53,135 research outputs found
Higgsed Gauge-flation
We study a variant of Gauge-flation where the gauge symmetry is spontaneously
broken by a Higgs sector. We work in the Stueckelberg limit and demonstrate
that the dynamics remain (catastrophically) unstable for cases where the gauge
field masses satisfy , where , is the
gauge coupling, is the gauge field vacuum expectation value, and is
the Hubble rate. We compute the spectrum of density fluctuations and
gravitational waves, and show that the model can produce observationally viable
spectra. The background gauge field texture violates parity, resulting in a
chiral gravitational wave spectrum. This arises due to an exponential
enhancement of one polarization of the spin-2 fluctuation of the gauge field.
Higgsed Gauge-flation can produce observable gravitational waves at
inflationary energy scales well below the GUT scale.Comment: 52 pages, 14 figure
On the Invalidity of Fourier Series Expansions of Fractional Order
The purpose of this short paper is to show the invalidity of a Fourier series
expansion of fractional order as derived by G. Jumarie in a series of papers.
In his work the exponential functions are replaced by the
Mittag-Leffler functions over
the interval where and
is the period of the function i.e.,
$E_\alpha \left( ix^\alpha\right)=E_\alpha \left( i(x+M_\alpha)^\alpha\right).
Exploration vs. Exploitation in the Information Filtering Problem
We consider information filtering, in which we face a stream of items too
voluminous to process by hand (e.g., scientific articles, blog posts, emails),
and must rely on a computer system to automatically filter out irrelevant
items. Such systems face the exploration vs. exploitation tradeoff, in which it
may be beneficial to present an item despite a low probability of relevance,
just to learn about future items with similar content. We present a Bayesian
sequential decision-making model of this problem, show how it may be solved to
optimality using a decomposition to a collection of two-armed bandit problems,
and show structural results for the optimal policy. We show that the resulting
method is especially useful when facing the cold start problem, i.e., when
filtering items for new users without a long history of past interactions. We
then present an application of this information filtering method to a
historical dataset from the arXiv.org repository of scientific articles.Comment: 36 pages, 5 figure
A new species of the basal araneomorph spider genus Ectatosticta (Araneae, Hypochilidae) from China
The hypochilid spider Ectatosticta davidi (Simon) is redescribed on the basis of adults from Mt. Taibaishan in Shaanxi Province, China; the specimens from Qinghai Province previously identified as E. davidi by most modern authors belong to a new species described as E. deltshevi. Keywords: Araneae, Araneomorphae, Hypochilidae, Ectatosticta, Chin
- …