9,404 research outputs found
Towards a warped inflationary brane scanning
We present a detailed systematics for comparing warped brane inflation with
the observations, incorporating the effects of both moduli stabilization and
ultraviolet bulk physics. We explicitly construct an example of the inflaton
potential governing the motion of a mobile D3 brane in the entire warped
deformed conifold. This allows us to precisely identify the corresponding
scales of the cosmic microwave background. The effects due to bulk fluxes or
localized sources are parametrized using gauge/string duality. We next perform
some sample scannings to explore the parameter space of the complete potential,
and first demonstrate that without the bulk effects there can be large
degenerate sets of parameters with observationally consistent predictions. When
the bulk perturbations are included, however, the observational predictions are
generally spoiled. For them to remain consistent, the magnitudes of the bulk
effects need to be highly suppressed via fine tuning.Comment: (v1) 11 pages, 2 figures, 2 tables; (v2) more clarifications and
references added; (v3) 12 pages, more discussions, to appear in Physical
Review
Breaking scale invariance from a singular inflaton potential
In this paper we break the scale invariance of the primordial power spectrum
of curvature perturbations of inflation. Introducing a singular behaviour due
to spontaneous symmetry breaking in the inflaton potential, we obtain fully
analytic expressions of scale dependent oscillation and a modulation in power
on small scale in the primordial spectrum. And we give the associated cosmic
microwave background and matter power spectra which we can observe now and
discuss the signature of the scale dependence. We also address the possibility
of whether some inflationary model with featured potential might mimic the
predictions of the scale invariant power spectrum. We present some examples
which illustrate such degeneracies.Comment: 20 pages, 9 figures; Discussion expanded and references added;
Miscellaneous typos correcte
Inflation in minimal left-right symmetric model with spontaneous D-parity breaking
We present a simplest inflationary scenario in the minimal left-right
symmetric model with spontaneous D-parity breaking, which is a well motivated
particle physics model for neutrino masses. This leads us to connect the
observed anisotropies in the cosmic microwave background to the sub-eV neutrino
masses. The baryon asymmetry via the leptogenesis route is also discussed
briefly.Comment: (v1) 4 pages, 1 figure; (v2) typos corrected; (v3) title and abstract
changed, numerical estimates given, minor changes; (v4) 5 pages, relations
between the neutrino masses and the CMB fluctuations become more explicit,
miscellaneous changes, to appear in Physical Review
Inflationary Hubble Parameter from the Gravitational Wave Spectrum in the General Slow-roll Approximation
Improved general slow-roll formulae giving the primordial gravitational wave
spectrum are derived in the present work. Also the first and second order
general slow-roll inverse formulae giving the Hubble parameter in terms of
the gravitational wave spectrum are derived. Moreover, the general slow-roll
consistency condition relating the scalar and tensor spectra is obtained
When is Quantum Decoherence Dynamics Classical?
A direct classical analog of quantum decoherence is introduced. Similarities
and differences between decoherence dynamics examined quantum mechanically and
classically are exposed via a second-order perturbative treatment and via a
strong decoherence theory, showing a strong dependence on the nature of the
system-environment coupling. For example, for the traditionally assumed linear
coupling, the classical and quantum results are shown to be in exact agreement.Comment: 5 pages, no figures, to appear in Physical Review Letter
Variability of Contact Process in Complex Networks
We study numerically how the structures of distinct networks influence the
epidemic dynamics in contact process. We first find that the variability
difference between homogeneous and heterogeneous networks is very narrow,
although the heterogeneous structures can induce the lighter prevalence.
Contrary to non-community networks, strong community structures can cause the
secondary outbreak of prevalence and two peaks of variability appeared.
Especially in the local community, the extraordinarily large variability in
early stage of the outbreak makes the prediction of epidemic spreading hard.
Importantly, the bridgeness plays a significant role in the predictability,
meaning the further distance of the initial seed to the bridgeness, the less
accurate the predictability is. Also, we investigate the effect of different
disease reaction mechanisms on variability, and find that the different
reaction mechanisms will result in the distinct variabilities at the end of
epidemic spreading.Comment: 6 pages, 4 figure
Non-Gaussianity from false vacuum inflation: Old curvaton scenario
We calculate the three-point correlation function of the comoving curvature
perturbation generated during an inflationary epoch driven by false vacuum
energy. We get a novel false vacuum shape bispectrum, which peaks in the
equilateral limit. Using this result, we propose a scenario which we call "old
curvaton". The shape of the resulting bispectrum lies between the local and the
false vacuum shapes. In addition we have a large running of the spectral index.Comment: 13 pages, 3 figures; v2 with minor revison; v3 final version to
appear on JCA
Deep Discrete Hashing with Self-supervised Pairwise Labels
Hashing methods have been widely used for applications of large-scale image
retrieval and classification. Non-deep hashing methods using handcrafted
features have been significantly outperformed by deep hashing methods due to
their better feature representation and end-to-end learning framework. However,
the most striking successes in deep hashing have mostly involved discriminative
models, which require labels. In this paper, we propose a novel unsupervised
deep hashing method, named Deep Discrete Hashing (DDH), for large-scale image
retrieval and classification. In the proposed framework, we address two main
problems: 1) how to directly learn discrete binary codes? 2) how to equip the
binary representation with the ability of accurate image retrieval and
classification in an unsupervised way? We resolve these problems by introducing
an intermediate variable and a loss function steering the learning process,
which is based on the neighborhood structure in the original space.
Experimental results on standard datasets (CIFAR-10, NUS-WIDE, and Oxford-17)
demonstrate that our DDH significantly outperforms existing hashing methods by
large margin in terms of~mAP for image retrieval and object recognition. Code
is available at \url{https://github.com/htconquer/ddh}
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