4,781 research outputs found
Electroweak physics at the Tevatron
We present a review of the recent Tevatron diboson measurements in leptonic and semileptonic decay modes. The most stringent limits on anomalous triple gauge couplings are reported for each final state
Observation of WW/WZ →ℓν+ jets at CDF
We present the observation of WW+WZ production in the channel with an identified lepton and two jets in 4.3 fb
−1 of integrated luminosity collected by the CDF II detector in p¯p collsions at √s = 1.96TeV. The measurement uses a fit to the dijet mass to disentagle the signal from the large background. The significance of the result is found to be 5.24σ and the cross section is measured to be
18.1±3.3(stat.)±2.5(syst.) pb, in good agreement with Standard Model prediction
Extracting Galaxy Cluster Gas Inhomogeneity from X-ray Surface Brightness: A Statistical Approach and Application to Abell 3667
Our previous analysis indicates that small-scale fluctuations in the
intracluster medium (ICM) from cosmological hydrodynamic simulations follow the
lognormal distribution. In order to test the lognormal nature of the ICM
directly against X-ray observations of galaxy clusters, we develop a method of
extracting statistical information about the three-dimensional properties of
the fluctuations from the two-dimensional X-ray surface brightness.
We first create a set of synthetic clusters with lognormal fluctuations.
Performing mock observations of these synthetic clusters, we find that the
resulting X-ray surface brightness fluctuations also follow the lognormal
distribution fairly well. Systematic analysis of the synthetic clusters
provides an empirical relation between the density fluctuations and the X-ray
surface brightness. We analyze \chandra observations of the galaxy cluster
Abell 3667, and find that its X-ray surface brightness fluctuations follow the
lognormal distribution. While the lognormal model was originally motivated by
cosmological hydrodynamic simulations, this is the first observational
confirmation of the lognormal signature in a real cluster. Finally we check the
synthetic cluster results against clusters from cosmological hydrodynamic
simulations. As a result of the complex structure exhibited by simulated
clusters, the empirical relation shows large scatter. Nevertheless we are able
to reproduce the true value of the fluctuation amplitude of simulated clusters
within a factor of two from their X-ray surface brightness alone.
Our current methodology combined with existing observational data is useful
in describing and inferring the statistical properties of the three dimensional
inhomogeneity in galaxy clusters.Comment: 34 pages, 17 figures, accepted for publication in Ap
The rhythm of effective entrepreneurs’ decision-making process. The pathways of alertness scanning and search and cognitive style. A mediation model
How can entrepreneurs be effective when making decisions? To enrich current research on entrepreneurship and cognition, the present study shows how alertness and decision making are closely related. Prompted by the scant attention that scholars have paid to the link between alertness and the pathways of entrepreneurs’ thought, it proposes that being alert by adequately scanning and searching for information is likely to increase decision-making effectiveness. Distinguishing between rational and intuitive cognitive styles and based on a sample of 98 Italian entrepreneurs from small and medium manufacturing companies, the analysis shows that while a rational cognitive style significantly mediated the relationship, intuition did not play a role in shaping entrepreneurial decision-making effectiveness. The results suggest that developing individual alertness might not be sufficient for entrepreneurs to make effective decisions; a rational cognitive style might also be a key mechanism shaping this association
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