775 research outputs found
Cosmology of Light Moduli
In string/M-theory with a large compactification radius, some axion-like
moduli can be much lighter than the gravitino. Generic moduli in gauge-mediated
supersymmetry breaking models also have a mass far below the weak scale.
Motivated by these, we examine the cosmological implications of light moduli
for the mass range from the weak scale to an extremely small scale of order
10^{-26} eV, and obtain an upper bound on the initial moduli misalignment for
both cases with and without a late entropy production.Comment: 23 pages including 3 pictex-figures, Late
Probing Higgs in Type III Seesaw at the LHC
We show that the type III seesaw mechanism opens up a promising possibility
of searching the Higgs boson in the channel through the Higgs
production associated with a charged lepton coming from the decay of the
triplet seesaw particle. In particular we look for the signals with
trileptons or same-sign dileptons to construct the Higgs and the triplet
fermion mass and calculate the reach with the integrated luminosity of 10
fb at the 14 TeV LHC.Comment: 4 pages and 8 figure
Leptogenesis origin of Dirac gaugino dark matter
The Dirac nature of the gauginos (and also the Higgsinos) can be realized in
-symmetric supersymmetry models. In this class of models, the Dirac bino (or
wino) with a small mixture of the Dirac Higgsinos is a good dark matter
candidate. When the seesaw mechanism with Higgs triplet superfields is
implemented to account for the neutrino masses and mixing, the leptogenesis
driven by the heavy triplet decay is shown to produce not only the
matter-antimatter asymmetry but also the asymmetric relic density of the Dirac
gaugino dark matter. The dark matter mass turns out to be controlled by the
Yukawa couplings of the heavy Higgs triplets, and it can be naturally at the
weak scale for a mild hierarchy of the Yukawa couplings.Comment: 9 pages. Restructured for clear presentation, corrected some errors
and typos. No change in conclusio
Diluting the inflationary axion fluctuation by a stronger QCD in the early Universe
We propose a new mechanism to suppress the axion isocurvature perturbation,
while producing the right amount of axion dark matter, within the framework of
supersymmetric axion models with the axion scale induced by supersymmetry
breaking. The mechanism involves an intermediate phase transition to generate
the Higgs \mu-parameter, before which the weak scale is comparable to the axion
scale and the resulting stronger QCD yields an axion mass heavier than the
Hubble scale over a certain period. Combined with that the Hubble-induced axion
scale during the primordial inflation is well above the intermediate axion
scale at present, the stronger QCD in the early Universe suppresses the axion
fluctuation to be small enough even when the inflationary Hubble scale
saturates the current upper bound, while generating an axion misalignment angle
of order unity.Comment: 5 pages, 1 figure; v2: discussion extended, references added, typos
correcte
Cancellation of MRI Motion Artifact in Image Plane
In this study, a new algorithm for canceling a MRI artifact due to the translational motion in image plane is described. Unlike the conventional iterative phase retrieval algorithm, in which there is no guarantee for the convergence, a direct method for estimating the motion is presented. In previous approaches, the motions in the x(read out) direction and the y(phase encoding) direction were estimated simultaneously. However, the feature of x and y directional motions are different from each other. By analyzing their features, each x and y directional motion is canceled by the different algorithms in two steps. First, it is noticed that the x directional motion corresponds to a shift of the x directional spectrum of the MRI signal, and the non-zero area of the spectrum just corresponds to the projected area of the density function on the x axis. So the motion is estimated by tracing the edges between non-zero area and zero area of the spectrum, and the x directional motion is canceled by shifting the spectrum in an reverse direction. Next, the y directional motion canceled by using a new constraint condition, with which the motion component and the true image component can be separated. This algorithm is shown to be effective by using a phantom image with simulated motion
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