528 research outputs found
Natural inflation with and without modulations in type IIB string theory
We propose a mechanism for the natural inflation with and without modulation
in the framework of type IIB string theory on toroidal orientifold or orbifold.
We explicitly construct the stabilization potential of complex structure,
dilaton and K\"ahler moduli, where one of the imaginary component of complex
structure moduli becomes light which is identified as the inflaton. The
inflaton potential is generated by the gaugino-condensation term which receives
the one-loop threshold corrections determined by the field value of complex
structure moduli and the axion decay constant of inflaton is enhanced by the
inverse of one-loop factor. We also find the threshold corrections can also
induce the modulations to the original scalar potential for the natural
inflation. Depending on these modulations, we can predict several sizes of
tensor-to-scalar ratio as well as the other cosmological observables reported
by WMAP, Planck and/or BICEP2 collaborations.Comment: 18 pages, 4 figures, Typos corrected, references and comments adde
Realistic three-generation models from SO(32) heterotic string theory
We search for realistic supersymmetric standard-like models from SO(32)
heterotic string theory on factorizable tori with multiple magnetic fluxes.
Three chiral ganerations of quarks and leptons are derived from the adjoint and
vector representations of SO(12) gauge groups embedded in SO(32) adjoint
representation. Massless spectra of our models also include Higgs fields, which
have desired Yukawa couplings to quarks and leptons at the tree-level.Comment: 29 pages, Typos corrected, references added, and Sec. 3.3 is adde
Gauge coupling unification in SO(32) heterotic string theory with magnetic fluxes
We study heterotic string theory on torus with magnetic fluxes.
Non-vanishing fluxes can lead to non-universal gauge kinetic functions for
which is the important features of
heterotic string theory in contrast to the theory. It is found
that the experimental values of gauge couplings are realized with
values of moduli fields based on the realistic models with the gauge symmetry and three chiral generations of quarks and
leptons without chiral exotics.Comment: 20 pages, 9 figure
Understanding flow characteristics from tsunami deposits at Odaka, Joban Coast, using a deep neural network (DNN) inverse model
The 2011 Tohoku-oki tsunami inundated the Joban coastal area in the Odaka region of the city of Minamisoma, up to 2818 m from the shoreline. In this study, the flow characteristics of the tsunami were reconstructed from deposits using the DNN (deep neural network) inverse model, suggesting that the tsunami inundation occurred in the Froude supercritical condition. The DNN inverse model effectively estimated the tsunami flow parameters in the Odaka region, including the maximum inundation distance, flow velocity, maximum flow depth, and sediment concentration. Despite having a few topographical anthropogenic undulations that caused the inundation height to fluctuate greatly, the reconstructed maximum flow depth and flow velocity were reasonable and close to the values reported in the field observations. The reconstructed data around the Odaka region were characterized by an extremely high velocity (12.1 m s⁻¹). This study suggests that the large fluctuation in flow depths on the Joban Coast compared with the stable flow depths in the Sendai Plain can be explained by the inundation in the supercritical flow condition
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