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

Signal Propagation in Collisional Plasma with Negative Ions

The transport of charged species in collisional currentless plasmas is traditionally thought of as a diffusion-like process. In this paper, it is demonstrated that, in contrast to two-component plasma, containing electrons and positive ions, the transport of additional ions in multi-species plasmas is not governed by diffusion, rather described by nonlinear convection. As a particular example, plasmas with the presence of negative ions have been studied. The velocity of a small perturbation of negative ions was found analytically and validated by numerical simulation. As a result of nonlinear convection, initially smooth ion density profiles break and form strongly inhomogeneous shock-like fronts. These fronts are different from collisionless shocks and shocks in fully ionized plasma. The structure of the fronts has been found analytically and numerically

Assessing hyperthermia-induced vasodilation in human skin in vivo using optoacoustic mesoscopy.

The aim of this study was to explore the unique imaging abilities of optoacoustic mesoscopy to visualize skin structures and microvasculature with the view of establishing a robust approach for monitoring heat-induced hyperemia in human skin in vivo. Using raster-scan optoacoustic mesoscopy (RSOM), we investigated whether optoacoustic (photoacoustic) mesoscopy can identify changes in skin response to local heating at microvasculature resolution in a cross-sectional fashion through skin in the human forearm. We visualized the heat-induced hyperemia for the first time with single-vessel resolution throughout the whole skin depth. We quantified changes in total blood volume in the skin and their correlation with local heating. In response to local heating, total blood volume increased 1.83- and 1.76-fold, respectively, in the volar and dorsal aspects of forearm skin. We demonstrate RSOM imaging of the dilation of individual vessels in the skin microvasculature, consistent with hyperemic response to heating at the skin surface. Our results demonstrate great potential of RSOM for elucidating the morphology, functional state and reactivity of dermal microvasculature, with implications for diagnostics and disease monitoring. Image: Cross-sectional view of skin microvasculature dilated in response to hyperthermia

Fast modelling of low pressure radio-frequency collisional capacitively coupled discharge and investigation of the formation of non-Maxwellian electron distribution function

The principles of fast-modelling (FM) of low-pressure radio-frequency capacitively coupled discharge are presented. They are based on averaging over fast electron and ion motions and on eliminating a small spatial scale, the Debye radius. As a result, the solution of self-consistent system of electron kinetic equation, the Poisson, and ion continuity equations takes approximately 10 min on 486 PC. The calculation of discharge parameters has been performed for a wide range of current and pressure. The comparison with full-scale Monte-Carlo calculations and experimental data has been performed. The performed comparisons demonstrate that developed method of the fast-modeling has a good accuracy for calculating the global parameters such as central plasma density, applied voltage, sheath thickness, ionization rate, etc., and the profiles of plasma density and the electric fields. The accuracy of the electron distribution function (EDF) calculation is high when EDF form is not enriched by slow electrons, and seems satisfactory in the case of a strongly peaked EDF. The results are in qualitatively good agreement with the experiment. The quantitative agreement is mainly within a factor of two. This discrepancy can be attributed to the fact that the EDF form is very sensitive to the details of plasma description, e.g. small variation of cross-sections results in considerable changes in the EDF. The mechanism of non-Maxwellian EDF formation due to non-localicty effects has been analyzed. The evolution of the low pressure radio-frequency collisional capacitively coupled discharge with current and pressure variation has been investigated. (orig.)Available from TIB Hannover: RO 9159(54) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman