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(c)(1P), chi(c2)(2P), B-c(+), and eta(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 (c) over bar, b (b) over bar, and b (c) over bar 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.

/pdf/heavy-quarkonium-progress-puzzles-and-opportunities-2tru0l8jyp.pdf

Heavy quarkonium: progress, puzzles, and opportunities

This work is on the Physics of the B Factories. Part A of this book contains a brief description of the SLAC and KEK B Factories as well as their detectors, BaBar and Belle, and data taking related issues. Part B discusses tools and methods used by the experiments in order to obtain results. The results themselves can be found in Part C.

The Physics of the B Factories

The extremely precise extraction of the proton radius obtained by Pohl et al. from the measured energy difference between the 2P and 2S states of muonic hydrogen disagrees significantly with that extracted from electronic hydrogen or elastic electron–proton scattering. This discrepancy is the proton radius puzzle. In this review, we explain the origins of the puzzle and the reasons for believing it to be very significant. We identify various possible solutions of the puzzle and discuss future research needed to resolve the puzzle.

https://www.annualreviews.org/doi/pdf/10.1146/annurev-nucl-102212-170627

Muonic Hydrogen and the Proton Radius Puzzle

This review describes the history of the discovery of the violation of the spatial parity P, the charge conjugation parity C, and the combined parity CP. The hypothesis of the existence of mirror particles was intended by its authors to restore the symmetry between left and right. The review presents the emergence and evolution of the concepts of 'mirror particles' and 'mirror matter' and can serve as a concise travel guide to 'mirror land.' An important part of the review is the list of about 200 references with their titles.

http://iopscience.iop.org/article/10.1070/PU2007v050n04ABEH006227/pdf

Mirror particles and mirror matter: 50 years of speculation and searching

We present a scenario in which a remarkably simple relation linking dark matter properties and neutrino masses naturally emerges. This framework points towards a low energy theory where the neutrino mass originates from the existence of a light scalar dark matter particle in the keV-MeV mass range. We discuss different ways to constrain and test this scenario by means of astrophysical and cosmological observations as well as laboratory experiments. Finally, we point out that one interesting aspect is that the implied mass range is compatible with the one required for the explanation of the mysterious emission of 511 keV photons from the center of our galaxy in terms of dark matter annihilation into ${e}^{+}{e}^{\ensuremath{-}}$ pairs.

Is it possible to explain neutrino masses with scalar dark matter

The decay psi(2S)-->(KSKL0)-K-0 is observed using psi(2S) data collected with the Beijing Spectrometer at the Beijing Electron-Positron Collider; the branching fraction is determined to be B(psi(2S)-->(KSKL0)-K-0)=(5.24+/-0.47+/-0.48)x10(-5). Compared with J/psi-->(KSKL0)-K-0, the psi(2S) branching fraction is enhanced relative to the prediction of the perturbative QCD "12%" rule. The result, together with the branching fractions of psi(2S) decays to other pseudoscalar meson pairs (pi(+)pi(-) and K+K-), is used to investigate the relative phase between the three-gluon and the one-photon annihilation amplitudes of psi(2S) decays.

Observation of the decay psi(2S)-->K0SK0L.

Using a data sample of 58x10(6) J/psi decays collected with the Beijing Spectrometer II detector at the Beijing Electron Positron Collider, searches for invisible decays of eta and eta(') in J/psi to phi eta and phi eta(') are performed. The phi signals, which are reconstructed in K+K- final states, are used to tag the eta and eta(') decays. No signals are found for the invisible decays of either eta or eta('), and upper limits at the 90% confidence level are determined to be 1.65x10(-3) for the ratio B(eta'-> invisible/B(eta ->gamma gamma) and 6.69x10(-2) for B(eta(')-> invisible)/B(eta(')->gamma gamma). These are the first searches for eta and eta(') decays into invisible final states.

Search for invisible decays of eta and eta' in J/psi --> phi eta and phi eta'.

An enhancement near the m(p)+M-Lambda mass threshold is observed in the combined p(U) over bar and (p) over bar Lambda invariant-mass spectrum from J/psi-->pK(-)(U) over bar +c.c. decays. It can be fit with an S-wave Breit-Wigner resonance with a mass m=2075+/-12(stat)+/-5(syst) MeV and a width of Gamma=90+/-35(stat)+/-9(syst) MeV; it can also be fit with a P-wave Breit-Wigner resonance. Evidence for a similar enhancement is also observed in psi'-->pK(-)(U) over bar +c.c. decays. The analysis is based on samples of 5.8x10(7)J/psi and 1.4x10(7)psi' decays accumulated in the BES II detector at the Beijing Electron-Positron Collider.

Observation of a threshold enhancement in the plambda invariant-mass spectrum.

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Bes Callaboration

Author Tools

Chat about Author

Papers

Observation of the decay psi(2S)-->K0SK0L.

Search for invisible decays of eta and eta' in J/psi --> phi eta and phi eta'.

Observation of a threshold enhancement in the plambda invariant-mass spectrum.