Heavy quarkonium : progress, puzzles, and opportunities.

Journal Article · Sat Jan 01 04:00:00 EST 2011 · European Physical Journal. C, Particles and Fields

DOI:https://doi.org/10.1140/epjc/s10052-010-1534-9· OSTI ID:1006258

Brambilla, N; Eidelman, S; Heltsley, B K; Vogt, R; Bodwin, G T; LLNL,

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 at BESIII, the LHC, RHIC, FAIR, the Super Flavor and/or Tau-Charm factories, JLab, the ILC, and beyond. The list of newly found conventional states expanded to include h{sub c}(1P), {chi}{sub c2} (2P), B{sub c}{sup +}, and {eta}{sub b} (1S). In addition, the unexpected and still-fascinating X(3872) has been joined by more than a dozen other charmonium- and bottomonium-like 'XYZ' states that appear to lie outside the quark model. Many of these still need experimental confirmation. The plethora of new 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. Lattice QCD has grown from a tool with computational possibilities to an industrial-strength effort now dependent more on insight and innovation than pure computational power. New effective field theories for the description of quarkonium in different regimes have been developed and brought to a high degree of sophistication, thus enabling precise and solid theoretical predictions. Many expected decays and transitions have either been measured with precision or for the first time, but the confusing patterns of decays, both above and below open-flavor thresholds, endure and have deepened. 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.

• Research Organization: Argonne National Laboratory (ANL)
• Sponsoring Organization: SC; European Union Marie Curie Research Network; German Research Foundation; ational Natural Science of Foundation of China
• DOE Contract Number: AC02-06CH11357
• OSTI ID: 1006258
• Report Number(s): ANL-HEP-PR-10-44
• Journal Information: European Physical Journal. C, Particles and Fields, Journal Name: European Physical Journal. C, Particles and Fields Journal Issue: 2 ; 2011 Vol. 71; ISSN 1434-6044
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

43 PARTICLE ACCELERATORS
ACCURACY
BOUND STATE
CERN
CHARMONIUM
EXPLOSIONS
FERMILAB TEVATRON
FIELD THEORIES
PHYSICS
POLARIZATION
PRODUCTION
QUANTUM CHROMODYNAMICS
QUARK MATTER
QUARK MODEL
QUARKONIUM
RECOMMENDATIONS
SPECTROSCOPY