Search results for "Bay"
showing 10 items of 1187 documents
Experimental analysis of weak mixing angles between three or four quark generations
1987
New data on weak quark decays and on weak heavy quark production are used to obtain the allowed ranges of elements of the quark mixing matrix for three or four generations of sequential quarks. The analysis yields allowed ranges for the three mixing angles in the six-quark case and for the six mixing angles in the eight-quark case.
Measurements of the semileptonic decaysB¯→Dℓν¯andB¯→D*ℓν¯using a global fit toDXℓν¯final states
2009
Semileptonic (B) over bar decays to DXl (nu) over bar (l = e or mu) are selected by reconstructing D(0)l and D(+)l combinations from a sample of 230 x 10(6) Y(4S) --> B (B) over bar decays recorded with the BABAR detector at the PEP-II e(+)e(-) collider at SLAC. A global fit to these samples in a three-dimensional space of kinematic variables is used to determine the branching fractions B(B- --> D(0)l (nu) over bar = (2.34 +/- 0.03 +/- 0.13)% and B(B- --> D*(0)l (nu) over bar) = (5.40 +/- 0.02 +/- 0.21)% where the errors are statistical and systematic, respectively. The fit also determines form-factor parameters in a parametrization based on heavy quark effective theory, resulting in rho(2)…
Underlying A_4 Symmetry for the Neutrino Mass Matrix and the Quark Mixing Matrix
2002
The discrete non-Abelian symmetry $A_4$, valid at some high-energy scale, naturally leads to degenerate neutrino masses, without spoiling the hierarchy of charged-lepton masses. Realistic neutrino mass splittings and mixing angles (one of which is necessarily maximal and the other large) are then induced radiatively in the context of softly broken supersymmetry. The quark mixing matrix is also calculable in a similar way. The mixing parameter $U_{e3}$ is predicted to be imaginary, leading to maximal CP violation in neutrino oscillations. Neutrinoless double beta decay and $\tau \to \mu \gamma$ should be in the experimentally accessible range.
ISOLTRAP Mass Measurements for Weak-Interaction Studies
2005
International audience; The conserved-vector-current (CVC) hypothesis of the weak interaction and the unitarity of the Cabibbo-Kobayashi-Maskawa (CKM) matrix are two fundamental postulates of the Standard Model. While existing data on CVC supports vector current conservation, the unitarity test of the CKM matrix currently fails by more than two standard deviations. High-precision mass measurements performed with the ISOLTRAP experiment at ISOLDE/CERN provide crucial input for these fundamental studies by greatly improving our knowledge of the decay energy of super-allowed beta decays. Recent results of mass measurements on the beta emitters 18Ne, 22Mg, 34Ar, and 74Rb as pertaining to weak-i…
The Wage Curve, Once More with Feeling: Bayesian Model Averaging of Heckit Models
2018
The sensitivity of the wage curve to sample-selection and model uncertainty was evaluated with Bayesian methods. More than 8000 Heckit wage curves were estimated using data from the 2017 household survey of Bolivia. After averaging the estimates with the posterior probability of each model being true, the wage curve elasticity in Bolivia is close to -0.01. This result suggests that in this country the wage curve is inelastic and does not follow the international statistical regularity of wage curves.
Emotional stress & decision-making: an emotional stressor significantly reduces loss aversion
2021
Stress influences loss aversion, the principle that losses loom larger than gains, although the nature of this relationship is unclear. Studies show that stress reduces loss aversion; however, stress response has been only studied by means of physiological measures, but the stressor emotional impact remained unclear. Since emotions can modify stress response and increase the activity of the loss aversion neural substrates, it could be expected that an emotional stressor may produce the opposite effect, i.e. loss aversion increase. 69 participants were divided into experimental and control group. The first one was exposed to emotional stress through a 5-minutes video, and control group viewe…
Decomposing encoding and decisional components in visual-word recognition: a diffusion model analysis.
2014
In a diffusion model, performance as measured by latency and accuracy in two-choice tasks is decomposed into different parameters that can be linked to underlying cognitive processes. Although the diffusion model has been utilized to account for lexical decision data, the effects of stimulus manipulations in previous experiments originated from just one parameter: the quality of the evidence. Here we examined whether the diffusion model can be used to effectively decompose the underlying processes during visual-word recognition. We explore this issue in an experiment that features a lexical manipulation (word frequency) that we expected to affect mostly the quality of the evidence (the dri…
Do pollinator distributions underlie the evolution of pollination ecotypes in the Cape shrub Erica plukenetii?
2013
Background and aims According to the Grant-Stebbins model of pollinator-driven divergence, plants that disperse beyond the range of their specialized pollinator may adapt to a new pollination system. Although this model provides a compelling explanation for pollination ecotype formation, few studies have directly tested its validity in nature. Here we investigate the distribution and pollination biology of several subspecies of the shrub Erica plukenetii from the Cape Floristic Region in South Africa. We analyse these data in a phylogenetic context and combine these results with information on pollinator ranges to test whether the evolution of pollination ecotypes is consistent with the Gra…
Chemical speciation of metals from marine sediments : assessment of potential pollution risk while dredging, a case study in southern Sweden
2020
Abstract Contamination associated with metals is a critical concern related to their toxicity, persistence, and bio-accumulation. Trace elements are partitioned into several chemical forms, which some are more labile during fluctuations in the environment. Studying the distribution of metals between the different chemical fractions contributes to assess their bioavailability and to identify their potential risk of contamination to surrounding environments. This study concerns the speciation of metals (Pb, Cr, Ni, Zn and Fe) from sediments coming out from Malmfjarden bay, Sweden. The aim was to assess the potential risk of metal pollution during present and future dredging as well as while u…
Distribution of Heavy Metals in Marine Sediments of Palermo Gulf (Sicily, Italy)
2008
Concentrations of Cr, Cu, Hg, Pb and Zn have been measured, by atomic absorption spectrophotometry, in the fine fraction (<63 μm) of surface sediments collected in 30 sites in the Palermo Gulf (Sicily, Italy) in order to assess the levels and the spatial distribution of these elements. Enrichment factors calculated with respect to clean areas have been considered to discriminate between levels due to background or to pollution contributions. The sampling stations, which form a grid inside these areas, are characterized by geographic proximity and by the presence of pollution sources. Ratio matching technique along with hierarchical clustering, minimum spanning tree and principal component a…