860 research outputs found
DAMA detection claim is still compatible with all other DM searches
We show that the annual modulation signal observed by DAMA can be reconciled
with all other negative results from dark matter searches with a conventional
halo model for particle masses around 5 to 9 GeV. We also show which particular
dark matter stream could produce the DAMA signal.Comment: Talk given at TAUP2005, Sept. 10-14 2005, Zaragoza (Spain). 3 pages,
4 figure
Cold dark matter in brane cosmology scenario
We analyze the dark matter problem in the context of brane cosmology. We
investigate the impact of the non-conventional brane cosmology on the relic
abundance of non-relativistic stable particles in high and low reheating
scenarios. We show that in case of high reheating temperature, the brane
cosmology may enhance the dark matter relic density by many order of magnitudes
and a stringent lower bound on the five dimensional scale is obtained. We also
consider low reheating temperature scenarios with chemical equilibrium and
non-equilibrium. We emphasize that in non-equilibrium case, the resulting relic
density is very small. While with equilibrium, it is increased by a factor of
O(10^2) with respect to the standard thermal production. Therefore, dark matter
particles with large cross section, which is favored by detection expirements,
can be consistent with the recent relic density observational limits.Comment: 14 pages, 1 figur
Anisotropy of the Cosmic Neutrino Background
The cosmic neutrino background (CNB) consists of low-energy relic neutrinos
which decoupled from the cosmological fluid at a redshift z ~ 10^{10}. Despite
being the second-most abundant particles in the universe, direct observation
remains a distant challenge. Based on the measured neutrino mass differences,
one species of neutrinos may still be relativistic with a thermal distribution
characterized by the temperature T ~ 1.9K. We show that the temperature
distribution on the sky is anisotropic, much like the photon background,
experiencing Sachs-Wolfe and integrated Sachs-Wolfe effects.Comment: 5 pages, 2 figures / updated references, discussion of earlier wor
A derivative, integral, and proportional features extractor for fault detection in dynamic processes
Role of spontaneous breathing trial in predicting successful extubation in premature infants
Background The ability of clinicians to predict successful extubation in mechanically ventilated premature neonates is limited. Identifying objective criteria for predicting successful extubation may reduce the incidence of failed extubation and the duration of mechanical ventilation. Objective To evaluate the validity of objective measures of lung function and spontaneous breathing trial (SBT) in predicting successful extubation among premature neonates with attempted extubations within the first 3 weeks of life. Methods Respiratory compliance (Crs) along with SBT was performed prior to elective extubations within 3 weeks of age in premature infants ≤32 weeks. Extubation was considered successful if patients remained extubated for >72 hr. Ventilator settings including mean airway pressure (MAP), set rate, and fraction of inspired oxygen (FiO 2 ) 24 hr after re‐intubation were compared with pre‐extubation settings, in patients requiring re‐intubation. Results Thirty‐nine of 49 infants (80%) were successfully extubated. Of 41 babies who passed SBT, only 5 infants failed extubation. SBT had 92% sensitivity, 50% specificity, 88% positive predictive, and 63% negative predictive value for successful extubation. Crs was comparable between infants who were successfully extubated and those who were not. Conclusions A SBT prior to extubation may be a practical objective adjunct in predicting successful extubation in ventilated premature infants. Pediatr Pulmonol. 2013; 48:443–448. © 2012 Wiley Periodicals, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/97465/1/22623_ftp.pd
Bounds on Relic Neutrino Masses in the Z-burst Model
Neutrinos from far-away sources annihilating at the Z resonance on relic
neutrinos may give origin to the extreme-energy cosmic rays (EECR). If
``Z-bursts'' are responsible for the EECR events, then we show that the
non-observation of cosmic ray events at energies above 2 x 10^20 eV by the
AGASA Collaboration implies a lower bound around 0.3 eV on the relic neutrino
mass. Since this mass exceeds the mass-squared differences inferred from
oscillation physics, the bound in fact applies to all three neutrino masses.
Together with the upper bound provided by comparisons of the CMB anisotropy
with large-scale structure, this bound leaves only a small interval for
neutrino masses around 0.3 eV, if Z-bursts are to explain the existing EECR
events.Comment: 19 pages, including 4 figure
Measurement of the gluon PDF at small x with neutrino telescopes
We analyze the possibility that neutrino telescopes may provide an
experimental determination of the slope lambda of the gluon distribution in the
proton at momentum fractions x smaller than the accelerator reach. The method
is based on a linear relation between lambda and the spectral index (slope) of
the down-going atmospheric muon flux above 100 TeV, for which there is no
background. Considering the uncertainties in the charm production cross section
and in the cosmic ray composition, we estimate the error on the measurement of
lambda through this method, excluding the experimental error of the telescopes,
to be ~ +/- 0.2Comment: 16 pages with 16 figures - new version, comments added, same results
and figure
Gravitational wave signatures from discrete flavor symmetries
Non-Abelian discrete symmetries have been widely used to explain the patterns of lepton masses and flavor mixing. In these models, a given symmetry is assumed at a high scale and then is spontaneously broken by scalars (the flavons), which acquire vacuum expectation values. Typically, the resulting leading order predictions for the oscillation parameters require corrections in order to comply with neutrino oscillation data. We introduce such corrections through an explicit small breaking of the symmetry. This has the advantage of solving the cosmological problems of these models without resorting to inflation. The explicit breaking induces an energy difference or "bias"between different vacua and drives the evolution of the domain walls, unavoidably produced after the symmetry breaking, towards their annihilation. Importantly, the wall annihilation leads to gravitational waves which may be observed in current and/or future experiments. We show that a distinctive pattern of gravitational waves with multiple overlapped peaks is generated when walls annihilate, which is within the reach of future detectors. We also show that cosmic walls from discrete flavor symmetries can be cosmologically safe for any spontaneous breaking scale between 1 and 1018 GeV, if the bias is chosen adequately, without the need to inflate the walls away. We use as an example a particular A4 model in which an explicit breaking is included in right-handed neutrino mass terms
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