Measurement of the pseudoscalar mixing angle and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"><mml:msup><mml:mi>η</mml:mi><mml:mo>′</mml:mo></mml:msup></mml:math> gluonium content with the KLOE detector

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 hc(1P ), χc2(2P ), B + c , and η b (1S). In addition, the unexpected and still-fascinating X(3872) has been joined by * Editors † Section coordinators ‡ Corresponding author: bkh2@cornell.edu more than a dozen other charmonium-and bottomonium-like "XY Z" 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 cc, bb, and bc 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 industrialstrength 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 hotand 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.

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“…(113). The measured value [470] from charmonium is consistent with that obtained from other sources [479][480][481].…”

Section: Nonobservation Of ψ(2s) υ(1s) → γηsupporting

confidence: 86%

Heavy quarkonium: progress, puzzles, and opportunities

Brambilla¹,

Eidelman²,

Heltsley³

et al. 2011

Advances in the Physics of Particles and Nuclei

103

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“…The mixtures among the η q , η s and a possible glueball [85][86][87][88] will be neglected in this work. For the decay constant and the mixing angle φ, we have the forms as [89,90],…”

Section: Frameworkmentioning

confidence: 99%

Quasi-two-body decays B(s)→Pρ→Pππ in the perturbative QCD approach

Xiao

et al. 2017

Phys. Rev. D

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In this work, we calculate the CP -averaged branching ratios and the direct CP -violating asymmetries of the quasi-two-body decays B (s) → P (ρ →)ππ by employing the perturbative QCD (PQCD) approach (here P stands for a light pseudoscalar meson π, K, η or η ′ ). The vector current timelike form factor Fπ, which contains the final-state interactions between the pion pair in the resonant region associated with the P -wave states ρ(770) along with the two-pion distribution amplitudes, is employed to describe the interactions between the ρ and the pion pair under the hypothesis of the conserved vector current. We found that (a) the PQCD predictions for the branching ratios and the direct CP -violating asymmetries for most considered B (s) → P (ρ →)ππ decays agree with currently available data within errors, (b) for B(B → π 0 ρ 0 → π 0 (π + π − ), the PQCD prediction is much smaller than the measured one, and (c) for the B + → π + (ρ 0 →)π + π − decay mode, there is a negative CP asymmetry (−27.5 +3.0 −3.7 )%, which agrees with other theoretical predictions but is different in sign from those reported by BABAR and LHCb Collaborations.

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“…Recently, the KLOE Collaboration [45] extracted the pseudoscalar mixing angle φ in the QF basis by measuring the ratio BR(φ → η ′ γ)/BR(φ → ηγ). The measured values are φ = (39.7 ± 0.7)…”

Section: Form Factors For the Rare B S → P Decays In Our Lfqmmentioning

confidence: 99%