Heavy quarkonium: progress, puzzles, and opportunities

A golden age for heavy quarkonium physics dawned a decade ago, initiated by the confluence of exciting advances in quantum chromodynamics (QCD) and an explosion of related experimental activity. The early years of this period were chronicled in the Quarkonium Working Group (QWG) CERN Yellow Report (YR) in 2004, which presented a comprehensive review of the status of the field at that time and provided specific recommendations for further progress. However, the broad spectrum of subsequent breakthroughs, surprises, and continuing puzzles could only be partially anticipated. Since the release of the YR, the BESII program concluded only to give birth to BESIII; the $B$-factories and CLEO-c flourished; quarkonium production and polarization measurements at HERA and the Tevatron matured; and heavy-ion collisions at RHIC have opened a window on the deconfinement regime. All these experiments leave legacies of quality, precision, and unsolved mysteries for quarkonium physics, and therefore beg for continuing investigations. The plethora of newly-found quarkonium-like states unleashed a flood of theoretical investigations into new forms of matter such as quark-gluon hybrids, mesonic molecules, and tetraquarks. Measurements of the spectroscopy, decays, production, and in-medium behavior of c\bar{c}, b\bar{b}, and b\bar{c} bound states have been shown to validate some theoretical approaches to QCD and highlight lack of quantitative success for others. The intriguing details of quarkonium suppression in heavy-ion collisions that have emerged from RHIC have elevated the importance of separating hot- and cold-nuclear-matter effects in quark-gluon plasma studies. This review systematically addresses all these matters and concludes by prioritizing directions for ongoing and future efforts.Comment: 182 pages, 112 figures. Editors: N. Brambilla, S. Eidelman, B. K. Heltsley, R. Vogt. Section Coordinators: G. T. Bodwin, E. Eichten, A. D. Frawley, A. B. Meyer, R. E. Mitchell, V. Papadimitriou, P. Petreczky, A. A. Petrov, P. Robbe, A. Vair

Formation of calcite by chemolithoautotrophic bacteria – a new hypothesis, based on microcrystalline cave pisoids

A new mechanism, stimulating the precipitation of calcite, is postulated. The supersaturation with respect to carbonate minerals is changed, as a result of CO2consumption by chemolithoautotrophic, hydrogen-oxidizing bacteria. This mechanism controls the growth of atypical, microcrystalline cave pisoids in Perlová Cave, in Slovakia. The pisoids grow under calm conditions in rimstone pools, where they are bathed continuously in stagnant water. The water is supersaturated, with respect to calcite and aragonite. The bacteria inhabit the outer parts of the pisoids, covered by biofilms. The biofilm influences the supply of the Ca2+ ion, slows down the precipitation rate, and favors calcite precipitation over that of aragonite. The calcite initially precipitates as bacterial replicas, which further act as seeds for the growing calcite crystals. This process leads to the obliteration of the primary, bacterial fabrics. Since hydrogen-oxidizing bacteria occur in a wide spectrum of natural habitats, the mechanism of calcification, postulated above, also may operate in other environments