Measurement of the Bottom-Strange Meson Mixing Phase in the Full CDF Data Set

We report a measurement of the bottom-strange meson mixing phase \beta_s using the time evolution of B0_s -> J/\psi (->\mu+\mu-) \phi (-> K+ K-) decays in which the quark-flavor content of the bottom-strange meson is identified at production. This measurement uses the full data set of proton-antiproton collisions at sqrt(s)= 1.96 TeV collected by the Collider Detector experiment at the Fermilab Tevatron, corresponding to 9.6 fb-1 of integrated luminosity. We report confidence regions in the two-dimensional space of \beta_s and the B0_s decay-width difference \Delta\Gamma_s, and measure \beta_s in [-\pi/2, -1.51] U [-0.06, 0.30] U [1.26, \pi/2] at the 68% confidence level, in agreement with the standard model expectation. Assuming the standard model value of \beta_s, we also determine \Delta\Gamma_s = 0.068 +- 0.026 (stat) +- 0.009 (syst) ps-1 and the mean B0_s lifetime, \tau_s = 1.528 +- 0.019 (stat) +- 0.009 (syst) ps, which are consistent and competitive with determinations by other experiments.Comment: 8 pages, 2 figures, Phys. Rev. Lett 109, 171802 (2012

The systemic approach to technological education: effects of transferred learning in resolving a physics problem

International audienceno abstrac

Teachers’ Resource Systems: Their Constitution, Structure and Evolution

International audienc

Enhancing Conceptual Change in Preschool Children's Representations of Light: A Sociocognitive Approach

The aim of this study is to investigate the effect of a sociocognitive teaching strategy on young children's understanding of light. It explores their understanding of the concept of light as an entity that is transmitted independently of the light source and the final receiver. The study was conducted in three phases: pretest, teaching intervention, and post-tests. The sample consisted of 170 preschool children who were assigned to two groups. The children in the first group participated in activities which adopted a sociocognitive approach. In the context of this approach, a familiar metaphor was introduced in order to facilitate children to construct a "precursor model" about light. The children in the second group participated in activities with the same teaching objectives, but adopting an empiricist perspective. Statistical analysis using the Mann-Whitney U test indicated that the cognitive progress of the sociocognitive group was more significant than the progress of the empiricist group. This provides evidence for the effect of the sociocognitive strategy on enhancing children in constructing a "precursor model" for the concept of light. © 2013 Springer Science+Business Media Dordrecht