288 research outputs found
Reconstruction of the primordial fluctuation spectrum from the five-year WMAP data by the cosmic inversion method with band-power decorrelation analysis
The primordial curvature fluctuation spectrum is reconstructed by the cosmic
inversion method using the five-year WMAP data of the cosmic microwave
background temperature anisotropy. We apply the covariance matrix analysis and
decompose the reconstructed spectrum into statistically independent
band-powers. The statistically significant deviation from a simple power-law
spectrum suggested by the analysis of the first-year data is not found in the
five-year data except possibly at one point near the border of the wavenumber
domain where accurate reconstruction is possible.Comment: 9page
Metric perturbation from inflationary magnetic field and generic bound on inflation models
There is an observational indication of extragalactic magnetic fields. No
known astrophysical process can explain the origin of such large scale magnetic
fields, which motivates us to look for their origin in primordial inflation. By
solving the linearized Einstein equations, we study metric perturbations
sourced by magnetic fields that are produced during inflation. This leads to a
simple but robust bound on the inflation models by requiring that the induced
metric perturbation should not exceed the observed value 10^-5. In case of the
standard single field inflation model, the bound can be converted into a lower
bound on the Hubble parameter during inflation.Comment: 14 page
A Conjecture about Raising Operators for Macdonald Polynomials
A multivariable hypergeometric-type formula for raising operators of the
Macdonald polynomials is conjectured. It is proved that this agrees with Jing
and Jozefiak's expression for the two-row Macdonald polynomials, and also with
Lassalle and Schlosser's formula for partitions with length three.Comment: 13 page
Hiding cosmic strings in supergravity D-term inflation
The influence of higher-order terms in the K\"{a}hler potential of the
supergravity D-term inflation model on the density perturbation is studied. We
show that these terms can make the inflaton potential flatter, which lowers the
energy scale of inflation under the COBE/WMAP normalization. As a result, the
mass per unit length of cosmic strings, which are produced at the end of
inflation, can be reduced to a harmless but detectable level without
introducing a tiny Yukawa coupling. Our scenario can naturally be implemented
in models with a low cut-off as in Type I or Type IIB orientifold models.Comment: 15 pages, 4 figure
Cosmology Based on f(R) Gravity Admits 1 eV Sterile Neutrinos
It is shown that the tension between recent neutrino oscillation experiments,
favoring sterile neutrinos with masses of the order of 1 eV, and cosmological
data which impose stringent constraints on neutrino masses from the free
streaming suppression of density fluctuations, can be resolved in models of the
present accelerated expansion of the Universe based on f(R) gravity.Comment: 5 pages, 3 figures, matches the published version in Phys. Rev. Let
Improving the performance of dictionary-based approaches in protein name recognition
AbstractDictionary-based protein name recognition is often a first step in extracting information from biomedical documents because it can provide ID information on recognized terms. However, dictionary-based approaches present two fundamental difficulties: (1) false recognition mainly caused by short names; (2) low recall due to spelling variations. In this paper, we tackle the former problem using machine learning to filter out false positives and present two alternative methods for alleviating the latter problem of spelling variations. The first is achieved by using approximate string searching, and the second by expanding the dictionary with a probabilistic variant generator, which we propose in this paper. Experimental results using the GENIA corpus revealed that filtering using a naive Bayes classifier greatly improved precision with only a slight loss of recall, resulting in 10.8% improvement in F-measure, and dictionary expansion with the variant generator gave further 1.6% improvement and achieved an F-measure of 66.6%
Time variation of proton-electron mass ratio and fine structure constant with runaway dilaton
Recent astrophysical observations indicate that the proton-electron mass
ratio and the fine structure constant have gone through nontrivial time
evolution. We discuss their time variation in the context of a dilaton runaway
scenario with gauge coupling unification at the string scale . We
show that the choice of adjustable parameters allows them to fit the same order
magnitude of both variations and their (opposite) signs in such a scenario.Comment: 16 pages, 1 figure, to appear in Phys. Rev.
Mutual Information and Boson Radius in c=1 Critical Systems in One Dimension
We study the generic scaling properties of the mutual information between two
disjoint intervals, in a class of one-dimensional quantum critical systems
described by the c=1 bosonic field theory. A numerical analysis of a spin-chain
model reveals that the mutual information is scale-invariant and depends
directly on the boson radius. We interpret the results in terms of correlation
functions of branch-point twist fields. The present study provides a new way to
determine the boson radius, and furthermore demonstrates the power of the
mutual information to extract more refined information of conformal field
theory than the central charge.Comment: 4.1 pages, 5 figure
Thermal background can solve the cosmological moduli problem
It is shown that the coherent field oscillation of moduli fields with weak or
TeV scale masses can dissipate its energy efficiently if they have a derivative
coupling to standard bosonic fields in a thermal state. This mechanism may
provide a new solution to the cosmological moduli problem in some special
situations.Comment: 4 pages. revised versio
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