47 research outputs found
Dynamical Dark Energy model parameters with or without massive neutrinos
We use WMAP5 and other cosmological data to constrain model parameters in
quintessence cosmologies, focusing also on their shift when we allow for
non-vanishing neutrino masses. The Ratra-Peebles (RP) and SUGRA potentials are
used here, as examples of slowly or fastly varying state parameter w(a). Both
potentials depend on an energy scale \Lambda. Here we confirm the results of
previous analysis with WMAP3 data on the upper limits on \Lambda, which turn
out to be rather small (down to ~10^{-9} in RP cosmologies and ~10^{-5} for
SUGRA). Our constraints on \Lambda are not heavily affected by the inclusion of
neutrino mass as a free parameter. On the contrary, when the neutrino mass
degree of freedom is opened, significant shifts in the best-fit values of other
parameters occur.Comment: 9 pages, 3 figures, submitted to JCA
Do WMAP data favor neutrino mass and a coupling between Cold Dark Matter and Dark Energy?
Within the frame of cosmologies where Dark Energy (DE) is a self--interacting
scalar field, we allow for a CDM--DE coupling and non--zero neutrino masses,
simultaneously. In their 0--0 version, i.e. in the absence of coupling and
neutrino mass, these cosmologies provide an excellent fit to WMAP, SNIa and
deep galaxy sample spectra, at least as good as \LambdaCDM. When the new
degrees of freedom are open, we find that CDM--DE coupling and significant
neutrino masses (~0.1eV per \nu species) are at least as likely as the 0--0
option and, in some cases, even statistically favoured. Results are obtained by
using a Monte Carlo Markov Chain approach.Comment: 18 pages, 10 figures, submitted to JCA
Robust Neutrino Constraints by Combining Low Redshift Observations with the CMB
We illustrate how recently improved low-redshift cosmological measurements
can tighten constraints on neutrino properties. In particular we examine the
impact of the assumed cosmological model on the constraints. We first consider
the new HST H0 = 74.2 +/- 3.6 measurement by Riess et al. (2009) and the
sigma8*(Omegam/0.25)^0.41 = 0.832 +/- 0.033 constraint from Rozo et al. (2009)
derived from the SDSS maxBCG Cluster Catalog. In a Lambda CDM model and when
combined with WMAP5 constraints, these low-redshift measurements constrain sum
mnu<0.4 eV at the 95% confidence level. This bound does not relax when allowing
for the running of the spectral index or for primordial tensor perturbations.
When adding also Supernovae and BAO constraints, we obtain a 95% upper limit of
sum mnu<0.3 eV. We test the sensitivity of the neutrino mass constraint to the
assumed expansion history by both allowing a dark energy equation of state
parameter w to vary, and by studying a model with coupling between dark energy
and dark matter, which allows for variation in w, Omegak, and dark coupling
strength xi. When combining CMB, H0, and the SDSS LRG halo power spectrum from
Reid et al. 2009, we find that in this very general model, sum mnu < 0.51 eV
with 95% confidence. If we allow the number of relativistic species Nrel to
vary in a Lambda CDM model with sum mnu = 0, we find Nrel =
3.76^{+0.63}_{-0.68} (^{+1.38}_{-1.21}) for the 68% and 95% confidence
intervals. We also report prior-independent constraints, which are in excellent
agreement with the Bayesian constraints.Comment: 19 pages, 6 figures, submitted to JCAP; v2: accepted version. Added
section on profile likelihood for Nrel, improved plot
Optical Light Curves of Supernovae
Photometry is the most easily acquired information about supernovae. The
light curves constructed from regular imaging provide signatures not only for
the energy input, the radiation escape, the local environment and the
progenitor stars, but also for the intervening dust. They are the main tool for
the use of supernovae as distance indicators through the determination of the
luminosity. The light curve of SN 1987A still is the richest and longest
observed example for a core-collapse supernova. Despite the peculiar nature of
this object, as explosion of a blue supergiant, it displayed all the
characteristics of Type II supernovae. The light curves of Type Ib/c supernovae
are more homogeneous, but still display the signatures of explosions in massive
stars, among them early interaction with their circumstellar material. Wrinkles
in the near-uniform appearance of thermonuclear (Type Ia) supernovae have
emerged during the past decade. Subtle differences have been observed
especially at near-infrared wavelengths. Interestingly, the light curve shapes
appear to correlate with a variety of other characteristics of these
supernovae. The construction of bolometric light curves provides the most
direct link to theoretical predictions and can yield sorely needed constraints
for the models. First steps in this direction have been already made.Comment: To be published in:"Supernovae and Gamma Ray Bursters", Lecture Notes
in Physics (http://link.springer.de/series/lnpp
First observation and amplitude analysis of the B- -> D+K-pi(-) decay
The B-→D+K-π- decay is observed in a data sample corresponding to 3.0 fb-1 of pp collision data recorded by the LHCb experiment during 2011 and 2012. Its branching fraction is measured to be B(B-→D+K-π-)=(7.31±0.19±0.22±0.39)×10-5 where the uncertainties are statistical, systematic and from the branching fraction of the normalization channel B-→D+π-π-, respectively. An amplitude analysis of the resonant structure of the B-→D+K-π- decay is used to measure the contributions from quasi-two-body B-→D0∗(2400)0K-, B-→D2∗(2460)0K-, and B-→DJ∗(2760)0K- decays, as well as from nonresonant sources. The DJ∗(2760)0 resonance is determined to have spin 1
First observation and amplitude analysis of the B−→D+K−π− decay
The B−→D+K−π− decay is observed in a data sample corresponding to 3.0 fb−1 of pp collision data recorded by the LHCb experiment during 2011 and 2012. Its branching fraction is measured to be B(B−→D+K−π−)=(7.31±0.19±0.22±0.39)×10−5 where the uncertainties are statistical, systematic and from the branching fraction of the normalization channel B−→D+π−π−, respectively. An amplitude analysis of the resonant structure of the B−→D+K−π− decay is used to measure the contributions from quasi-two-body B−→D∗0(2400)0K−, B−→D∗2(2460)0K−, and B−→D∗J(2760)0K− decays, as well as from nonresonant sources. The D∗J(2760)0 resonance is determined to have spin 1
New insights into the genetic etiology of Alzheimer's disease and related dementias
Characterization of the genetic landscape of Alzheimer's disease (AD) and related dementias (ADD) provides a unique opportunity for a better understanding of the associated pathophysiological processes. We performed a two-stage genome-wide association study totaling 111,326 clinically diagnosed/'proxy' AD cases and 677,663 controls. We found 75 risk loci, of which 42 were new at the time of analysis. Pathway enrichment analyses confirmed the involvement of amyloid/tau pathways and highlighted microglia implication. Gene prioritization in the new loci identified 31 genes that were suggestive of new genetically associated processes, including the tumor necrosis factor alpha pathway through the linear ubiquitin chain assembly complex. We also built a new genetic risk score associated with the risk of future AD/dementia or progression from mild cognitive impairment to AD/dementia. The improvement in prediction led to a 1.6- to 1.9-fold increase in AD risk from the lowest to the highest decile, in addition to effects of age and the APOE ε4 allele
Dalitz plot analysis ofB0→D¯0π+π−decays
The resonant substructures of decays are
studied with the Dalitz plot technique. In this study a data sample
corresponding to an integrated luminosity of 3.0 fb of collisions
collected by the LHCb detector is used. The branching fraction of the decay in the region
GeV is measured to be ,
where the first uncertainty is statistical, the second is systematic and the
last arises from the normalisation channel . The
S-wave components are modelled with the Isobar and K-matrix
formalisms. Results of the Dalitz plot analyses using both models are
presented. A resonant structure at
GeV is confirmed and its spin-parity is determined for the first time
as . The branching fraction, mass and width of this structure are
determined together with those of the and
resonances. The branching fractions of other decay
components with are also reported. Many of these branching
fraction measurements are the most precise to date. The first observation of
the decays , , ,
and the first evidence of are presented.Comment: 64 pages, 17 figure
The efficiency of sperm washing in removing human immunodeficiency virus type 1 varies according to the seminal viral load.
We evaluated the relationship between the seminal HIV-1 viral load and the efficiency of a standardized
sperm-washing procedure in removing HIV-1 RNA from semen samples. The results obtained indicate that the
amount of virus present in the original sample affects the efficiency of the procedure and suggest that the seminal
viral load should be preevaluated before enrolling an HIV-serodiscordant couple in an assisted reproduction
protocol