278 research outputs found
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
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
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
Native Birdlife in Hawkeâs Bay: application of the river values assessment system (RiVAS and RiVAS+)
This report presents an application of the River Values Assessment System for existing value (RiVAS) and for potential value (RiVAS+) to native birdlife in the Hawkes Bay Region. A workshop was held in Napier on 3rd October 2011 to apply the method. This Hawkes Bay Region bird report needs to be read in conjunction with the method and with the first native bird application reports (see Hughey et al. 2010 and Gaze et al. 2010).Ministry of Science and Information, and Hawkes Bay Regional Counci
On the Moduli Problem and Baryogenesis in Gauge-mediated SUSY Breaking Models
We investigate whether the Affleck-Dine mechanism can produce sufficient
baryon number of the universe in the gauge-mediated SUSY breaking models, while
evading the cosmological moduli problem by late-time entropy production. We
find that the Q-ball formation renders the scenario very difficult to work,
irrespective of the detail mechanism of the entropy production.Comment: 11 pages, RevTeX, 5 postscript figures include
Efficient upconversion of sub-THz radiation in a high-Q whispering gallery resonator
We demonstrate efficient upconversion of sub-THz radiation into the optical
domain in a high-Q whispering gallery mode resonator with quadratic optical
nonlinearity. The 5x10^{-3} power conversion efficiency of continuous wave
100GHz signal is achieved with only 16 mW of optical pump.Comment: This revision is limited to discussion of only optical WGMs coupled
with the external Rf field. Discussion of RF WGMs is now posted separatel
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