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This is a contribution to the review "50 Years of Quantum Chromdynamics" edited by F. Gross and E. Klempt [arXiv:2212.11107], to be published in EPJC. The contribution reviews the properties of baryons with one heavy flavor: the lifetimes of ground states and the spectrum of excited states. The importance of symmetries to understand the excitation spectrum is underlined. An overview of searches for pentaquarks is given., 10 pages, 8 tables, 7 figures

This is a contribution to the review "50 Years of Quantum Chromdynamics" edited by F. Gross and E. Klempt [arXiv:2212.11107], to be published in EPJC. The contribution reviews the new baryon resonances derived from photoproduction experiments. Implications of the new results for the interpretation of baryons are discussed., 11 pages, 7 figures, 2 tables

The Review summarizes much of particle physics and cosmology. Using data from previous editions, plus 2,143 new measurements from 709 papers, we list, evaluate, and average measured properties of gauge bosons and the recently discovered Higgs boson, leptons, quarks, mesons, and baryons. We summarize searches for hypothetical particles such as supersymmetric particles, heavy bosons, axions, dark photons, etc. Particle properties and search limits are listed in Summary Tables. We give numerous tables, figures, formulae, and reviews of topics such as Higgs Boson Physics, Supersymmetry, Grand Unified Theories, Neutrino Mixing, Dark Energy, Dark Matter, Cosmology, Particle Detectors, Colliders, Probability and Statistics. Among the 120 reviews are many that are new or heavily revised, including a new review on Machine Learning, and one on Spectroscopy of Light Meson Resonances., The Review is divided into two volumes. Volume 1 includes the Summary Tables and 97 review articles. Volume 2 consists of the Particle Listings and contains also 23 reviews that address specific aspects of the data presented in the Listings., The complete Review (both volumes) is published online on the website of the Particle Data Group (pdg.lbl.gov) and in a journal. Volume 1 is available in print as the PDG Book. A Particle Physics Booklet with the Summary Tables and essential tables, figures, and equations from selected review articles is available in print, as a web version optimized for use on phones, and as an Android app., Progress of Theoretical and Experimental Physics, 2022 (8), ISSN:2050-3911

The scalar glueball is observed in a coupled-channel analysis of the $S$-wave amplitude from BESIII data on radiative $J/ψ$ decays and further data. Ten scalar isoscalar resonances were required to fit the data. Five of them were interpreted as mainly-singlet, five as mainly-octet resonances in SU(3). The yield of resonances showed a striking peak with properties expected from a scalar glueball. The $D$ wave amplitude in the BESIII data on radiative $J/ψ$ decays reveales a high-mass structure which can be described by a single Breit-Wigner or by the sum of three $ϕϕ$ resonances interpreted as tensor glueballs a long time ago. The structure - and further tensor resonances observed in radiative $J/ψ$ decays - are tentatively interpreted as tensor glueball. In $J/ψ$ decays into $γπ^0π^0η'$ several resonances are reported. The possibility is discussed that the pseudoscalar glueball might be hidden in these data., Contribution to XVth Quark confinement and the Hadron spectrum conference, August 1st - 6th, 2022, University of Stavanger, Norway

This is a contribution to the review "50 Years of Quantum Chromdynamics" edited by F. Gross and E. Klempt [arXiv:2212.11107], to be published in EPJC. The contribution remembers the early searches and explains how to find a glueball, based on its properties. The results of a coupled-channel analysis are presented that provides evidence for the scalar glueball and first hints for the tensor glueball. Data on radiative decays of $\psi(2S)$ and $\Upsilon(1S)$ show scalar intensity that is likely due to glueball production., Comment: 9 pages, 12 figures

A coupled-channel analysis of BESIII data on radiative $J/��$ decays into $����$, $K\bar K$, $����$ and $����$ has been performed. The partial-wave amplitude is constrained by a large number of further data. The analysis finds ten isoscalar scalar mesons. Their masses, widths and decay modes are determined. The scalar mesons are interpreted as mainly SU(3)-singlet and mainly octet states. Octet isoscalar scalar states are observed with significant yields only in the 1500-2100\,MeV mass region. Singlet scalar mesons are produced over a wide mass range but their yield peaks in the same mass region. The peak is interpreted as scalar glueball. Its mass and width are determined to $M=1865$\er25$^{+10}_{-30}$ {\rm MeV} and $��= 370$\er$50^{+30}_{-20}$ {\rm MeV}, its yield in radiative $J/��$ decays to ($5.8\pm 1.0)\,10^{-3}$., 11 pages, 4 figures

We highlight topical issues in hyperon spectroscopy that will be accessible when a secondary beam of neutral kaons is created in Hall D at Jefferson Lab as proposed to the JLab Program Advisory Committee. The new beam will have a flux of $10^4$ $K_L$/s. The reaction products will be analyzed in the GlueX experimental setup. We point out which physical questions need to be answered and suggest a number of novel experiments. In particular we suggest to measure the presently disputed SU(3) structure of the $\Lambda(1405)$, to search for Pentaquarks mit exotic quantum numbers and to search for baryons belonging to the SU(6) 20-plet representation., Comment: 10 pages, 6 figures

A coupled-channel analysis has been performed to identify the spectrum of scalar mesons. The data include BESIII data on radiative $J/\psi$ decays into $\pi^0\pi^0$,$K_SK_S$, $\eta\eta$, and $\omega\phi$, 15 Dalitz plots from $\bar pN$ annihilation at rest at LEAR, the CERN-Munich multipoles for $\pi\pi$ elastic scattering, the $S$-wave from BNL data on $\pi\pi$ scattering into $K_SK_S$, from GAMS data on $\pi\pi\to \pi^0\pi^0, \eta\eta$, and $\eta\eta'$, and NA48/2 data on low-mass $\pi\pi$ interactions from $K^\pm\to\pi\pi e^\pm\nu$ decays. The analysis reveals the existence of ten scalar isoscalar resonances. The resonances can be grouped into two classes: resonances with a large SU(3) singlet component and those with a large octet component. The production of isoscalar resonances with a large octet component should be suppressed in radiative $J/\psi$ decays. However, in a limited mass range centered at 1900\,MeV, these mesons are produced abundantly. Mainly-singlet scalar resonances are produced over the full mass range but with larger intensity at 1900\,MeV. The total scalar isoscalar yield in radiative decays into scalar mesons shows a clear peak which is interpreted as the scalar glueball of lowest mass., Comment: Contribution to Quark Confinement and the Hadron Spectrum 2021. 6 pages, 5 figures, 2 tables

The evidence for the existence of mesons with exotic quantum numbers and of hybrid candidates with non-exotic quantum numbers is critically reviewed, including candidates with hidden charm. Aims and methods of future searches for hybrid mesons are briefly discussed., Pleanry talk at Hadron07, Frascati, Italy, October 8-12, 2007

The spectroscopy of light and heavy mesons is reviewed with emphasis on glueballs, hybrids, and tetraquarks., 266 pages, 117 figures, 39 tables. to be published in Physics Reports

Hadron spectroscopy has received revitalised interest due to the discovery of states with unexpected properties. Discussed are the recent findings at BABAR, CLEO, BELLE and BES. A detailed report is given on the many experiments reporting evidence (or counter--evidence) for the $\Theta^+(1540)$ and other pentaquarks. In conventional meson and in baryon spectroscopy, evidence is emerging that one--gluon--exchange does not provide the appropiate means to understand low--energy QCD; instanton--induced interactions yield much more insight. In particular the rich spectrum of baryon resonances is very well suited to test dynamical quark models using constituent quarks, a confinement potential plus some residual interactions. A still controversial issue is the question if glueballs and hybrids exist. There is the possibility that two $q\bar q$ scalar states and a glueball form three observed resonances by mixing. However, there is also rather conclusive evidence against this interpretation. Mesons with exotic quantum numbers have been reported but there is no reason why they should be hybrids: a four--quark interpretation is enforced for the $\pi_1(1400)$ and not ruled out in the other cases., Comment: 139 pages, 91 figures, lectures at 18th Annual Hampton University Graduate Studies, Jefferson Lab, Newport News, Virginia, June 2-20, 2003

The Particle Data Group decided to split the $��(1440)$ into two states, called $��_L$ and $��_H$. The $��(1295)$ and the $��_H$ are supposed to be the radial excitations of the $��$ and $��'$, respectively. The $��_L$ state cannot be accomodated in a quark model; it cannot be a $q\bar q$ state, however, it might be a glueball. In this contribution it is shown that that the $��(1295)$ does not have the properties which must be expected for a radially excited state. The splitting of the $��(1440)$ is traced to a node in the wave function of a radial excitation. Hence the two peaks, $��_L$ and $��_H$, originate from one resonance which is interpreted here as first radial excitation of the $��$., 8 pages, 3 figures, contribution to ICHEP04, Beijing, 2004

We analyze the current status of three P-wave baryon states $N(1710){1/ 2}^+$, $N(1900){3/2}^+$, and $\Delta(1600){3/2}^+$ as given in the Review of Particles Physics (RPP). Since the evidence for a particle's existence is linked to its RPP "star" rating, we discuss its subjective present definition. We also present the accumulating evidence supporting these states and give our new "star" rating recommendations., Comment: 6 pages, 2 figures

This paper presents a comprehensive review of both the theory and experimental successes of Quantum Chromodynamics, starting with its emergence as a well defined theory in 1972-73 and following developments and results up to the present day. Topics include a review of the earliest theoretical and experimental foundations; the fundamental constants of QCD; an introductory discussion of lattice QCD, the only known method for obtaining exact predictions from QCD; methods for approximating QCD, with special focus on effective field theories; QCD under extreme conditions; measurements and predictions of meson and baryon states; a special discussion of the structure of the nucleon; techniques for study of QCD at high energy, including treatment of jets and showers; measurements at colliders; weak decays and quark mixing; and a section on the future, which discusses new experimental facilities or upgrades currently funded. The paper is intended to provide a broad background for Ph.D. students and postdocs starting their career. Some contributions include personal accounts of how the ideas or experiments were developed., Comment: Invited volume for the EJPC; 567 pages if text/figures and 4783 references occupying about 160 additional pages. arXiv abstract abridged, for the complete abstract please see the full text

Das Ende der 90er Jahre neu entstandene Crystal Barrel-Experiment am Bonner Elektronenbeschleuniger ELSA, kurz CB-ELSA-Experiment, dient hauptsächlich dem Studium der Photoproduktion am Proton bei Strahlimpulsen zwischen 0.8 GeV/c und 3.2 GeV/c. Ziel dieses Experimentes ist es, neue Erkenntnisse über das Spektrum der leichten Baryonen zu gewinnen und auch einige wichtige Beiträge für ein besseres Verständnis des Spektrums der leichten Mesonen zu liefern. Die Besonderheit dieses Experimentes liegt in der Topologie der Detektoren. Das Herzstück bildet hierbei das Crystal Barrel-Kalorimeter, das unter Zuhilfenahme weiterer Detektoren die vollständige Erfassung von Ereignissen mit neutralen Mesonen über einen Raumwinkel von nahezu 4[pi] erlaubt. Die vorliegende Arbeit befasst sich zum einen mit dem Aufbau des Flüssig-Wasserstoff-Targets, für dessen Anpassung an die hohen Ansprüche des Experimentes eine umfangreiche Entwicklungsarbeit erforderlich war. Zum anderen bildet den Hauptteil der Arbeit die Untersuchung der photoinduzierten Reaktionen [gamma]proton nach proton[pi]0[pi]0 und [gamma]proton nach proton[pi]0[eta] bei einem Strahlimpuls unpolarisierter Elektronen von 2.6 GeV/c. Beim Studium dieser Reaktionen zeigen sich Hinweise auf missing resonances, die sequentiell über verschiedene Baryonenresonanzen zerfallen. Darüber hinaus gibt es deutliche Evidenzen für die f0(980)- und a0(980)-Photoproduktion, deren weitergehende Untersuchungen wichtige Beiträge zur Klärung des bis heute noch nicht verstandenen skalaren Mesonennonetts liefern könnten.