Heavy Quarkonia

We review a decade of studies devoted to the physics of heavy quark bound states $cc$ and $bb$. After addressing the question of why, how and where to perform these investigations, we turn to an analysis of the spin (in-)dependent forces acting between heavy quarks. Processes involving large momentum transfer allow a determination of the coupling constant of the strong interaction. A critical evaluation is given on the possibility to accurately determine the strong coupling. For a description of hadronic transitions within heavy quarkonia non-perturbative methods have been developed. Except for one possible problem, these calculations will be shown to be in good agreement with data. Heavy quarkonia decays to light mesons provide the means to investigate known low mass states and to search for new forms of matter. Finally, an evaluation is attempted of the physics prospects which are achievable with significantly larger data sets than those available today

Statistical indentation techniques for hydrated nanocomposites: concrete, bone, and shale

International audienceConcrete, bone and shale have one thing in common: their load-bearing mineral phase is a hydrated nanocomposite. Yet the link between material genesis, microstructure, and mechanical performance for these materials is still an enigma that has deceived many decoding attempts. In this article, we advance statistical indentation analysis techniques that make it possible to assess, in situ, the nanomechanical properties, packing density distributions, and morphology of hydrated nanocomposites. These techniques are applied to identify intrinsic and structural sources of anisotropy of hydrated nanoparticles: calcium–silicate–hydrate (C–S–H), apatite, and clay. It is shown that C–S–H and apatite, the binding phase in, respectively, cement-based materials and bone, are intrinsically isotropic; this is most probably due to a random precipitation and growth process of particles in calcium oversaturated pore solutions, which can also explain the nonnegligible internanoparticle friction. In contrast, the load-bearing clay phase in shale, the sealing formation of most hydrocarbon reservoirs, is found to be intrinsically anisotropic and frictionless. This is indicative of a ‘smooth' deposition and compaction history, which, in contrast to mineral growth in confined spaces, minimizes nanoparticle interlocking. In all cases, the nanomechanical behavior is governed by packing density distributions of elementary particles delimitating macroscopic diversity

Measurement of the muonic branching fractions of the Υ(1S) and Υ(3S)

Using the CLEO detector at the Cornell Electron Storage Ring, we have measured the muonic branching fractions B of the (1S) and (3S) to be (2.520.070.07)% and (2.020.190.33)%, respectively. © 1989 The American Physical Society