energy scales. Two examples of
effective field theories with this mechanism are given, one with a hybrid exit
and one with a mutated hybrid exit. They include an explicit example in which
the single field consistency condition is violated.Comment: 24 pages, uses revtex.sty, submitted to PRD (Nov. 1999) Final version
to appear in PRD. Background information on supergravity expande
Hadronic Axion Model in Gauge-Mediated Supersymmetry Breaking and Cosmology of Saxion
Recently we have proposed a simple hadronic axion model within gauge-mediated
supersymmetry breaking. In this paper we discuss various cosmological
consequences of the model in great detail. A particular attention is paid to a
saxion, a scalar partner of an axion, which is produced as a coherent
oscillation in the early universe. We show that our model is cosmologically
viable, if the reheating temperature of inflation is sufficiently low. We also
discuss the late decay of the saxion which gives a preferable power spectrum of
the density fluctuation in the standard cold dark matter model when compared
with the observation.Comment: 24 pages, 3 figure
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