1,203 research outputs found
D-term chaotic inflation in supergravity
Even though the chaotic inflation is one of the most popular inflation models
for its simple dynamics and compelling resolutions to the initial condition
problems, its realization in supergravity has been considered a challenging
task. We discuss how the chaotic inflation dominated by the D-term can be
induced in supergravity, which would give a new perspective on the inflation
model building in supergravity.Comment: 5 pages, to appear in Phys. Rev.
Cross-correlating the Thermal Sunyaev-Zel'dovich Effect and the Distribution of Galaxy Clusters
We present the analytical formulas, derived based on the halo model, to
compute the cross-correlation between the thermal Sunyaev-Zel'dovich (SZ)
effect and the distribution of galaxy clusters. By binning the clusters
according to their redshifts and masses, this cross-correlation, the so-called
stacked SZ signal, reveals the average SZ profile around the clusters. The
stacked SZ signal is obtainable from a joint analysis of an
arcminute-resolution cosmic microwave background (CMB) experiment and an
overlapping optical survey, which allows for detection of the SZ signals for
clusters whose masses are below the individual cluster detection threshold. We
derive the error covariance matrix for measuring the stacked SZ signal, and
then forecast for its detection from ongoing and forthcoming combined
CMB-optical surveys. We find that, over a wide range of mass and redshift, the
stacked SZ signal can be detected with a significant signal to noise ratio
(total S/N \gsim 10), whose value peaks for the clusters with intermediate
masses and redshifts. Our calculation also shows that the stacking method
allows for probing the clusters' SZ profiles over a wide range of scales, even
out to projected radii as large as the virial radius, thereby providing a
promising way to study gas physics at the outskirts of galaxy clusters.Comment: 11 pages, 6 figures, 3 tables, minor revisions reflect PRD published
versio
New D-term chaotic inflation in supergravity and leptogenesis
We present a new model of D-term dominated chaotic inflation in supergravity.
The F-flat direction present in this model is lifted by the dominant D-term,
which leads to chaotic inflation and subsequent reheating. No cosmic string is
formed after inflation because the U(1) gauge symmetry is broken during
inflation. The leptogenesis scenario via the inflaton decay in our D-term
chaotic inflation scenario is also discussed.Comment: 14 pages, no figure, to appear in Phys. Rev.
Precision of Inflaton Potential Reconstruction from CMB Using the General Slow-Roll Approximation
Through a principal component analysis, we study how accurately CMB
observables can constrain inflaton potentials in a model independent manner. We
apply the general slow-roll approximation in our analysis where we allow, in
contrast to the standard slow-roll approximation, the possibility of variations
in and take into account the fact that horizon crossing is not an
instantaneous event. Our analysis provides a set of modes to be used in fitting
observables. We find that of order five of these modes will be constrained by
future observations, so a fully general data analysis package could use the
amplitudes of just a handful of modes as free parameters and retain all
relevant information in the data
Orbital-dependent modifications of electronic structure across magneto-structural transition in BaFe2As2
Laser angle-resolved photoemission spectroscopy (ARPES) is employed to
investigate the temperature (T) dependence of the electronic structure in
BaFe2As2 across the magneto-structural transition at TN ~ 140 K. A drastic
transformation in Fermi surface (FS) shape across TN is observed, as expected
by first-principles band calculations. Polarization-dependent ARPES and band
calculations consistently indicate that the observed FSs at kz ~ pi in the
low-T antiferromagnetic (AF) state are dominated by the Fe3dzx orbital, leading
to the two-fold electronic structure. These results indicate that
magneto-structural transition in BaFe2As2 accompanies orbital-dependent
modifications in the electronic structure.Comment: 13 pages, 4 figures. accepted by Physical Review Letter
The Earliest Optical Observations of GRB 030329
We present the earliest optical imaging observations of GRB 030329 related to
SN 2003dh. The burst was detected by the HETE-2 satellite at 2003 March 29,
11:37:14.67 UT. Our wide-field monitoring started 97 minutes before the trigger
and the burst position was continuously observed. We found no precursor or
contemporaneous flare brighter than () in 32 s (64 s) timescale
between 10:00 and 13:00 UT. Follow-up time series photometries started at
12:51:39 UT (75 s after position notice through the GCN) and continued for more
than 5 hours. The afterglow was at min after burst.
Its fading between 1.2 and 6.3 hours is well characterized by a single
power-law of the form in -band. No significant flux variation was
detected and upper limits are derived as % in
minutes to hours timescales and % in seconds to
minutes timescales. Such a featureless lightcurve is explained by the smooth
distribution of circumburst medium. Another explanation is that the optical
band was above the synchrotron cooling frequency where emergent flux is
insensitive to the ambient density contrasts. Extrapolation of the afterglow
lightcurve to the burst epoch excludes the presence of an additional flare
component at minutes as seen in GRB 990123 and GRB 021211.Comment: ApJL, in pres
Evaluating methods for ranking differentially expressed genes applied to microArray quality control data
<p>Abstract</p> <p>Background</p> <p>Statistical methods for ranking differentially expressed genes (DEGs) from gene expression data should be evaluated with regard to high sensitivity, specificity, and reproducibility. In our previous studies, we evaluated eight gene ranking methods applied to only Affymetrix GeneChip data. A more general evaluation that also includes other microarray platforms, such as the Agilent or Illumina systems, is desirable for determining which methods are suitable for each platform and which method has better inter-platform reproducibility.</p> <p>Results</p> <p>We compared the eight gene ranking methods using the MicroArray Quality Control (MAQC) datasets produced by five manufacturers: Affymetrix, Applied Biosystems, Agilent, GE Healthcare, and Illumina. The area under the curve (AUC) was used as a measure for both sensitivity and specificity. Although the highest AUC values can vary with the definition of "true" DEGs, the best methods were, in most cases, either the weighted average difference (WAD), rank products (RP), or intensity-based moderated <it>t </it>statistic (ibmT). The percentages of overlapping genes (POGs) across different test sites were mainly evaluated as a measure for both intra- and inter-platform reproducibility. The POG values for WAD were the highest overall, irrespective of the choice of microarray platform. The high intra- and inter-platform reproducibility of WAD was also observed at a higher biological function level.</p> <p>Conclusion</p> <p>These results for the five microarray platforms were consistent with our previous ones based on 36 real experimental datasets measured using the Affymetrix platform. Thus, recommendations made using the MAQC benchmark data might be universally applicable.</p
Palonosetron compared with ondansetron in pediatric cancer patients: multicycle analysis of a randomized Phase III study
Aim: To investigate across multiple cycles the efficacy and safety of palonosetron in the prevention of chemotherapy-induced nausea and vomiting in pediatric cancer patients receiving highly or moderately emetogenic chemotherapy (HEC/MEC). Patients & methods: Patients were randomly assigned to 10, 20 mu g/kg palonosetron or 3 x 150 mu g/kg ondansetron for up to four cycles of HEC/MEC. Results: In all on-study chemotherapy cycles, complete response rates were higher in patients in the 20 mu g/kg palonosetron group than the ondansetron group. Treatment-emergent adverse events were comparable between the palonosetron 20 mu g/kg and ondansetron groups. Conclusion: Over four cycles of HEC/MEC, 20 mu g/kg palonosetron was an efficacious and safe treatment for the prevention of chemotherapy-induced nausea and vomiting in pediatric cancer patients
Supergravity Inflation Free from Harmful Relics
We present a realistic supergravity inflation model which is free from the
overproduction of potentially dangerous relics in cosmology, namely moduli and
gravitinos which can lead to the inconsistencies with the predictions of baryon
asymmetry and nucleosynthesis. The radiative correction turns out to play a
crucial role in our analysis which raises the mass of supersymmetry breaking
field to intermediate scale. We pay a particular attention to the non-thermal
production of gravitinos using the non-minimal Kahler potential we obtained
from loop correction. This non-thermal gravitino production however is
diminished because of the relatively small scale of inflaton mass and small
amplitudes of hidden sector fields.Comment: 10 pages, revtex, 1 eps figure, references added, conclusion section
expande
Flavour constraints on scenarios with two or three heavy squark generations
We re-assess constraints from flavour-changing neutral currents in the kaon
system on supersymmetric scenarios with a light gluino, two heavy generations
of squarks and a lighter third generation. We compute for the first time limits
in scenarios with three heavy squark families, taking into account QCD
corrections at the next-to-leading order. We compare our limits with those in
the case of two heavy families. We use the mass insertion approximation and
consider contributions from gluino exchange to constrain the mixing between the
first and second squark generation. While it is not possible to perform a
general analysis, we assess the relevance of each kind of flavour- and
CP-violating parameters. We also provide ready to use magic numbers for the
computation of the Wilson coefficients at 2 GeV for these scenarios.Comment: 23 pages, 14 figures; v3: matches published version (contains
improvements in the presentation and clarifications
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