47 research outputs found

    Dynamical Dark Energy model parameters with or without massive neutrinos

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    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?

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    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

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    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

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    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

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    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

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    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

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    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

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    The resonant substructures of B0D0π+πB^0 \to \overline{D}^0 \pi^+\pi^- decays are studied with the Dalitz plot technique. In this study a data sample corresponding to an integrated luminosity of 3.0 fb1^{-1} of pppp collisions collected by the LHCb detector is used. The branching fraction of the B0D0π+πB^0 \to \overline{D}^0 \pi^+\pi^- decay in the region m(D0π±)>2.1m(\overline{D}^0\pi^{\pm})>2.1 GeV/c2/c^2 is measured to be (8.46±0.14±0.29±0.40)×104(8.46 \pm 0.14 \pm 0.29 \pm 0.40) \times 10^{-4}, where the first uncertainty is statistical, the second is systematic and the last arises from the normalisation channel B0D(2010)π+B^0 \to D^*(2010)^-\pi^+. The π+π\pi^+\pi^- 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 m(D0π)2.8m(\overline{D}^0\pi^-) \approx 2.8 GeV/c2/c^{2} is confirmed and its spin-parity is determined for the first time as JP=3J^P = 3^-. The branching fraction, mass and width of this structure are determined together with those of the D0(2400)D^*_0(2400)^- and D2(2460)D^*_2(2460)^- resonances. The branching fractions of other B0D0h0B^0 \to \overline{D}^0 h^0 decay components with h0π+πh^0 \to \pi^+\pi^- are also reported. Many of these branching fraction measurements are the most precise to date. The first observation of the decays B0D0f0(500)B^0 \to \overline{D}^0 f_0(500), B0D0f0(980)B^0 \to \overline{D}^0 f_0(980), B0D0ρ(1450)B^0 \to \overline{D}^0 \rho(1450), B0D3(2760)π+B^0 \to D_3^*(2760)^- \pi^+ and the first evidence of B0D0f0(2020)B^0 \to \overline{D}^0 f_0(2020) 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.

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    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
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