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1. 50 Years of quantum chromodynamics

Author: Franz Gross, Eberhard Klempt, Stanley J. Brodsky, Andrzej J. Buras, Volker D. Burkert, Gudrun Heinrich, Karl Jakobs, Curtis A. Meyer, Kostas Orginos, Michael Strickland, Johanna Stachel, Giulia Zanderighi, Nora Brambilla, Peter Braun-Munzinger, Daniel Britzger, Simon Capstick, Tom Cohen, Volker Crede, Martha Constantinou, Christine Davies, Luigi Del Debbio, Achim Denig, Carleton DeTar, Alexandre Deur, Yuri Dokshitzer, Hans Günter Dosch, Jozef Dudek, Monica Dunford, Evgeny Epelbaum, Miguel A. Escobedo, Harald Fritzsch, Kenji Fukushima, Paolo Gambino, Dag Gillberg, Steven Gottlieb, Per Grafstrom, Massimiliano Grazzini, Boris Grube, Alexey Guskov, Toru Iijima, Xiangdong Ji, Frithjof Karsch, Stefan Kluth, John B. Kogut, Frank Krauss, Shunzo Kumano, Derek Leinweber, Heinrich Leutwyler, Hai-Bo Li, Yang Li, Bogdan Malaescu, Chiara Mariotti, Pieter Maris, Simone Marzani, Wally Melnitchouk, Johan Messchendorp, Harvey Meyer, Ryan Edward Mitchell, Chandan Mondal, Frank Nerling, Sebastian Neubert, Marco Pappagallo, Saori Pastore, José R. Peláez, Andrew Puckett, Jianwei Qiu, Klaus Rabbertz, Alberto Ramos, Patrizia Rossi, Anar Rustamov, Andreas Schäfer, Stefan Scherer, Matthias Schindler, Steven Schramm, Mikhail Shifman, Edward Shuryak, Torbjörn Sjöstrand, George Sterman, Iain W. Stewart, Joachim Stroth, Eric Swanson, Guy F. de Téramond, Ulrike Thoma, Antonio Vairo, Danny van Dyk, James Vary, Javier Virto, Marcel Vos, Christian Weiss, Markus Wobisch, Sau Lan Wu, Christopher Young, Feng Yuan, Xingbo Zhao, and Xiaorong Zhou
Subjects: Astrophysics, QB460-466, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract: Abstract Quantum Chromodynamics, the theory of quarks and gluons, whose interactions can be described by a local SU(3) gauge symmetry with charges called “color quantum numbers”, is reviewed; the goal of this review is to provide advanced Ph.D. students a comprehensive handbook, helpful for their research. When QCD was “discovered” 50 years ago, the idea that quarks could exist, but not be observed, left most physicists unconvinced. Then, with the discovery of charmonium in 1974 and the explanation of its excited states using the Cornell potential, consisting of the sum of a Coulomb-like attraction and a long range linear confining potential, the theory was suddenly widely accepted. This paradigm shift is now referred to as the November revolution. It had been anticipated by the observation of scaling in deep inelastic scattering, and was followed by the discovery of gluons in three-jet events. The parameters of QCD include the running coupling constant, $$\alpha _s(Q^2)$$ α s ( Q 2 ) , that varies with the energy scale $$Q^2$$ Q 2 characterising the interaction, and six quark masses. QCD cannot be solved analytically, at least not yet, and the large value of $$\alpha _s$$ α s at low momentum transfers limits perturbative calculations to the high-energy region where $$Q^2\gg \varLambda _{{\textrm{QCD}}} ^2\simeq $$ Q 2 ≫ Λ QCD 2 ≃ (250 MeV) $$^2$$ 2 . Lattice QCD (LQCD), numerical calculations on a discretized space-time lattice, is discussed in detail, the dynamics of the QCD vacuum is visualized, and the expected spectra of mesons and baryons are displayed. Progress in lattice calculations of the structure of nucleons and of quantities related to the phase diagram of dense and hot (or cold) hadronic matter are reviewed. Methods and examples of how to calculate hadronic corrections to weak matrix elements on a lattice are outlined. The wide variety of analytical approximations currently in use, and the accuracy of these approximations, are reviewed. These methods range from the Bethe–Salpeter, Dyson–Schwinger coupled relativistic equations, which are formulated in both Minkowski or Euclidean spaces, to expansions of multi-quark states in a set of basis functions using light-front coordinates, to the AdS/QCD method that imbeds 4-dimensional QCD in a 5-dimensional deSitter space, allowing confinement and spontaneous chiral symmetry breaking to be described in a novel way. Models that assume the number of colors is very large, i.e. make use of the large $$N_c$$ N c -limit, give unique insights. Many other techniques that are tailored to specific problems, such as perturbative expansions for high energy scattering or approximate calculations using the operator product expansion are discussed. The very powerful effective field theory techniques that are successful for low energy nuclear systems (chiral effective theory), or for non-relativistic systems involving heavy quarks, or the treatment of gluon exchanges between energetic, collinear partons encountered in jets, are discussed. The spectroscopy of mesons and baryons has played an important historical role in the development of QCD. The famous X,Y,Z states – and the discovery of pentaquarks – have revolutionized hadron spectroscopy; their status and interpretation are reviewed as well as recent progress in the identification of glueballs and hybrids in light-meson spectroscopy. These exotic states add to the spectrum of expected $$q{{\bar{q}}}$$ q q ¯ mesons and qqq baryons. The progress in understanding excitations of light and heavy baryons is discussed. The nucleon as the lightest baryon is discussed extensively, its form factors, its partonic structure and the status of the attempt to determine a three-dimensional picture of the parton distribution. An experimental program to study the phase diagram of QCD at high temperature and density started with fixed target experiments in various laboratories in the second half of the 1980s, and then, in this century, with colliders. QCD thermodynamics at high temperature became accessible to LQCD, and numerical results on chiral and deconfinement transitions and properties of the deconfined and chirally restored form of strongly interacting matter, called the Quark–Gluon Plasma (QGP), have become very precise by now. These results can now be confronted with experimental data that are sensitive to the nature of the phase transition. There is clear evidence that the QGP phase is created. This phase of QCD matter can already be characterized by some properties that indicate, within a temperature range of a few times the pseudocritical temperature, the medium behaves like a near ideal liquid. Experimental observables are presented that demonstrate deconfinement. High and ultrahigh density QCD matter at moderate and low temperatures shows interesting features and new phases that are of astrophysical relevance. They are reviewed here and some of the astrophysical implications are discussed. Perturbative QCD and methods to describe the different aspects of scattering processes are discussed. The primary parton–parton scattering in a collision is calculated in perturbative QCD with increasing complexity. The radiation of soft gluons can spoil the perturbative convergence, this can be cured by resummation techniques, which are also described here. Realistic descriptions of QCD scattering events need to model the cascade of quark and gluon splittings until hadron formation sets in, which is done by parton showers. The full event simulation can be performed with Monte Carlo event generators, which simulate the full chain from the hard interaction to the hadronic final states, including the modelling of non-perturbative components. The contribution of the LEP experiments (and of earlier collider experiments) to the study of jets is reviewed. Correlations between jets and the shape of jets had allowed the collaborations to determine the “color factors” – invariants of the SU(3) color group governing the strength of quark–gluon and gluon–gluon interactions. The calculated jet production rates (using perturbative QCD) are shown to agree precisely with data, for jet energies spanning more than five orders of magnitude. The production of jets recoiling against a vector boson, $$W^\pm $$ W ± or Z, is shown to be well understood. The discovery of the Higgs boson was certainly an important milestone in the development of high-energy physics. The couplings of the Higgs boson to massive vector bosons and fermions that have been measured so far support its interpretation as mass-generating boson as predicted by the Standard Model. The study of the Higgs boson recoiling against hadronic jets (without or with heavy flavors) or against vector bosons is also highlighted. Apart from the description of hard interactions taking place at high energies, the understanding of “soft QCD” is also very important. In this respect, Pomeron – and Odderon – exchange, soft and hard diffraction are discussed. Weak decays of quarks and leptons, the quark mixing matrix and the anomalous magnetic moment of the muon are processes which are governed by weak interactions. However, corrections by strong interactions are important, and these are reviewed. As the measured values are incompatible with (most of) the predictions, the question arises: are these discrepancies first hints for New Physics beyond the Standard Model? This volume concludes with a description of future facilities or important upgrades of existing facilities which improve their luminosity by orders of magnitude. The best is yet to come!
Published: 2023
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2. Scalar mesons and the fragmented glueball

Author: Eberhard Klempt
Subjects: Physics, QC1-999
Abstract: The center-of-gravity rule is tested for heavy and light-quark mesons. In the heavy-meson sector, the rule is excellently satisfied. In the light-quark sector, the rule suggests that the a0(980) could be the spin-partner of a2(1320), a1(1260), and b1(1235); f0(500) the spin-partner of f2(1270), f1(1285), and h1(1170); and f0(980) the spin-partner of f2′(1525), f1(1420), and h1(1415). From the decay and the production of light scalar mesons we find a consistent mixing angle θs=(14±4)∘. We conclude that f0(980) is likely “octet-like” in SU(3) with a slightly larger ss¯ content and f0(500) is SU(3) “singlet-like” with a larger nn¯ component. The a0(1450), K0⁎(1430), f0(1500) and f0(1370) are suggested as nonet of radial excitations. The scalar glueball is discussed as part of the wave function of scalar isoscalar mesons and not as additional “intruder”. It seems not to cause supernumerosity.
Published: 2021
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3. The scalar and tensor glueball in production and decay

Author: Eberhard Klempt
Subjects: Physics, QC1-999
Abstract: Evidence for the scalar and the tensor glueball is reported. The evidence stems from an analysis of BESIII data on radiative $J/\psi$ data into $\pi^0\pi^0$, $K_SK_S$, $\eta\eta$, and $\phi\omega$ [1]. The coupled-channel analysis is contrained by a large number of further data. The scalar intensity is described by ten scalar isoscalar mesons, covering the range from $f_0(500)$ to $f_0(2330)$. Five resonances are interpreted as mainly-singlet states in SU(3), five as mainly-octet states. The mainly-singlet resonances are produced over the full mass range, the production of octet states is limited to the 1500 to 2100 MeV mass range and shows a large peak. The peak is interpreted as scalar glueball. Its mass, width and yield are determined to $\rm M_{glueball}=(1865\pm 25)$ MeV, $\Gamma_{\rm glueball} =\rm (370\pm 50^{+30}_{-20}) MeV$, $\rm Y_{J/\psi\to \gamma G_0}=(5.8\pm1.0)\cdot 10^{-3}$. The study of the decays of the scalar mesons identifies significant glueball fractions [2]. The tensor wave shows the $f_2(1270)$ and $f_2'(1525)$ and a small enhancement at $M=2210\pm40$ MeV, $\Gamma=\rm (355^{+60}_{-30}) MeV$ [3]. An interpretation of these data is suggested.
Published: 2022
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4. Glueballs in Radiative $J/\psi$ Decays

Author: Eberhard Klempt
Subjects: High Energy Physics - Phenomenology
Abstract: The scalar glueball is observed in a coupled-channel analysis of the $S$-wave amplitude from BESIII data on radiative $J/\psi$ 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 $J/\psi$ decays reveales a high-mass structure which can be described by a single Breit-Wigner or by the sum of three $\phi\phi$ resonances interpreted as tensor glueballs a long time ago. The structure - and further tensor resonances observed in radiative $J/\psi$ decays - are tentatively interpreted as tensor glueball. In $J/\psi$ decays into $\gamma\pi^0\pi^0\eta'$ several resonances are reported. The possibility is discussed that the pseudoscalar glueball might be hidden in these data., Comment: Contribution to XVth Quark confinement and the Hadron spectrum conference, August 1st - 6th, 2022, University of Stavanger, Norway
Published: 2022

5. Proton-η′ interactions at threshold

Author: Michael Dugger, Barry Ritchie, A. V. Sarantsev, A. V. Anisovich, Volker D. Burkert, U. Thoma, V. A. Nikonov, and Eberhard Klempt
Subjects: Physics, Nuclear and High Energy Physics, Range (particle radiation), Meson, Proton, 010308 nuclear & particles physics, media_common.quotation_subject, Partial wave analysis, Nuclear Theory, Scattering length, 01 natural sciences, Asymmetry, Resonance (particle physics), lcsh:QC1-999, Scattering amplitude, 0103 physical sciences, Atomic physics, Nuclear Experiment, 010306 general physics, lcsh:Physics, media_common
Abstract: Recent data on photoproduction of η′ mesons off protons have been included in the data base for the Bonn–Gatchina partial wave analysis. The real and imaginary parts of the S-wave η′p→η′p scattering amplitude in the threshold region were fit to yield the η′p scattering length and the interaction range. This new analysis found |aη′p|=(0.403±0.015±0.060) fm and a phase ϕ=(87±2)∘, while the range parameter is not well-constrained. The striking behavior of the GRAAL data on the beam asymmetry in the threshold region suggests that a narrow proton-η′ resonance might exist. However, the scattering length was found to be relatively insensitive to the possible existence of this narrow resonance.
Published: 2018

6. Scalar isoscalar mesons and the scalar glueball from radiative $J/\psi$ decays

Author: U. Thoma, I. Denisenko, Eberhard Klempt, and A. V. Sarantsev
Subjects: Physics, Nuclear and High Energy Physics, Particle physics, Meson, Octet, 010308 nuclear & particles physics, Glueball, Isoscalar, Scalar (mathematics), High Energy Physics::Phenomenology, Nuclear Theory, 01 natural sciences, lcsh:QC1-999, High Energy Physics - Phenomenology, Amplitude, 0103 physical sciences, Radiative transfer, High Energy Physics::Experiment, Singlet state, 010306 general physics, Nuclear Experiment, lcsh:Physics
Abstract: A coupled-channel analysis of BESIII data on radiative $J/\psi$ decays into $\pi\pi$, $K\bar K$, $\eta\eta$ and $\omega\phi$ 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 $\Gamma= 370$\er$50^{+30}_{-20}$ {\rm MeV}, its yield in radiative $J/\psi$ decays to ($5.8\pm 1.0)\,10^{-3}$., Comment: 11 pages, 4 figures
Published: 2021

7. Measurement of the helicity asymmetry E for the reaction $$ \gamma p\rightarrow \pi ^0 p$$

Author: H. Schmieden, D. E. Bayadilov, A. B. Gridnev, Mariana Nanova, T. Rostomyan, M. Gottschall, M. Urban, V. Sokhoyan, D. Walther, M. Dieterle, T. Seifen, Ch. Hammann, A. Thiel, A. Winnebeck, Frank Frommberger, Matthew Lang, M. Kube, I. Keshelashvili, J. Hannappel, A. V. Anisovich, Jörg H. Müller, Jens Hartmann, V. Crede, Lilian Witthauer, Ulrich Wiedner, U. Thoma, P. Mahlberg, G. Reicherz, Frank Klein, V. Metag, Y. Wunderlich, K. Koop, K. Spieker, A. V. Sarantsev, A. Wilson, M. Bichow, Ch. Honisch, Ch. Schmidt, S. Friedrich, K. Makonyi, R. Beck, H. Dutz, K.-Th. Brinkmann, H. van Pee, P. Klassen, H. Eberhardt, D. Werthmüller, M. Grüner, S. Kammer, F. Dietz, R. Ewald, F. Afzal, H. Kalinowsky, E. Gutz, D. Piontek, I. V. Lopatin, T. C. Jude, Wolfgang Hillert, Ch. Wendel, D. Elsner, R. W. Novotny, Ph. Hoffmeister, V. A. Nikonov, J. Müllers, Eberhard Klempt, B. Krusche, W. Meyer, and K. Fornet-Ponse
Subjects: Nuclear physics, Physics, Nuclear and High Energy Physics, Photon, media_common.quotation_subject, Hadron, Bremsstrahlung, Nuclear fusion, Electron, Photon energy, Helicity, Asymmetry, media_common
Abstract: A measurement of the double-polarization observable E for the reaction $$\gamma p\rightarrow \pi ^0 p$$ γ p → π 0 p is reported. The data were taken with the CBELSA/TAPS experiment at the ELSA facility in Bonn using the Bonn frozen-spin butanol (C$$_4$$ 4 H$$_9$$ 9 OH) target, which provided longitudinally-polarized protons. Circularly-polarized photons were produced via bremsstrahlung of longitudinally-polarized electrons. The data cover the photon energy range from $$E_\gamma =600$$ E γ = 600 to 2310 MeV and nearly the complete angular range. The results are compared to and have been included in recent partial wave analyses.
Published: 2021

8. Observation of the pη′ Cusp in the New Precise Beam Asymmetry Σ Data for γp→pη

Author: Cbelsa, F. Afzal, L Richter, S. Ciupka, U-G Meißner, V. Metag, W. Meyer, M. Grüner, K. Koop, T. Seifen, Lilian Witthauer, H. Kalinowsky, Matthew Lang, D. Piontek, N. Stausberg, M. Urban, I. V. Lopatin, A. V. Sarantsev, T. C. Jude, Frank Frommberger, M. Becker, B. Mitlasóczki, H. Schmieden, M. Dieterle, V. Sokhoyan, H. van Pee, D. E. Bayadilov, P. Klassen, K. Spieker, K. Nikonov, B. Krusche, A. B. Gridnev, Mariana Nanova, B. Salisbury, Wolfgang Hillert, J. Hannappel, C. Sowa, J. Hoff, E. Gutz, Ch. Honisch, J. Schultes, H. Dutz, G. Urff, Ch. Schmidt, Y. Wunderlich, Ulrich Wiedner, Frank Klein, V. Crede, U. Thoma, D. Elsner, S. Friedrich, A. Wilson, R. W. Novotny, Ph. Hoffmeister, A. Thiel, V. Novinskiy, P. Mahlberg, A. V. Anisovich, Francesco Messi, I. Keshelashvili, Ch. Wendel, F. Kalischewski, K.-T. Brinkmann, T. Triffterer, P. Kroenert, G. Reicherz, D. Walther, Jörg H. Müller, Jens Hartmann, D. Rönchen, T. Rostomyan, M. Gottschall, E. Blanke, D. Schaab, R. Beck, Ch. Hammann, A. Winnebeck, J. Müllers, Eberhard Klempt, and V. A. Nikonov
Subjects: Physics, Photon, Meson, media_common.quotation_subject, Partial wave analysis, Nuclear Theory, Solid angle, General Physics and Astronomy, Observable, Polarization (waves), 01 natural sciences, Asymmetry, Nuclear physics, 0103 physical sciences, Physics::Accelerator Physics, Nuclear Experiment, 010306 general physics, Nucleon, media_common
Abstract: Data on the beam asymmetry Σ in the photoproduction of η mesons off protons are reported for tagged photon energies from 1130 to 1790 MeV (mass range from W=1748 MeV to W=2045 MeV). The data cover the full solid angle that allows for a precise moment analysis. For the first time, a strong cusp effect in a polarization observable has been observed that is an effect of a branch-point singularity at the pη^{'} threshold [E_{γ}=1447 MeV (W=1896 MeV)]. The latest BnGa partial wave analysis includes the new beam asymmetry data and yields a strong indication for the N(1895)1/2^{-} nucleon resonance, demonstrating the importance of including all singularities for a correct determination of partial waves and resonance parameters.
Published: 2020

9. $$\varLambda $$ and $$\varSigma $$ Excitations and the Quark Model

Author: L. Tiator, U. Thoma, Volker D. Burkert, Eberhard Klempt, and Ron L. Workman
Subjects: Physics, Nuclear and High Energy Physics, Particle physics, 010308 nuclear & particles physics, Hadron, Spectrum (functional analysis), Quark model, Hyperon, Structure (category theory), 01 natural sciences, 0103 physical sciences, Nuclear fusion, Singlet state, 010306 general physics
Abstract: The spectrum of$$\varLambda $$Λand$$\varSigma $$Σexcitations is reviewed taking into account (nearly) all hyperon resonances which were seen in early analyses or in one of the recent partial-wave analyses. The spectrum is compared with the old Isgur–Karl model and the Bonn model. These models allows us to discuss the SU(3) structure of the observed resonances. The SU(3) decomposition is compared with SU(6) relations between the different decay modes. Seven$$\varLambda $$Λstates are proposed to be classified as SU(3) singlet states. The hyperon spectrum is compared with the spectrum ofNand$$\varDelta $$Δresonances.
Published: 2020

10. Hyperon III: $$K^{-}p - \pi \varSigma $$ coupled-channel dynamics in the $$\varLambda (1405)$$ mass region

Author: Eberhard Klempt, A. V. Sarantsev, Volker D. Burkert, A. V. Anisovich, U. Thoma, R. A. Schumacher, and V. A. Nikonov
Subjects: Physics, Nuclear and High Energy Physics, Particle physics, 010308 nuclear & particles physics, Isoscalar, Hadron, Hyperon, Charge (physics), State (functional analysis), 01 natural sciences, 0103 physical sciences, Atom, Singlet state, 010306 general physics, Crystal Ball
Abstract: Low-energy data on the three charge states in $$\gamma p \rightarrow K^+(\varSigma \pi )$$ γ p → K + ( Σ π ) from CLAS at JLab, on $$K^-p\rightarrow \pi ^0\pi ^0\varLambda $$ K - p → π 0 π 0 Λ and $$\pi ^0\pi ^0\varSigma $$ π 0 π 0 Σ from the Crystal Ball at BNL, bubble chamber data on $$K^-p\rightarrow \pi ^-\pi ^+\pi ^{\pm }\varSigma ^{\mp }$$ K - p → π - π + π ± Σ ∓ , low-energy total cross sections on $$K^-$$ K - induced reactions, and data on the $$K^-p$$ K - p atom are fitted with the BnGa partial-wave-analysis program. We find that the data can be fitted well with just one isoscalar spin-1/2 negative-parity pole, the $$\varLambda (1405)$$ Λ ( 1405 ) , and background contributions. In a fit with one isocsalar state, the $$\varLambda (1405)$$ Λ ( 1405 ) structure can be determined as a dominantly SU(3) singlet state. A fit with two isoscalar singlet states, with imposed properties of the low-mass state, is, however, also not incompatible with data.
Published: 2020

11. Are the XYZ states unconventional states or conventional states with unconventional properties?

Author: Eberhard Klempt and Christoph Hanhart
Subjects: Quark, Physics, Nuclear and High Energy Physics, Particle physics, Meson, High Energy Physics::Lattice, Quark model, Nuclear Theory, High Energy Physics::Phenomenology, FOS: Physical sciences, Astronomy and Astrophysics, Atomic and Molecular Physics, and Optics, High Energy Physics - Experiment, Interpretation (model theory), High Energy Physics - Phenomenology, High Energy Physics - Experiment (hep-ex), High Energy Physics - Phenomenology (hep-ph), High Energy Physics::Experiment, ddc:530, Nuclear Experiment
Abstract: We discuss three possible scenarios for the interpretation of mesons containing a heavy quark and its antiquark near and above the first threshold for a decay into a pair of heavy mesons in a relative $S$--wave. View I assumes that these thresholds force the quark potential to flatten which implies that while in these energy ranges molecular states may be formed there should not be any quark--anti-quark states above these thresholds. View II assumes that the main part of the interaction between two mesons is due to the poles which originate from the $Q\bar Q$ interaction. The properties of the $Q\bar Q$ mesons are strongly influenced by opening thresholds but the number of states is given by the quark model. In View III, both types of mesons are admitted also near and above the open flavor thresholds: $Q\bar Q$ mesons and dynamically generated mesons. Experimental consequences of these different views are discussed., Comment: 15 pages, 5 figures
Published: 2020

12. The Λ(1405) with one pole

Author: Eberhard Klempt
Subjects: Physics, Range (particle radiation), QC1-999, Atomic physics, Resonance (particle physics)
Abstract: The Λ(1405)1/2-resonance is discussed and a fit of the Bonn-Gatchina (BnGa) partial-wave- analysis group is presented to data relevant for this resonance. In the Σπ-NKcoupled channel system, no Σ pole and only one Λ pole in the mass range from the Σπthreshold to 1500 MeV is required to get a good description of the data.
Published: 2020

13. Hyperon I: Partial-wave amplitudes for K-p scattering

Author: V. A. Nikonov, A. V. Anisovich, M. A. Matveev, A. V. Sarantsev, U. Thoma, and Eberhard Klempt
Subjects: Physics, Nuclear and High Energy Physics, Particle physics, 010308 nuclear & particles physics, Scattering, Hadron, Hyperon, FOS: Physical sciences, Resonance, Lambda, digestive system, 01 natural sciences, digestive system diseases, Amplitude, Hadron spectroscopy, 0103 physical sciences, Nuclear Experiment (nucl-ex), Nuclear Experiment, 010306 general physics, Legendre polynomials
Abstract: Early data on $K^-$ induced reactions off protons are collected and used in a coupled-channel partial wave analysis (PWA). Data which had been published in the form of Legendre coefficients are included in the PWA. In a {\it primary} fit using 3* and 4* resonances only, we observe some significant discrepancies with the data. In a systematic search for new $\Lambda$ and $\Sigma$ hyperon resonances, additional candidates are found. The significance of the known and of the additional resonances is evaluated. Seventeen resonances listed with 1* or 2* and one resonance listed with 3* in the Review of Particle Properties cannot be confirmed, five new hyperons are suggested. The partial-wave amplitudes deduced in this analysis are compared to those from other analyses., Comment: 28 pages, 27 figures, 9 Tables
Published: 2019

14. Hyperon II: Properties of excited hyperons

Author: V. A. Nikonov, A. V. Sarantsev, M. A. Matveev, A. V. Anisovich, U. Thoma, and Eberhard Klempt
Subjects: Physics, Nuclear and High Energy Physics, Particle physics, Quark model, Hadron, Hyperon, FOS: Physical sciences, Lambda, Omega, Excited state, Mass spectrum, High Energy Physics::Experiment, Singlet state, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract: We report properties of $\Lambda$ and $\Sigma$ hyperon resonances formed in $K^-$ induced reactions. Special emphasis is laid on the analysis of the three-body final states $2\pi^0\Lambda$ and $2\pi^0\Sigma$ and of the quasi-two-body final states $\pi\Lambda(1520)$, $\bar K\Delta(1232)$, $\pi\Sigma(1385)$, $\bar K^*N$, and $\omega\Lambda$. We give pole positions of $\Lambda$ and $\Sigma$ hyperon resonances and transition residues from the $K^-p$ initial to various final states as well as Breit-Wigner masses and widths and decay branching ratios. Twenty resonances and "bumps" reported in the Review of Particle Physics are not required in our fits, evidence for five new resonances is reported. The observed mass spectrum is compared to the spectrum calculated in the Bonn quark model. Three spin doublets, six $\Lambda$ hyperons, are tentatively assigned to the SU(3) singlet system., Comment: 18 pages, 10 Figures, 3 Tables
Published: 2019

15. Photon beam asymmetry Σ in the reaction γ→p→pω for E= 1.152 to 1.876 GeV

Author: G. Khachatryan, W. Kim, M. Battaglieri, N. K. Walford, G. Niculescu, L. Lanza, Michael Paolone, M. Bashkanov, S. Adhikari, H. Avakian, F. X. Girod, W. J. Briscoe, Laura Clark, B. McKinnon, P. Lenisa, T. Cao, M. Ungaro, I. J. D. MacGregor, F. Sabatié, I. I. Strakovsky, H. Voskanyan, A. Kim, E. De Sanctis, V. A. Nikonov, A. Deur, E. Pasyuk, J. W. Price, N. Dashyan, C. Gleason, G. Rosner, K. Hicks, V. Mokeev, P. Nadel-Turonski, V. Batourine, I. Bedlinskiy, D. I. Sober, S. Strauch, V. Crede, William Brooks, Dustin Keller, M. Defurne, Y. Ghandilyan, D. P. Watts, Barry Ritchie, Brian Raue, Alessandro Rizzo, C. Hanretty, H. Egiyan, E. Golovatch, R. Dupre, R. A. Montgomery, A. Celentano, R. W. Gothe, M. Khachatryan, Sylvester Joosten, B. S. Ishkhanov, G. Charles, Michael Wood, J. Ball, K. Hafidi, W. Phelps, H. S. Jo, A. V. Sarantsev, G. Ciullo, Y. Prok, D. I. Glazier, D. S. Carman, A. Simonyan, O. Cortes, N. A. Baltzell, C. Munoz Camacho, Nikos Sparveris, F. J. Klein, M. Ripani, M. Contalbrigo, Z. E. Meziani, E. L. Isupov, S. Niccolai, D. G. Jenkins, M. Osipenko, K. A. Griffioen, R. Paremuzyan, Eberhard Klempt, S. Boiarinov, N. Markov, V. P. Kubarovsky, A. Movsisyan, R. De Vita, Nicholas M. Harrison, O. Pogorelko, Gerard Gilfoyle, J. Zhang, S. M. Hughes, X. Wei, S. Pisano, D. Sokhan, I. Stankovic, A. V. Anisovich, C. A. Meyer, Z. Akbar, G. V. Fedotov, I. Niculescu, C. Salgado, P. L. Cole, A. I. Ostrovidov, K. Park, R. A. Schumacher, D. G. Ireland, H. Jiang, H. Hakobyan, S. Anefalos Pereira, Volker D. Burkert, A. S. Biselli, L. El Fassi, K. P. Adhikari, S. Stepanyan, E. Munevar, L. A. Net, Avraham Klein, Y. G. Sharabian, J. A. Fleming, Iu. Skorodumina, D. Heddle, G. Hollis, P. Eugenio, M. Taiuti, P. Collins, S. Procureur, K. L. Giovanetti, A. El Alaoui, Y. Ilieva, Nicholas Zachariou, A. Filippi, M. Khandaker, K. Livingston, M. Hattawy, D. Protopopescu, Z. W. Zhao, E. Voutier, Chaden Djalali, Michael Dugger, T. Mineeva, F. Cao, D. Adikaram, M. Guidal, G. D. Smith, M. Holtrop, Taya Chetry, and Sergey Kuleshov
Subjects: Physics, Nuclear and High Energy Physics, Photon, Meson, Proton, 010308 nuclear & particles physics, Partial wave analysis, Bremsstrahlung, Photon energy, 01 natural sciences, Nuclear physics, Pomeron, 0103 physical sciences, Nuclear Experiment, 010306 general physics, Nucleon
Abstract: Photon beam asymmetry Σ measurements for ω photoproduction in the reaction γ → p → ω p are reported for photon energies from 1.152 to 1.876 GeV. Data were taken using a linearly-polarized tagged photon beam, a cryogenic hydrogen target, and the CLAS spectrometer in Hall B at Jefferson Lab. The measurements obtained markedly increase the size of the database for this observable, extend coverage to higher energies, and resolve discrepancies in previously published data. Comparisons of these new results with predictions from a chiral-quark-based model and from a dynamical coupled-channels model indicate the importance of interferences between t-channel meson exchange and s- and u-channel contributions, underscoring sensitivity to the nucleon resonances included in those descriptions. Comparisons with the Bonn–Gatchina partial-wave analysis indicate the Σ data reported here help to fix the magnitudes of the interference terms between the leading amplitudes in that calculation (Pomeron exchange and the resonant portion of the J P = 3 / 2 + partial wave), as well as the resonant portions of the smaller partial waves with J P = 1 / 2 − , 3 / 2 − , and 5 / 2 + .
Published: 2017

16. Evidence for Δ(2200)7/2− from photoproduction and consequence for chiral-symmetry restoration at high mass

Author: A. V. Sarantsev, A. V. Anisovich, Volker D. Burkert, S. Strauch, Jens Hartmann, Eugene Pasyuk, Eberhard Klempt, V. A. Nikonov, and U. Thoma
Subjects: Physics, Nuclear and High Energy Physics, Particle physics, Chiral symmetry, 010308 nuclear & particles physics, Partial wave analysis, Hadron, Degenerate energy levels, Resonance, Parity (physics), 01 natural sciences, lcsh:QC1-999, Baryon, Photoproduction, 0103 physical sciences, High mass, Partial-wave analysis, Atomic physics, 010306 general physics, Baryon resonance, lcsh:Physics
Abstract: We report a partial-wave analysis of new data on the double-polarization variable E for the reactions γ p → π + n and γ p → π 0 p and of further data published earlier. The analysis within the Bonn–Gatchina (BnGa) formalism reveals evidence for a poorly known baryon resonance, the one-star Δ ( 2200 ) 7 / 2 − . This is the lowest-mass Δ ⁎ resonance with spin-parity J P = 7 / 2 − . Its mass is significantly higher than the mass of its parity partner Δ ( 1950 ) 7 / 2 + which is the lowest-mass Δ ⁎ resonance with spin-parity J P = 7 / 2 + . It has been suggested that chiral symmetry might be restored in the high-mass region of hadron excitations, and that these two resonances should be degenerate in mass. Our findings are in conflict with this prediction.
Published: 2017

17. First Measurements of the Double-Polarization Observables F , P , and H in ω Photoproduction off Transversely Polarized Protons in the N* Resonance Region

Author: Eberhard Klempt, O. Cortes, C. Hanretty, K. A. Griffioen, M. Ungaro, V. A. Nikonov, X. Wei, B. S. Ishkhanov, O. Soto, C. D. Keith, S. Strauch, G. Khachatryan, F. X. Girod, M. Osipenko, A. D'Angelo, Eugene Pasyuk, H. S. Jo, A. El Alaoui, W. J. Briscoe, Y. Ilieva, Aditya R. Khanal, Dustin Keller, L. Barion, F. Sabatié, I. I. Strakovsky, L. Guo, Alessandro Rizzo, A. V. Anisovich, L. Lanza, J. Brock, V. Mokeev, E. L. Isupov, Nicholas Zachariou, K Nakayama, M. C. Kunkel, P. Nadel-Turonski, Rong Wang, R. De Vita, A. Deur, R. A. Schumacher, Michael Wood, P. Lenisa, W. Phelps, Barry Ritchie, S. Boiarinov, K. Hafidi, G. Ciullo, Y. Prok, Iu. Skorodumina, S Niccolai, P. Eugenio, W. Kim, G. Niculescu, D. S. Carman, W. K. Brooks, I. Bedlinskiy, C. A. Meyer, D. Payette, K. Livingston, Sylvester Joosten, G. Rosner, H. Egiyan, Andrea Celentano, T. B. Hayward, J. Pierce, Jie Zhang, S. Adhikari, Friedrich Klein, D. G. Jenkins, M. Taiuti, K. P. Adhikari, Brian Raue, D. P. Watts, D. Marchand, Y. G. Sharabian, A. Movsisyan, S. Diehl, M. Ripani, C. Salgado, C. Carlin, S. Fegan, M. L. Kabir, A. V. Sarantsev, M. Battaglieri, N. Tyler, B. Duran, V. P. Kubarovsky, E. Voutier, J. A. Tan, U. Shrestha, V. Crede, D. Riser, Chaden Djalali, O. Pogorelko, M. Khachatryan, Michael Dugger, T. Mineeva, H. Avakian, E. Golovatch, A Fradi, R. Dupre, H. Voskanyan, Nikolaos Sparveris, F. Cao, P. Roy, N C Wei, N. K. Walford, R. A. Montgomery, M. Guidal, E. De Sanctis, N. Dashyan, A. Kim, P. Chatagnon, I. J. D. MacGregor, Michael Paolone, M. Holtrop, M. Hattawy, R. W. Gothe, M Ehrhart, K. Hicks, Luciano Pappalardo, S. Park, Taya Chetry, M. Contalbrigo, G. Angelini, Sergey Kuleshov, D. G. Meekins, L. El Fassi, A. I. Ostrovidov, D. G. Ireland, Volker D. Burkert, A. S. Biselli, M. Khandaker, B. McKinnon, D. Heddle, P. L. Cole, M. L. Seely, B. Torayev, Feng Huang, R. Paremuzyan, Sandra K. Johnston, D. Protopopescu, Z. W. Zhao, Nicholas M. Harrison, Gerard Gilfoyle, D. Sokhan, A. Filippi, and C. Munoz Camacho
Subjects: Physics, Photon, Spectrometer, Proton, Linear polarization, media_common.quotation_subject, Nuclear Theory, General Physics and Astronomy, Resonance, Polarization (waves), 01 natural sciences, Asymmetry, Nuclear physics, 0103 physical sciences, Physics::Accelerator Physics, Nuclear Experiment, 010306 general physics, Nucleon, media_common
Abstract: First measurements of double-polarization observables in ω photoproduction off the proton are presented using transverse target polarization and data from the CEBAF Large Acceptance Spectrometer (CLAS) FROST experiment at Jefferson Lab. The beam-target asymmetry F has been measured using circularly polarized, tagged photons in the energy range 1200-2700 MeV, and the beam-target asymmetries H and P have been measured using linearly polarized, tagged photons in the energy range 1200-2000 MeV. These measurements significantly increase the database on polarization observables. The results are included in two partial-wave analyses and reveal significant contributions from several nucleon (N^{*}) resonances. In particular, contributions from new N^{*} resonances listed in the Review of Particle Properties are observed, which aid in reaching the goal of mapping out the nucleon resonance spectrum.
Published: 2019

18. Lebendige Sonne, Ursprung des Lebens

Author: Eberhard Klempt
Abstract: Die Sonne ist das Zentrum unseres Sonnensystems, sie spendet die fur das Leben auf der Erde notwendige Energie. Diese wird im Inneren der Sonne durch stufenweises Verbrennen von Wasserstoff zu Helium bei Temperaturen um 15 Millionen Grad gewonnen. Dabei entstehen solare Neutrinos, die einen Blick in das Innere der Sonne gestatten. Ihre Anzahl entsprach nicht der Erwartung; daraus ergab sich der erste Hinweis darauf, dass Neutrinos nicht – wie Photonen – masselos sind. An der Oberflache der Sonne herrschen Temperaturen von rund 5700 Grad Celsius. Seit etwa 4,57 Milliarden Jahren scheint die Sonne, und sie wird das noch mindestens weitere rund funf Milliarden Jahre tun. Insgesamt hat sie fur zehn bis dreizehn Milliarden Jahre Brennstoff. Geht dieser zur Neige, wird die Sonne jedoch nicht mal eben so abkuhlen: Sie wird sich zu einem Roten Riesen aufblahen, der die inneren Planeten verschlingt.
Published: 2019

19. Einleitung

Author: Eberhard Klempt
Published: 2019

20. Beam-target helicity asymmetry E in K0Λ and K0Σ0 photoproduction on the neutron

Author: P. Lenisa, M. Ungaro, D. G. Ireland, C. A. Meyer, R. Dupre, V. Crede, C.D. Bass, V. A. Nikonov, M. Battaglieri, P. Chatagnon, G. V. Fedotov, R. A. Montgomery, Ron L. Workman, R. Paremuzyan, R. A. Schumacher, C. S. Whisnant, K. P. Adhikari, A. Fradi, M. Osipenko, D. G. Jenkins, Nicholas M. Harrison, N. Markov, Martin K. Mayer, K. A. Griffioen, I. Zonta, I. J. D. MacGregor, A. Kim, H. Hakobyan, M. Khachatryan, D. Sokhan, H. S. Jo, Tim O'Connell, D. Marchand, S. Diehl, M. Bashkanov, B. McKinnon, A. I. Ostrovidov, K. Park, V. Mokeev, G. Khachatryan, L. Lanza, Eberhard Klempt, P. Collins, S. Niccolai, F. X. Girod, M. Contalbrigo, Sandra K. Johnston, P. Eugenio, T. Chetry, Volker D. Burkert, A. S. Biselli, Pawel Nadel-Turonski, M. Mirazita, J. Zhang, Rong Wang, J. W. Price, Alessandro Rizzo, S. Strauch, Iu. Skorodumina, C. Hanretty, George Davey Smith, M. Taiuti, C. Djalali, J. A. Tan, E. Golovatch, Y. G. Sharabian, M. Lowry, G. Charles, K. L. Giovanetti, I. Bedlinskiy, M. Rehfuss, K. Hicks, S. Adhikari, M. L. Kabir, M. Ehrhart, F. Sabatié, Andreas Klein, V. Laine, F. Cao, D. Adikaram, M. Guidal, W. Kim, Larry Weinstein, Z. Akbar, G. Rosner, P. Peng, C. Munoz Camacho, M. H. Wood, M. Hattawy, G. Niculescu, J. A. Fleming, I. I. Strakovsky, M. Holtrop, A. Filippi, A. D'Angelo, M. Ripani, Y. Ghandilyan, Carlos A. Salgado, B. A. Clary, A. M. Sandorfi, B. S. Ishkhanov, M. Khandaker, D. I. Sober, A. Deur, Hong Lu, Michael Paolone, D. Ho, S. Fegan, A. Celentano, R. W. Gothe, D. Heddle, Maxime Defurne, E. L. Isupov, W. Gohn, S. Boiarinov, R. De Vita, T. Kageya, L. El Fassi, N. K. Walford, R. G. Fersch, Frank Klein, P. L. Cole, Z. W. Zhao, Dustin Keller, G. Ciullo, J. P. Ball, Y. Prok, D. S. Carman, Nikos Sparveris, X. Wei, K. Hafidi, E. Voutier, A. Movsisyan, Yordanka Ilieva, L. Barion, V. P. Kubarovsky, D. Riser, A. El Alaoui, Nicholas Zachariou, O. Pogorelko, K. Livingston, H. Voskanyan, D. Protopopescu, W. J. Briscoe, E. Pasyuk, D. P. Watts, H. Egiyan, A. V. Sarantsev, and S. Chandavar
Subjects: Physics, Strange quark, 010308 nuclear & particles physics, media_common.quotation_subject, Nuclear Theory, Quark model, Hyperon, 01 natural sciences, Helicity, Asymmetry, Pseudoscalar meson, Nuclear physics, 13. Climate action, Isospin, 0103 physical sciences, Neutron, Nuclear Experiment, 010306 general physics, media_common
Abstract: We report the first measurements of the E beam-target helicity asymmetry for the γn→K0Λ and K0Σ0 channels in the energy range 1.70≤W≤2.34 GeV. The CLAS system at Jefferson Lab uses a circularly polarized photon beam and a target consisting of longitudinally polarized solid molecular hydrogen deuteride with low background contamination for the measurements. The multivariate analysis method boosted decision trees is used to isolate the reactions of interest. Comparisons with predictions from the KaonMAID, SAID, and Bonn-Gatchina models are presented. These results will help separate the isospin I=0 and I=1 photocoupling transition amplitudes in pseudoscalar meson photoproduction.
Published: 2018

21. Explodierende Vielfalt : Wie Komplexität entsteht

Author: Eberhard Klempt and Eberhard Klempt
Subjects: Physics, Astronomy, Engineering, Mathematics, Life sciences, Science, Social sciences, Humanities
Abstract: Verstehen wir die Welt? Wie ist unsere Welt entstanden? Warum gibt es so viel Materie und so wenig Antimaterie? Wie bildeten sich die weiträumigen Strukturen in unserem Universum? Und wie entstanden aus der unbelebten Materie die ersten reproduktionsfähigen Lebewesen? Welcher Anpassungsdruck erzeugte die Artenvielfalt und letztlich die Hominiden? Wie entwickelten sich Bewusstsein, Kreativität, Religion? In dem vorliegenden Buch beantworten herausragende Wissenschaftler diese und viele weitere spannende Fragen und erklären, wie aus einfachen Anfängen und simplen Regeln immer wieder komplizierte Strukturen entstanden sind. Diese sogenannte Selbstorganisation wird an Beispielen aus den verschiedensten Disziplinen demonstriert – sei es bei der Geburt des Universums, auf der Ebene der Quarks und der Atome, bei der Entstehung des Lebens und bei seiner Ausdifferenzierung in die Vielzahl der Lebensformen bis hin zum Menschen selbst, mit seinen kulturell und wissenschaftlich immer höher entwickelten Gesellschaften. Interessierte Leser können mit Hilfe dieses Buches nachvollziehen, mit welchen Erkenntnissen und Thesen die Wissenschaft heute erklärt, wie die Natur mit einfachen Grundbausteinen und Gesetzen solch komplexe Gefüge geschaffen hat.
Published: 2019

22. N⁎ decays to Nω from new data on γp→ωp

Author: H. Schmieden, A. V. Sarantsev, U. Thoma, V. Crede, A. V. Anisovich, H. Eberhardt, A. Wilson, Eberhard Klempt, V. A. Nikonov, and I. Denisenko
Subjects: Physics, Nuclear and High Energy Physics, Photon, 010308 nuclear & particles physics, media_common.quotation_subject, Partial wave analysis, Polarization (waves), 7. Clean energy, 01 natural sciences, Asymmetry, Helicity, lcsh:QC1-999, Nuclear physics, Pion, 0103 physical sciences, Spin density, 010306 general physics, Nuclear Experiment, Beam (structure), lcsh:Physics, media_common
Abstract: Data on the reaction γ p → ω p with ω → π 0 γ , taken with unpolarized or polarized beams in combination with an unpolarized or polarized proton-target, were analyzed within the Bonn–Gatchina (BnGa) partial wave analysis. Differential cross sections, several spin density matrix elements, the beam asymmetry Σ, the normalized helicity difference E, and the correlation G between linear photon and longitudinal target polarization were included in a large data base on pion and photo-induced reactions. The data on ω photoproduction are used to determine twelve N ⁎ → N ω branching ratios; most of these are determined for the first time.
Published: 2016
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23. First measurement of the polarization observable E in the p→(γ→,π+)n reaction up to 2.25 GeV

Author: I. Zonta, William Brooks, X. Wei, P. Lenisa, K. Livingston, D. P. Watts, Friedrich Klein, A. V. Sarantsev, D. Rönchen, P. Nadel-Turonski, Z. W. Zhao, Eberhard Klempt, W. Gohn, F. Sabatié, R. A. Badui, H. Y. Lu, I. Niculescu, I. I. Strakovsky, B. A. Raue, R. A. Schumacher, A. El Alaoui, Barry Ritchie, J. W. Price, A. Deur, Nicholas Zachariou, K. A. Griffioen, S. Chandavar, A. V. Anisovich, L. Guo, M. Ungaro, M. Ripani, R. W. Gothe, Michael Döring, T. A. Forest, S. Stepanyan, E. Munevar, Avraham Klein, Iu. Skorodumina, P. Eugenio, C. I. Moody, M. Taiuti, V. Crede, V. A. Nikonov, Latifa Elouadrhiri, G. Khachatryan, C. A. Meyer, G.V. O'Rielly, A. Trivedi, K. Joo, G. V. Fedotov, Andrea Celentano, Andrew Puckett, R. A. Montgomery, A. Kim, E. Golovatch, R. Dupre, S. Procureur, D. Keller, R. De Vita, D. Protopopescu, M. Contalbrigo, D. G. Jenkins, S. Pozdniakov, I. Bedlinskiy, K. P. Adhikari, N. Benmouna, F. X. Girod, J. Brock, H. S. Jo, N. Compton, Jian Zhang, C. Carlin, A. Filippi, Nikolaos Sparveris, N. Gevorgyan, W. Kim, S. Strauch, D. S. Carman, Victor Mokeev, G. Niculescu, D. Ho, K. Park, L. Colaneri, M. Khandaker, John Phillips, A. Simonyan, E. Seder, N. Markov, S. Pisano, N. K. Walford, M. Hattawy, D. I. Glazier, E. Voutier, T. Cao, A. Fradi, O. Pogorelko, D. G. Meekins, Diane Schott, G. Rosner, I. J. D. MacGregor, A. I. Ostrovidov, M. Osipenko, D. G. Ireland, H. Moutarde, M. Battaglieri, Y. Ghandilyan, H. Jiang, B. S. Ishkhanov, Volker D. Burkert, S. E. Kuhn, A. S. Biselli, K. L. Giovanetti, J. A. Fleming, L. El Fassi, P. Peng, Hovanes Egiyan, Chaden Djalali, Michael Dugger, Hrachya Hakobyan, Y. Ilieva, C. Munoz Camacho, R. Tucker, Ron L. Workman, P. L. Cole, B. McKinnon, L. A. Net, S. Fegan, Eugene Pasyuk, S. Anefalos Pereira, Y. G. Sharabian, W. Phelps, V. Batourine, M. L. Seely, D. Sokhan, E. De Sanctis, C. D. Keith, J. P. Ball, Y. Prok, D. I. Sober, A. Rizzo, S. Niccolai, C. Hanretty, V. Sytnik, N. Harrison, A. Movsisyan, N. Dashyan, P. Stoler, I. Senderovich, K. Hicks, G. Charles, P. Roy, D. Adikaram, M. Guidal, S. Joosten, G. D. Smith, M. Holtrop, H. Voskanyan, W. J. Briscoe, V. P. Kubarovsky, Annalisa D'Angelo, S. M. Hughes, Michael Wood, K. Hafidi, O. Cortes, E. L. Isupov, Ye Tian, Lorenzo Zana, and C. Salgado
Subjects: Physics, Nuclear physics, Nuclear and High Energy Physics, Particle physics, Photon, Pion, Meson, Bremsstrahlung, Observable, Photon energy, Nuclear Experiment, Multipole expansion, Nucleon
Abstract: First results from the longitudinally polarized frozen-spin target (FROST) program are reported. The double-polarization observable E, for the reaction (p) over right arrow((gamma) over right arrow, pi(+))n, has been measured using a circularly polarized tagged-photon beam, with energies from 0.35 to 2.37 GeV. The final-state pions were detected with the CEBAF Large Acceptance Spectrometer in Hall B at the Thomas Jefferson National Accelerator Facility. These polarization data agree fairly well with previous partial-wave analyses at low photon energies. Over much of the covered energy range, however, significant deviations are observed, particularly in the high-energy region where high-L multipoles contribute. The data have been included in new multipole analyses resulting in updated nucleon resonance parameters. We report updated fits from the Bonn-Gatchina, Jfilich-Bonn, and SAID groups. (C) 2015 The Authors. Published by Elsevier B.V.
Published: 2015

24. Measurement of double polarisation asymmetries in ω -photoproduction

Author: Frank Frommberger, V. Metag, F. Diez, M. Bichow, Ch. Hammann, T. Seifen, I. Jaegle, F. Kalischewski, D. Elsner, M. Kube, V. Crede, P. Drexler, A. Winnebeck, K. Fornet-Ponse, H. Schmieden, J. Müller, R. W. Novotny, B. Bantes, D. Walther, Ph. Hoffmeister, D. E. Bayadilov, K. Koop, U. Thoma, A. B. Gridnev, Mariana Nanova, S. Böse, A. Wilson, Yasser Maghrbi, H. Kalinowsky, Eberhard Klempt, H. Dutz, J. Hannappel, S. Runkel, H. Eberhardt, R. Ewald, Ulrich Wiedner, W. Meyer, St. Schaepe, V. A. Nikonov, T. Rostomyan, I. Keshelashvili, R. Schmitz, B. Krusche, Ch. Honisch, M. Grüner, Ch. Schmidt, A. Thiel, S. Friedrich, G. Reicherz, M. Gottschall, Friedrich Klein, Ch. Wendel, V. V. Sumachev, Wolfgang Hillert, R. Beck, Jens Hartmann, E. Gutz, S. Kammer, Th. Challand, Ch. Funke, K. Makonyi, Matthew Lang, K.-Th. Brinkmann, D. Kaiser, S. Reeve, H. van Pee, V. Kleber, D. Piontek, I. V. Lopatin, T. C. Jude, Yu. A. Beloglazov, A. V. Sarantsev, A. V. Anisovich, M. Urban, and V. Sokhoyan
Subjects: Physics, Nuclear and High Energy Physics, Photon, Meson, Partial wave analysis, Meson production, Resonance, Photon energy, Helicity, Omega, lcsh:QC1-999, Light mesons (SCB0), Nuclear physics, Baryon, Polarisation in interactions and scattering, Light mesons (SCB0), Nuclear Experiment, lcsh:Physics
Abstract: The first measurements of the beam-target-helicity-asymmetries $E$ and $G$ in the photoproduction of $\omega$-mesons off protons at the CBELSA/TAPS experiment are reported. $E$ ($G$) was measured using circularly (linearly) polarised photons and a longitudinally polarised target. $E$ was measured over the photon energy range from close to threshold ($E_\gamma = 1108$~MeV) to $E_\gamma = 2300$~MeV and $G$ at a single energy interval of $1108 < E_\gamma, Comment: 6 pages, 6 figures
Published: 2015
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25. New data on γ→p→→ηp with polarized photons and protons and their implications for N⁎ → Nη decays

Author: P. Klassen, V. Hannen, J. Herick, Reinhard Beck, Ch. Wendel, S. Kammer, Jens Hartmann, V. Metag, H. van Pee, F. Dietz, P. Mahlberg, Ch. Honisch, Ch. Schmidt, Th. Challand, S. Böse, T. C. Jude, H. Kalinowsky, M. Bichow, K. Koop, T. Rostomyan, M. Becker, I. Jaegle, G. Reicherz, A. Berlin, A. Käser, Friedrich Klein, M. Gottschall, D. Kaiser, A. Wilson, R. Schmitz, T. Seifen, R. Ewald, C. Rosenbaum, Yasser Maghrbi, F. Afzal, H. Dutz, O. Jahn, H. Eberhardt, D. Elsner, A. Thiel, R. W. Novotny, Ph. Hoffmeister, V. Crede, S. Goertz, A. V. Anisovich, J. Müller, H. Schmieden, D. E. Bayadilov, A. B. Gridnev, Mariana Nanova, M. Grüner, B. Roth, Frank Frommberger, Matthew Lang, S. Friedrich, K. Makonyi, Francesco Messi, B. Bantes, J. Hannappel, Wolfgang Hillert, M. Kube, E. Gutz, Ulrich Wiedner, M. Urban, V. Kleber, U. Thoma, V. Sokhoyan, F. Kalischewski, I. Keshelashvili, W. Meyer, J. Müllers, Eberhard Klempt, K. Fornet-Ponse, C. Funke, D. V. Novinski, Lilian Witthauer, Ch. Hammann, B. Krusche, P. Drexler, A. Winnebeck, V. A. Nikonov, M. Dieterle, K.-T. Brinkmann, Yu. A. Beloglazov, A. V. Sarantsev, D. Piontek, I. V. Lopatin, and D. Walther
Subjects: Physics, Nuclear physics, Nuclear and High Energy Physics, Photon, Meson, 010308 nuclear & particles physics, 0103 physical sciences, Polarization observables, Solid angle, 010306 general physics, Branching (polymer chemistry), Nucleon, 01 natural sciences
Abstract: The polarization observables T , E , P , H , and G in photoproduction of η mesons off protons are measured for photon energies from threshold to W = 2400 MeV (T), 2280 MeV (E), 1620 MeV ( P , H ), or 1820 MeV (G), covering nearly the full solid angle. The data are compared to predictions from the SAID, MAID, JuBo, and BnGa partial-wave analyses. A refit within the BnGa approach including further data yields precise branching ratios for the Nη decay of nucleon resonances. A Nη-branching ratio of 0.33 ± 0.04 for N ( 1650 ) 1 / 2 − is found, which reduces the large and controversially discussed Nη-branching ratio difference of the two lowest mass J P = 1 / 2 − -resonances significantly.
Published: 2020

26. Review of Particle Physics

Author: J Lesgourgues, Siegfried Bethke, C. Hanhart, P Eerola, Christian W. Bauer, F Takahashi, Oleg Zenin, A. de Gouvea, C. Grojean, O Buchmuller, Masaharu Tanabashi, P. de Jong, J. Erler, R Sekhar Chivukula, M Taševský, S.I. Eidelman, C. W. Walter, D J Miller, A. Piepke, Torbjörn Sjöstrand, Y Sumino, Orin I. Dahl, Herbert K. Dreiner, A Soffer, Chi Lin, Bogdan A. Dobrescu, S. M. Spanier, R E Mitchell, Marcela Carena, Manuella Vincter, Otmar Biebel, M Karliner, V. S. Lugovsky, Ren-Yuan Zhu, J. J. Beatty, C. Patrignani, A Pomarol, U Thoma, Kurtis F Johnson, N Varelas, William J. Marciano, David Milstead, Sw. Banerjee, Michael Doser, P Urquijo, A. Gurtu, A Bettini, Aneesh V. Manohar, L. S. Littenberg, Michael Syphers, Burkert, M C Gonzalez-Garcia, Ron L. Workman, Jamie Holder, German Valencia, Subir Sarkar, M Kenzie, Charles G Wohl, W. Fetscher, J Hisano, W Vogelsang, Th. Gutsche, Zoltan Ligeti, Thibault Damour, K Rabbertz, Marumi Kado, Sharma, G. Cowan, Klaus Mönig, Fabio Maltoni, C. L. Woody, Anatoli Romaniouk, A. Stahl, Michal Kreps, J Ellis, W-M. Yao, B C Allanach, J Anderson, Ken Ichi Hikasa, Eberhard Klempt, Keith A. Olive, V I Belousov, David H. Weinberg, J.J. Hernández-Rey, Meenakshi Narain, Younghoon Kwon, Andreas Ringwald, M O Wascko, K Trabelsi, E. J. Weinberg, R Yoshida, Jonas Rademacker, D. M. Asner, R A Ryutin, Paolo Molaro, C Lourengo, Peter Skands, Vorobyev, Wolfgang Walkowiak, S. B. Lugovsky, B. K. Heltsley, K. S. Lugovsky, Uli Katz, Daniel Tovey, George F. Smoot, Stephen R. Sharpe, S Heinemeyer, Brian D. Fields, H Ramani, Y Gershtein, R S Thorne, Ofer Lahav, K M Black, T Mannel, Timothy Gershon, Yoshinari Hayato, P. Schaffner, E. Blucher, G. Venanzoni, T Skwarnicki, Giancarlo D'Ambrosio, A J Schwartz, D J Robinson, G Rybka, Joey Huston, M S Sozzi, L.J. Rosenberg, L P Lellouch, Sophia L. Stone, U G Meißner, L. R. Wiencke, L Verde, S. Rolli, G. Dissertori, Augusto Ceccucci, S. T. Petcov, Matthias Neubert, Koji Nakamura, J. Beringer, E Pianori, W Zheng, G Zanderighi, Paul William Richardson, Daniel de Florian, Maksym Titov, C Lippmann, K Terashi, Y. Sakai, A Höcker, Ezhela, L. Tiator, Manuel Drees, A Pich, S Profumo, Gavin P. Salam, R. M. Barnett, J Schwiening, E C Aschenauer, Howard Baer, O. Schneider, Tony Gherghetta, P A Zyla, Jack Laiho, T Hyodo, Jonathan L. Rosner, B. Krusche, H J Gerber, Kate Scholberg, Stefan Roesler, Shoji Hashimoto, D Wands, G Aielli, A Holtkamp, Andrei Gritsan, Arnulf Quadt, A Freitas, Alessandro Cerri, U Egede, H. R. Gallagher, G. Gerbier, V A Khoze, S. R. Klein, B. N. Ratcliff, Y Makida, S. P. Wakely, Christoph Grab, Alberto Masoni, M Mikhasenko, Tony Liss, R. N. Cahn, A A Godizov, Paolo Nason, P. Nevski, T. Sumiyoshi, M D'Onofrio, A Lusiani, B. Foster, Thomas DeGrand, N. P. Tkachenko, Martin White, Douglas Scott, M Yokoyama, G P Zeller, M Ryskin, Petr Vogel, Christian Spiering, M A Bychkov, L. Garren, R. Kowalewski, John Terning, Claude Amsler, John Matthews, Y. Nir, A Hebecker, Mario Antonelli, M Ramsey-Musolf, Andreas Vogt, S L Zhu, Andrew R. Liddle, L Baudis, Debadi Chakraborty, Kaustubh Agashe, J Tanaka, S. Sánchez Navas, Howard E. Haber, Frank Krauss, M. C. Goodman, V A Petrov, Martin Grunewald, Fabio Sauli, D A Dwyer, R. G. Van de Water, M. Silari, John A. Peacock, S Willocq, T Shutt, Frank Zimmermann, Filip Moortgat, M Moskovic, Georg G. Raffelt, D. E. Groom, T. Basaglia, The George Washington University (GW), Thomas Jefferson National Accelerator Facility (Jefferson Lab), Florida State University [Tallahassee] (FSU), Helmholtz-Institut für Strahlen- und Kernphysik (HISKP), Rheinische Friedrich-Wilhelms-Universität Bonn, Institut für Kernphysik (IKP), Forschungszentrum Jülich GmbH | Centre de recherche de Juliers, Helmholtz-Gemeinschaft = Helmholtz Association-Helmholtz-Gemeinschaft = Helmholtz Association, University of Maryland [Baltimore], Università degli Studi di Roma Tor Vergata [Roma], University of Cambridge [UK] (CAM), Austrian Academy of Sciences (OeAW), INFN Frascati, Istituto Nazionale di Fisica Nucleare (INFN), Brookhaven National Laboratory [Upton, NY] (BNL), UT-Battelle, LLC-Stony Brook University [SUNY] (SBU), State University of New York (SUNY)-State University of New York (SUNY)-U.S. Department of Energy [Washington] (DOE), University of Oklahoma (OU), University of Louisville, Lawrence Berkeley National Laboratory [Berkeley] (LBNL), Universität Zürich [Zürich] = University of Zurich (UZH), Ohio State University [Columbus] (OSU), National Research Centre Kurchatov Institute, Istituto Nazionale di Fisica Nucleare, Sezione di Padova (INFN, Sezione di Padova), Ludwig-Maximilians-Universität München (LMU), University of Wisconsin Oshkosh (UWO), University of Chicago, Imperial College London, University of Virginia, Fermi National Accelerator Laboratory (Fermilab), CERN [Genève], University of Sussex, University of California (UC), Royal Holloway [University of London] (RHUL), State University of New York (SUNY Canton), Istituto Nazionale di Fisica Nucleare, Sezione di Milano (INFN), Istituto Nazionale di Fisica Nucleare, Sezione di Napoli (INFN, Sezione di Napoli), Institut des Hautes Études Scientifiques (IHES), IHES, Universidad Nacional de San Martin (UNSAM), Northwestern University [Evanston], University of Colorado [Boulder], University of Amsterdam [Amsterdam] (UvA), Yale University [New Haven], University of Liverpool, Universitätsklinikum Bonn (UKB), TKK Helsinki University of Technology (TKK), Monash university, Budker Institute of Nuclear Physics (BINP), Siberian Branch of the Russian Academy of Sciences (SB RAS), University of Illinois [Chicago] (UIC), University of Illinois System, King‘s College London, Departement Physik [ETH Zürich] (D-PHYS), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), University of Pittsburgh (PITT), Pennsylvania Commonwealth System of Higher Education (PCSHE), Tufts University [Medford], Rutgers University [Camden], Rutgers University System (Rutgers), University of Minnesota System, Stony Brook University [SUNY] (SBU), State University of New York (SUNY), Argonne National Laboratory [Lemont] (ANL), Departement Erdwissenschaften [ETH Zürich] (D-ERDW), Johns Hopkins University (JHU), Deutsches Elektronen-Synchrotron [Hamburg] (DESY), University College Dublin [Dublin] (UCD), Department of Condensed Matter Physics and Materials Science [TIFR] (CMPMS), Tata Institute for Fundamental Research (TIFR), Universitätsklinikum Tübingen - University Hospital of Tübingen, Eberhard Karls Universität Tübingen = Eberhard Karls University of Tuebingen, Laboratoire Capteurs et Architectures Electroniques (LCAE), Département Métrologie Instrumentation & Information (DM2I), Laboratoire d'Intégration des Systèmes et des Technologies (LIST (CEA)), Direction de Recherche Technologique (CEA) (DRT (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Technologique (CEA) (DRT (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Laboratoire d'Intégration des Systèmes et des Technologies (LIST (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Forschungszentrum Jülich GmbH, KEK (High energy accelerator research organization), The University of Tokyo (UTokyo), Heidelberg University, Universidad Autónoma de Madrid (UAM), Universitat de València (UV), Tohoku University [Sendai], University of Delaware [Newark], Michigan State University System, Tokyo Metropolitan University [Tokyo] (TMU), Gran Sasso Science Institute, INFN, Università degli Studi di Roma 'La Sapienza' = Sapienza University [Rome] (UNIROMA), Laboratoire de Physique des 2 Infinis Irène Joliot-Curie (IJCLab), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Tel Aviv University (TAU), Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), University of Warwick [Coventry], Department of Physics [Durham University], Durham University, University of Ljubljana, University of Basel (Unibas), Yonsei University, University College of London [London] (UCL), Syracuse University, Centre de Physique Théorique - UMR 7332 (CPT), Aix Marseille Université (AMU)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS), CPT - E1 Physique des particules, Aix Marseille Université (AMU)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS)-Aix Marseille Université (AMU)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS), Rheinisch-Westfälische Technische Hochschule Aachen University (RWTH), Universidade de Lisboa, GSI Helmholtzzentrum für Schwerionenforschung (GSI), City College of New York [CUNY] (CCNY), City University of New York [New York] (CUNY), Scuola Normale Superiore di Pisa (SNS), Université Catholique de Louvain = Catholic University of Louvain (UCL), Universität Siegen [Siegen], Istituto Nazionale di Fisica Nucleare, Sezione di Cagliari (INFN, Sezione di Cagliari), Louisiana State University (LSU), University of Glasgow, Stockholms universitet, Indiana State University, INAF/OATS, Trieste, Italy, Department of Applied Physics, Ghent University, Brown University, Università degli Studi di Milano-Bicocca = University of Milano-Bicocca (UNIMIB), Johannes Gutenberg - Universität Mainz = Johannes Gutenberg University (JGU), Weizmann Institute of Science [Rehovot, Israël], University of Bologna/Università di Bologna, University of Edinburgh, Institute of Molecular Genetics of National Research Centre «Kurchatov Institute» [Moscow, Russia], Russian Academy of Sciences [Moscow] (RAS), Instituto de Fisica Corpuscular (IFIC), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC)-Universitat de València (UV), University of Alabama [Tuscaloosa] (UA), Universitat Autònoma de Barcelona (UAB), Georg-August-University = Georg-August-Universität Göttingen, Karlsruhe Institute of Technology (KIT), University of Bristol [Bristol], Max-Planck-Institut für Physik (Werner-Heisenberg-Institut) (MPI-P), Tsung-Dao Lee Institute, Shanghai Jiao Tong, SLAC National Accelerator Laboratory (SLAC), Stanford University, U.S. Department of Energy [Washington] (DOE), Leopold Franzens Universität Innsbruck - University of Innsbruck, The National Research Nuclear University MEPhI (Moscow Engineering Physics Institute) [Moscow, Russia], University of Mary Washington, Petersburg Nuclear Physics Institute, University of Oxford, Ecole Polytechnique Fédérale de Lausanne (EPFL), Technische Universität München = Technical University of Munich (TUM), University of Cincinnati (UC), University of British Columbia (UBC), University of Washington [Seattle], Istituto Nazionale di Fisica Nucleare [Pisa] (INFN), Lund University [Lund], AstroParticule et Cosmologie (APC (UMR_7164)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), University of Pisa - Università di Pisa, University of Tennessee System, Northern Illinois University, Nagoya University, Tokyo University of Science [Tokyo], Czech Academy of Sciences [Prague] (CAS), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, University of Sheffield [Sheffield], University of Melbourne, Monash University [Melbourne], University of Barcelona, California Institute of Technology (CALTECH), Department of Radiology [Radiologische Universitätsklinik Eberhard-Karls-Universität Tübingen], University of Portsmouth, Columbia University [New York], Colorado School of Mines, University of Massachusetts [Amherst] (UMass Amherst), University of Massachusetts System (UMASS), Max Planck Institute for the Physics of Complex Systems (MPI-PKS), Max-Planck-Gesellschaft, Moscow Institute of Physics and Technology [Moscow] (MIPT), Peking University [Beijing], Institute of High Energy Physics [Beijing] (IHEP), Chinese Academy of Sciences [Changchun Branch] (CAS), Particle Data Group, Institut des Hautes Etudes Scientifiques (IHES), Laboratoire de Physique Théorique et Hautes Energies (LPTHE), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Laboratoire de Physique Nucléaire et de Hautes Énergies (LPNHE (UMR_7585)), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de l'Accélérateur Linéaire (LAL), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Nucléaire et de Hautes Énergies (LPNHE), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Pierre et Marie Curie - Paris 6 (UPMC), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Département de Physique des Particules (ex SPP) (DPP), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7), CEA/DSM, Département de Physique des Particules (ex SPP) (DPhP), UCL - SST/IRMP - Institut de recherche en mathématique et physique, Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), ITA, Department of Energy (US), Japan Society for the Promotion of Science, European Commission, Ministry of Education, Culture, Sports, Science and Technology (Japan), Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Science and Technology Facilities Council (STFC), Tanabashi, M, Grp, P, Hagiwara, K, Hikasa, K, Nakamura, K, Sumino, Y, Takahashi, F, Tanaka, J, Agashe, K, Aielli, G, Amsler, C, Antonelli, M, Asner, D, Baer, H, Banerjee, S, Barnett, R, Basaglia, T, Bauer, C, Beatty, J, Belousov, V, Beringer, J, Bethke, S, Bettini, A, Bichsel, H, Biebel, O, Black, K, Blucher, E, Buchmuller, O, Burkert, V, Bychkov, M, Cahn, R, Carena, M, Ceccucci, A, Cerri, A, Chakraborty, D, Chen, M, Chivukula, R, Cowan, G, Dahl, O, D'Ambrosio, G, Damour, T, de Florian, D, de Gouvea, A, Degrand, T, de Jong, P, Dissertori, G, Dobrescu, B, D'Onofrio, M, Doser, M, Drees, M, Dreiner, H, Dwyer, D, Eerola, P, Eidelman, S, Ellis, J, Erler, J, Ezhela, V, Fetscher, W, Fields, B, Firestone, R, Foster, B, Freitas, A, Gallagher, H, Garren, L, Gerber, H, Gerbier, G, Gershon, T, Gershtein, Y, Gherghetta, T, Godizov, A, Goodman, M, Grab, C, Gritsan, A, Grojean, C, Groom, D, Grunewald, M, Gurtu, A, Gutsche, T, Haber, H, Hanhart, C, Hashimoto, S, Hayato, Y, Hayes, K, Hebecker, A, Heinemeyer, S, Heltsley, B, Hernandez-Rey, J, Hisano, J, Hocker, A, Holder, J, Holtkamp, A, Hyodo, T, Irwin, K, Johnson, K, Kado, M, Karliner, M, Katz, U, Klein, S, Klempt, E, Kowalewski, R, Krauss, F, Kreps, M, Krusche, B, Kuyanov, Y, Kwon, Y, Lahav, O, Laiho, J, Lesgourgues, J, Liddle, A, Ligeti, Z, Lin, C, Lippmann, C, Liss, T, Littenberg, L, Lugovsky, K, Lugovsky, S, Lusiani, A, Makida, Y, Maltoni, F, Mannel, T, Manohar, A, Marciano, W, Martin, A, Masoni, A, Matthews, J, Meissner, U, Milstead, D, Mitche, R, Moenig, K, Molaro, P, Moortgat, F, Moskovic, M, Murayama, H, Narain, M, Nason, P, Navas, S, Neubert, M, Nevski, P, Nir, Y, Olive, K, Griso, S, Parsons, J, Patrignani, C, Peacock, J, Pennington, M, Petcov, S, Petrov, V, Pianori, E, Piepke, A, Pomarol, A, Quadt, A, Rademacker, J, Raffelt, G, Ratcliff, B, Richardson, P, Ringwald, A, Roesler, S, Rolli, S, Romaniouk, A, Rosenberg, L, Rosner, J, Rybka, G, Ryutin, R, Sachrajda, C, Sakai, Y, Salam, G, Sarkar, S, Sauli, F, Schneider, O, Scholberg, K, Schwartz, A, Scott, D, Sharma, V, Sharpe, S, Shutt, T, Silari, M, Sjostrand, T, Skands, P, Skwarnicki, T, Smith, J, Smoot, G, Spanier, S, Spieler, H, Spiering, C, Stah, A, Stone, S, Sumiyoshi, T, Syphers, M, Terashi, K, Terning, J, Thoma, U, Thorne, R, Tiator, L, Titov, M, Tkachenko, N, Tornqvist, N, Tovey, D, Valencia, G, Van de Water, R, Varelas, N, Venanzoni, G, Verde, L, Vincter, M, Voge, P, Vogt, A, Wakely, S, Walkowiak, W, Walter, C, Wands, D, Ward, D, Wascko, M, Weiglein, G, Weinberg, D, Weinberg, E, White, M, Wiencke, L, Willocq, S, Woh, C, Womersley, J, Woody, C, Workman, R, Yao, W, Zeller, G, Zenin, O, Zhu, R, Zhu, S, Zimmermann, F, Zyla, P, Anderson, J, Fuller, L, Lugovsky, V, Schaffner, P, Tanabashi, M., Grp, Particle Data, Hagiwara, K., Hikasa, K., Nakamura, K., Sumino, Y., Takahashi, F., Tanaka, J., Agashe, K., Aielli, G., Amsler, C., Antonelli, M., Asner, D. M., Baer, H., Banerjee, Sw., Barnett, R. M., Basaglia, T., Bauer, C. W., Beatty, J. J., Belousov, V. I., Beringer, J., Bethke, S., Bettini, A., Bichsel, H., Biebel, O., Black, K. M., Blucher, E., Buchmuller, O., Burkert, V., Bychkov, M. A., Cahn, R. N., Carena, M., Ceccucci, A., Cerri, A., Chakraborty, D., Chen, M. -C., Chivukula, R. S., Cowan, G., Dahl, O., D'Ambrosio, G., Damour, T., de Florian, D., de Gouvea, A., Degrand, T., de Jong, P., Dissertori, G., Dobrescu, B. A., D'Onofrio, M., Doser, M., Drees, M., Dreiner, H. K., Dwyer, D. A., Eerola, P., Eidelman, S., Ellis, J., Erler, J., Ezhela, V. V., Fetscher, W., Fields, B. D., Firestone, R., Foster, B., Freitas, A., Gallagher, H., Garren, L., Gerber, H. -J., Gerbier, G., Gershon, T., Gershtein, Y., Gherghetta, T., Godizov, A. A., Goodman, M., Grab, C., Gritsan, A. V., Grojean, C., Groom, D. E., Grunewald, M., Gurtu, A., Gutsche, T., Haber, H. E., Hanhart, C., Hashimoto, S., Hayato, Y., Hayes, K. G., Hebecker, A., Heinemeyer, S., Heltsley, B., Hernandez-Rey, J. J., Hisano, J., Hocker, A., Holder, J., Holtkamp, A., Hyodo, T., Irwin, K. D., Johnson, K. F., Kado, M., Karliner, M., Katz, U. F., Klein, S. R., Klempt, E., Kowalewski, R. V., Krauss, F., Kreps, M., Krusche, B., Kuyanov, Yu. V., Kwon, Y., Lahav, O., Laiho, J., Lesgourgues, J., Liddle, A., Ligeti, Z., Lin, C. -J., Lippmann, C., Liss, T. M., Littenberg, L., Lugovsky, K. S., Lugovsky, S. B., Lusiani, A., Makida, Y., Maltoni, F., Mannel, T., Manohar, A. V., Marciano, W. J., Martin, A. D., Masoni, A., Matthews, J., Meissner, U. -G., Milstead, D., Mitche, R. E., Moenig, K., Molaro, P., Moortgat, F., Moskovic, M., Murayama, H., Narain, M., Nason, P., Navas, S., Neubert, M., Nevski, P., Nir, Y., Olive, K. A., Griso, S. Pagan, Parsons, J., Patrignani, C., Peacock, J. A., Pennington, M., Petcov, S. T., Petrov, V. A., Pianori, E., Piepke, A., Pomarol, A., Quadt, A., Rademacker, J., Raffelt, G., Ratcliff, B. N., Richardson, P., Ringwald, A., Roesler, S., Rolli, S., Romaniouk, A., Rosenberg, L. J., Rosner, J. L., Rybka, G., Ryutin, R. A., Sachrajda, C. T., Sakai, Y., Salam, G. P., Sarkar, S., Sauli, F., Schneider, O., Scholberg, K., Schwartz, A. J., Scott, D., Sharma, V., Sharpe, S. R., Shutt, T., Silari, M., Sjostrand, T., Skands, P., Skwarnicki, T., Smith, J. G., Smoot, G. F., Spanier, S., Spieler, H., Spiering, C., Stah, A., Stone, S. L., Sumiyoshi, T., Syphers, M. J., Terashi, K., Terning, J., Thoma, U., Thorne, R. S., Tiator, L., Titov, M., Tkachenko, N. P., Tornqvist, N. A., Tovey, D. R., Valencia, G., Van de Water, R., Varelas, N., Venanzoni, G., Verde, L., Vincter, M. G., Voge, P., Vogt, A., Wakely, S. P., Walkowiak, W., Walter, C. W., Wands, D., Ward, D. R., Wascko, M. O., Weiglein, G., Weinberg, D. H., Weinberg, E. J., White, M., Wiencke, L. R., Willocq, S., Woh, C. C., Womersley, J., Woody, C. L., Workman, R. L., Yao, W. -M., Zeller, G. P., Zenin, O. V., Zhu, R. -Y., Zhu, S. -L., Zimmermann, F., Zyla, P. A., Anderson, J., Fuller, L., Lugovsky, V. S., Schaffner, P., Robinson, D. J., Wohl, C. G., Allanach, B. C., Aschenauer, E. C., Baudis, L., Sekhar Chivukula, R., Egede, U., Gonzalez-Garcia, M. C., Huston, J., Kenzie, M., Khoze, V. A., Lellouch, L. P., Liddle, A. R., Lourenco, C., Mikhasenko, M., Miller, D. J., Mitchell, R. E., Monig, K., Pich, A., Profumo, S., Rabbertz, K., Ramani, H., Ramsey-Musolf, M., Ryskin, M., Schwiening, J., Soffer, A., Sozzi, M. S., Stahl, A., Tasevsky, M., Trabelsi, K., Urquijo, P., van de Water, R., Vogel, P., Vogelsang, W., Vorobyev, V., Yokoyama, M., Yoshida, R., Zanderighi, G., Zheng, W., and Department of Physics
Subjects: high energy, lepton, mixing [neutrino], High Energy Physics::Lattice, Cosmic microwave background, diffraction, Technicolor, Astrophysics, Omega, 01 natural sciences, Physics, Particles & Fields, higgs-boson production, Big Bang nucleosynthesis, cosmological model: parameter space, tau, dark energy, Monte Carlo, fields, pentaquark, instrumentation, Settore FIS/01, gauge boson, Anomalous magnetic dipole moment, deep-inelastic scattering, new physics, Physics, DOUBLE-BETA-DECAY, Electroweak interaction, density [dark matter], HEAVY FLAVOUR, Quarkonium, review, particle, physics, SUPERSYMMETRIC STANDARD MODEL, square-root-s, Physics, Nuclear, grand unified theory, boson: heavy, statistics, Physical Sciences, Higgs boson, axion: mass, flavor: violation, Neutrino, ELECTROWEAK SYMMETRY-BREAKING, numerical calculations: Monte Carlo, on-line, S013EPH, Quark, heavy [boson], [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], Physics, Multidisciplinary, anomalous magnetic-moment, electroweak radiative-corrections, dark matter: density, Higgs particle, meson, neutrino masses, neutrino mixing, neutrino oscillations, 114 Physical sciences, CHIRAL PERTURBATION-THEORY, neutrino mixing, Standard Model, quark, 0202 Atomic, Molecular, Nuclear, Particle And Plasma Physics, Nucleosynthesis, quantum chromodynamics, CP: violation, Dark matter, ddc:530, particle physics, Strong Interactions, 010306 general physics, sparticle, S013DF, grand unified theories, PRODUCTION, Gauge boson, Science & Technology, neutrino masses, 010308 nuclear & particles physics, C50 Other topics in experimental particle physics, Particle Data Group, Astronomy and Astrophysics, Deep inelastic scattering, to-leading-order, Automatic Keywords, heavy boson, axion, tables (particle physics), Tetraquark, proton-proton collisions, Supersymmetry, hadron, neutrino: mixing, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], cosmology, Volume (compression), HIGGS-BOSON, UB-VERTICAL-BAR, cosmological model, dark energy density, experimental methods, ddc:539.72021, Physics beyond the Standard Model, standard model, group theory, General Physics and Astronomy, tables, particle physics, high energy physics, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], Quantum chromodynamics, energy: high, E Rev 2016, [PHYS.HTHE]Physics [physics]/High Energy Physics - Theory [hep-th], Settore FIS/01 - Fisica Sperimentale, photon, Nuclear & Particles Physics, parameter space [cosmological model], dark energy: density, high [energy], M013WX, fermion-pair production, Nuclear and High Energy Physics, Particle physics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astronomy & Astrophysics, dark matter, statistical analysis, Double beta decay, 0103 physical sciences, conservation law, cold dark-matter, TAU LEPTONS, Astrophysics::Galaxy Astrophysics, tables, DEEP-INELASTIC-SCATTERING, electroweak interaction, High Energy Physics::Phenomenology, 750 GeV diphoton excess, PRODUCTION CROSS-SECTION, baryon, density [dark energy], Physics and Astronomy, gravitation, CKM matrix, [PHYS.HPHE]Physics [physics]/High Energy Physics - Phenomenology [hep-ph], High Energy Physics::Experiment, supersymmetry, Minimal Supersymmetric Standard Model
Abstract: 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., United States Department of Energy (DOE) DE-AC02-05CH11231, government of Japan (Ministry of Education, Culture, Sports, Science and Technology), Istituto Nazionale di Fisica Nucleare (INFN), Physical Society of Japan (JPS), European Laboratory for Particle Physics (CERN), United States Department of Energy (DOE)
Published: 2018

27. Photoproduction of $ \eta{^\prime}$ -mesons off the deuteron

Author: S. Lugert, D. Walther, S. Hoeffgen, D. Trnka, I. Jaegle, M. Ostrick, Eberhard Klempt, A. V. Anisovich, Matthew Lang, U. Thoma, Kanzo Nakayama, T. Szczepanek, D. Menze, V. Metag, J. Junkersfeld, Fei Huang, V. Kleber, Wolfgang Hillert, V. Crede, H. Loehner, H. van Pee, Yu. A. Beloglazov, A. V. Sarantsev, T. Mertens, D. V. Novinski, S. Kammer, J. C. S. Bacelar, R. Gregor, R. Castelijns, V. A. Nikonov, M. Kotulla, C. Funke, L. Tiator, R. Ewald, O. Bartholomy, D. Elsner, Lalit Mohan Pant, R. Varma, Friedrich Klein, H. Dutz, Ch. Wendel, B. Krusche, Ch. Schmidt, R. W. Novotny, A. Suele, V. V. Sumachev, J. G. Messchendorp, S. Shende, B. Schoch, A. Fix, H. Kalinowsky, V. Sokhoyan, I. V. Lopatin, H. Schmieden, D. E. Bayadilov, A. B. Gridnev, Mariana Nanova, R. Beck, S. Schadmand, Ankhi Roy, E. Gutz, B. Bantes, Frank Frommberger, Frank Klein, and M. Pfeiffer
Subjects: Physics, Nuclear and High Energy Physics, Photon, Proton, Meson, Nuclear Theory, Particle accelerator, law.invention, Nuclear physics, Recoil, Deuterium, law, Neutron, High Energy Physics::Experiment, Nucleon, Nuclear Experiment
Abstract: Quasi-free photoproduction of $ \eta{^\prime}$ -mesons off nucleons bound in the deuteron has been measured with the combined Crystal Barrel - TAPS detector. The experiment was done at a tagged photon beam of the ELSA electron accelerator in Bonn for incident photon energies from the production threshold up to 2.5GeV. The $ \eta{^\prime}$ -mesons have been detected in coincidence with recoil protons and recoil neutrons. The quasi-free proton data are in good agreement with the results for free protons, indicating that nuclear effects have no significant impact. The coincidence with recoil neutrons provides the first data for the $ \gamma$ n $ \rightarrow$ n $ \eta{^\prime}$ reaction. In addition, also first estimates for coherent $ \eta{^\prime}$ -production off the deuteron have been obtained. In agreement with model predictions, the total cross-section for this channel is found to be very small, at most at the level of a few nb. The data are compared to model calculations taking into account contributions from nucleon resonances and t -channel exchanges
Published: 2018

28. Photoproduction of η -mesons off nuclei for Eγ ⩽ 2.2 GeV

Author: Lalit Mohan Pant, B. Bantes, M. Pfeiffer, D. Menze, R. Ewald, S. Hoeffgen, Ankhi Roy, Ch. Wendel, V. V. Sumachev, H. Kalinowsky, Matthew Lang, A. Ehmanns, R. Varma, D. Elsner, I. Jaegle, S. Kammer, R. Castelijns, H. Dutz, S. Shende, V. Sokhoyan, S. Lugert, D. Trnka, B. Krusche, R. W. Novotny, Ph. Hoffmeister, K. Essig, J. Langheinrich, T. Szczepanek, A. Suele, O. Bartholomy, S. Schadmand, Ulrich Mosel, R. Gregor, Yu. A. Beloglazov, M. Konrad, R. W. Gothe, Eberhard Klempt, J. C. S. Bacelar, M. Kotulla, C.-H. Weinheimer, B. Schoch, C. Morales, M. Ostrick, I. Fabry, Michael Fuchs, R. Beck, E. Gutz, J. Lotz, V. Metag, V. Crede, Ch. Schmidt, Frank Klein, Friedrich Klein, V. Kleber, H. Schmieden, I. V. Lopatin, D. E. Bayadilov, A. B. Gridnev, Mariana Nanova, H. van Pee, D. V. Novinski, J. G. Messchendorp, K. Fornet-Ponse, D. Walther, C. Funke, I. Horn, A. Radkov, T. Mertens, U. Thoma, P. Muehlich, J. Junkersfeld, and H. Loehner
Subjects: Mass number, Physics, Nuclear and High Energy Physics, Meson, Nuclear Theory, Nuclear matter, Resonance (particle physics), Nuclear physics, Pion, Production (computer science), High Energy Physics::Experiment, Absorption (logic), Nucleon, Nuclear Experiment
Abstract: Photoproduction of $\eta$ mesons off $^{12}$C, $^{40}$Ca, $^{93}$Nb, and $^{nat}$Pb nuclei has been measured with a tagged photon beam with energies between 0.6 and 2.2 GeV. The experiment was performed at the Bonn ELSA accelerator with the combined setup of the Crystal Barrel and TAPS calorimeters. It aimed at the in-medium properties of the S$_{11}$(1535) nucleon resonance and the study of the absorption properties of nuclear matter for $\eta$ mesons. Careful consideration was given to contributions from $\eta\pi$ final states and secondary production mechanisms of $\eta$-mesons e.g. from inelastic $\pi N$ reactions of intermediate pions. The analysis of the mass number scaling shows that the nuclear absorption cross section $\sigma_{N\eta}$ for $\eta$ mesons is constant over a wide range of the $\eta$ momentum. The comparison of the excitation functions to data off the deuteron and to calculations in the framework of a BUU-model show no unexplained in-medium modifications of the S$_{11}$(1535)., Comment: Accepted for publication in Eur. Phys. J. A
Published: 2018

29. Measurement of the beam asymmetry Σ and the target asymmetry T in the photoproduction of ω mesons off the proton using CLAS at Jefferson Laboratory

Author: William Brooks, George Davey Smith, R. A. Schumacher, A. El Alaoui, S. Stepanyan, J. Pierce, H. Y. Lu, P. Eugenio, G. Gavalian, I. Denisenko, N. Dashyan, Taya Chetry, M. Taiuti, A. Filippi, A. Fradi, D. P. Watts, K. A. Griffioen, Friedrich Klein, V. Crede, M. Khandaker, D. G. Meekins, Brian Raue, A. D'Angelo, A. V. Sarantsev, Yordanka Ilieva, Nicholas Zachariou, E. Pasyuk, V. Mokeev, V. Batourine, R. Paremuzyan, R. De Vita, N. Markov, L. Lanza, G. Rosner, E. Golovatch, K. Hicks, W. Kim, Sergey Kuleshov, M. Ripani, R. A. Montgomery, F. Sabatié, S. Niccolai, Carlos A. Salgado, C. D. Keith, Pawel Nadel-Turonski, D. G. Jenkins, Eberhard Klempt, B. A. Clary, J. Brock, Alessandro Rizzo, R. Dupre, M. Battaglieri, J. Zhang, C. Djalali, J. A. Tan, L. El Fassi, J. W. Price, S. Anefalos Pereira, K. Livingston, C. Hanretty, C. Carlin, M. Guidal, L. Guo, M. Ungaro, Gerard Gilfoyle, A. I. Ostrovidov, A. V. Anisovich, K. Park, G. Charles, G. Niculescu, V. A. Nikonov, G. Ciullo, J. P. Ball, B. Torayev, Y. Prok, F. X. Girod, M. E. McCracken, D. S. Carman, D. G. Ireland, M. Holtrop, K. Joo, I. Bedlinskiy, V. P. Kubarovsky, D. Riser, M. Osipenko, Andreas Klein, Nikos Sparveris, X. Wei, T. Mineeva, D. Sokhan, O. Pogorelko, S. Procureur, W. Gohn, A. Kim, Z. E. Meziani, W. Phelps, Volker D. Burkert, M. Bashkanov, A. S. Biselli, B. S. Ishkhanov, L. Elouadrhiri, K. L. Giovanetti, I. Balossino, S. Strauch, Michael Dugger, D. I. Sober, E. Voutier, I. I. Strakovsky, A. Movsisyan, B. McKinnon, Dustin Keller, S. Park, A. Deur, K. Hafidi, Iu. Skorodumina, Sylvester Joosten, S. Fegan, G. Khachatryan, P. L. Cole, Z. W. Zhao, E. Phelps, N. Gevorgyan, D. Protopopescu, W. J. Briscoe, C. Munoz Camacho, M. H. Wood, A. Celentano, R. W. Gothe, M. Contalbrigo, Z. Akbar, N. K. Walford, I. J. D. MacGregor, S. Adhikari, M. Hattawy, Martin K. Mayer, Y. G. Sharabian, C. Gleason, Barry Ritchie, P. Roy, C. A. Meyer, G. V. Fedotov, E. L. Isupov, S. Boiarinov, K. P. Adhikari, H. Hakobyan, and P. Lenisa
Subjects: Physics, Particle physics, Proton, Meson, 010308 nuclear & particles physics, Partial wave analysis, media_common.quotation_subject, Nuclear Theory, Bremsstrahlung, Observable, 7. Clean energy, 01 natural sciences, Resonance (particle physics), Asymmetry, Baryon, Nuclear physics, 13. Climate action, 0103 physical sciences, High Energy Physics::Experiment, Nuclear Experiment, 010306 general physics, media_common
Abstract: The photoproduction of ω mesons off the proton has been studied in the reaction γp→pω using the CEBAF Large Acceptance Spectrometer (CLAS) and the frozen-spin target in Hall B at the Thomas Jefferson National Accelerator Facility. For the first time, the target asymmetry T has been measured in photoproduction from the decay ω→π+π-π0, using a transversely polarized target with energies ranging from just above the reaction threshold up to 2.8 GeV. Significant nonzero values are observed for these asymmetries, reaching about 30-40% in the third-resonance region. New measurements for the photon-beam asymmetry Σ are also presented, which agree well with previous CLAS results and extend the world database up to 2.1 GeV. These data and additional ω photoproduction observables from CLAS were included in a partial-wave analysis within the Bonn-Gatchina framework. Significant contributions from s-channel resonance production were found in addition to t-channel exchange processes.
Published: 2018

30. Measurement of the helicity asymmetry E in ω→π+π−π0 photoproduction

Author: M. Contalbrigo, T. Mineeva, R. A. Schumacher, Z. Akbar, M. Khachatryan, V. Mokeev, Taya Chetry, A. V. Anisovich, G. Ciullo, J. P. Ball, Y. Prok, D. S. Carman, E. Golovatch, F. Cao, P. Roy, M. Guidal, B. S. Ishkhanov, K. Hicks, C. Gleason, Iu. Skorodumina, Nikos Sparveris, X. Wei, M. Holtrop, O. Cortes, K. P. Adhikari, C. D. Keith, E. L. Isupov, M. Ripani, Barry Ritchie, E. Voutier, Nicholas Zachariou, S. Stepanyan, Laura Clark, L. Guo, H. Egiyan, S. Boiarinov, G. Khachatryan, A. Movsisyan, I. J. D. MacGregor, E. De Sanctis, G. Charles, J. Brock, Sylvester Joosten, M. Hattawy, Carlos A. Salgado, A. Celentano, R. W. Gothe, A. V. Sarantsev, S. Park, M. Osipenko, F. Sabatié, W. J. Briscoe, I. I. Strakovsky, Y. G. Sharabian, S. Niccolai, M. Ungaro, D. I. Sober, A. I. Ostrovidov, K. Park, Michael Paolone, R. Dupre, M. Battaglieri, C. Munoz Camacho, A. Filippi, G. V. Fedotov, A. Deur, K. A. Griffioen, V. Crede, D. G. Ireland, W. Phelps, Lorenzo Zana, S. Adhikari, N. Dashyan, D. Protopopescu, Alessandro Rizzo, M. Garçon, Volker D. Burkert, B. McKinnon, W. K. Brooks, D. G. Jenkins, I. Bedlinskiy, V. A. Nikonov, Brian Raue, P. Nadel-Turonski, A. Fradi, F. X. Girod, W. Kim, I. Denisenko, V. Batourine, Michael Dugger, G. Rosner, N. Markov, R. Paremuzyan, S. Strauch, Andreas Klein, K. Livingston, W. Gohn, R. De Vita, C. Carlin, Nicholas M. Harrison, S. Anefalos Pereira, L. Lanza, D. Sokhan, A. Kim, C. Djalali, C. Hanretty, R. Fersch, H. Avakian, Eberhard Klempt, J. Zhang, H. Voskanyan, E. Pasyuk, J. W. Price, George Davey Smith, V. P. Kubarovsky, D. G. Meekins, A. D'Angelo, O. Pogorelko, Frank Klein, Dustin Keller, L. El Fassi, Michael Wood, K. Hafidi, P. L. Cole, Z. W. Zhao, P. Eugenio, M. Taiuti, N. Gevorgyan, D. Heddle, G. Hollis, Hrachya Hakobyan, M. J. Amaryan, K. L. Giovanetti, and M. Khandaker
Subjects: Physics, Meson, 010308 nuclear & particles physics, Partial wave analysis, Bremsstrahlung, Resonance, Observable, 01 natural sciences, Helicity, Nuclear physics, Pomeron, 0103 physical sciences, Nuclear Experiment, 010306 general physics, Nucleon
Abstract: The double-polarization observable E was studied for the reaction γp → pω using the CEBAF Large Acceptance Spectrometer (CLAS) in Hall B at the Thomas Jefferson National Accelerator Facility and the longitudinally polarized frozen-spin target (FROST). The observable was measured from the charged decay mode of the meson, ω → π+π−π0, using a circularly polarized tagged-photon beam with energies ranging from the ω threshold at 1.1 to 2.3 GeV. A partial-wave analysis within the Bonn-Gatchina framework found dominant contributions from the 3/2+ partial wave near threshold, which is identified with the subthreshold N(1720) 3/2+ nucleon resonance. To describe the entire data set, which consisted of ω differential cross sections and a large variety of polarization observables, further contributions from other nucleon resonances were found to be necessary. With respect to nonresonant mechanisms, π exchange in the t channel was found to remain small across the analyzed energy range, while Pomeron t-channel exchange gradually grew from the reaction threshold to dominate all other contributions above W ≈ 2 GeV.
Published: 2017

31. Measurement of the differential and total cross sections of the γd→K0Λ(p) reaction within the resonance region

Author: H. Hakobyan, M. Taiuti, Dustin Keller, N. Compton, N. Dashyan, D. I. Glazier, R. De Vita, Michael Wood, K. Hafidi, Laura Clark, Yordanka Ilieva, X. Wei, C. E. Hyde, A. Simonyan, M. Osipenko, L. Guo, Alessandro Rizzo, S. Anefalos Pereira, K. Hicks, R. Paremuzyan, R. A. Schumacher, W. Phelps, V. P. Kubarovsky, V. Crede, A. El Alaoui, J. A. Fleming, O. Pogorelko, S. M. Hughes, P. Nadel-Turonski, G. Murdoch, R. A. Montgomery, Michael Paolone, G. Gavalian, N. K. Walford, M. Camp, G. Charles, V. Mokeev, C. Gleason, Nicholas Zachariou, E. De Sanctis, K. P. Adhikari, Nicholas M. Harrison, T. Cao, H. Avakian, H. S. Jo, F. X. Girod, N. Markov, I. J. D. MacGregor, D. Heddle, C. Hanretty, Barry Ritchie, H. Voskanyan, S. Pisano, P. Lenisa, M. Contalbrigo, Avraham Klein, D. Sokhan, F. Sabatié, H. Y. Lu, G. Rosner, M. Khachatryan, I. Stankovic, Philip L. Cole, Z. Akbar, S. Adhikari, B. McKinnon, Nikolaos Sparveris, I. Bedlinskiy, E. Munevar, W. Kim, P. L. Cole, K. Livingston, Y. Ghandilyan, I. Niculescu, Friedrich Klein, D. G. Jenkins, G. Niculescu, B. S. Ishkhanov, A. D'Angelo, Taya Chetry, R. W. Gothe, Eberhard Klempt, M. Mirazita, L. El Fassi, V. Batourine, J. Zhang, S. Stepanyan, G. Khachatryan, Brian Raue, J. W. Price, Latifa Elouadrhiri, C. A. Meyer, Sergey Kuleshov, M. Ripani, M. Ungaro, A. I. Ostrovidov, K. Park, G. V. Fedotov, F. Cao, D. G. Ireland, V. A. Nikonov, Volker D. Burkert, A. S. Biselli, W. J. Briscoe, K. Joo, C. Munoz Camacho, I. I. Strakovsky, M. Guidal, Y. G. Sharabian, G. Ciullo, Y. Prok, T. Mineeva, D. S. Carman, D. Protopopescu, A. Deur, E. Voutier, S. Niccolai, A. Movsisyan, Iu. Skorodumina, W. K. Brooks, G. D. Smith, M. Holtrop, C. E. Taylor, E. Golovatch, R. Dupre, S. Strauch, D. P. Watts, H. Egiyan, A. V. Sarantsev, M. Battaglieri, B. Torayev, K. L. Giovanetti, A. Filippi, M. Khandaker, O. Cortes, E. L. Isupov, A. Fradi, Sylvester Joosten, L. Lanza, Eugene Pasyuk, Andrea Celentano, C. Djalali, N. A. Baltzell, C. Salgado, K. A. Griffioen, A. Trivedi, and P. Eugenio
Subjects: Physics, Particle physics, 010308 nuclear & particles physics, Partial wave analysis, Quark model, Gamma ray, Bremsstrahlung, Resonance, Lambda, 01 natural sciences, Particle identification, Nuclear physics, 0103 physical sciences, High Energy Physics::Experiment, Nuclear Experiment, 010306 general physics, Nucleon
Abstract: We report the first measurement of differential and total cross sections for the $\ensuremath{\gamma}d\ensuremath{\rightarrow}{K}^{0}\mathrm{\ensuremath{\Lambda}}(p)$ reaction, using data from the CLAS detector at the Thomas Jefferson National Accelerator Facility. Data collected during two separate experimental runs were studied with photon-energy coverage 0.8--3.6 GeV and 0.5-- 2.6 GeV, respectively. The two measurements are consistent giving confidence in the method and determination of systematic uncertainties. The cross sections are compared with predictions from the KAON-MAID theoretical model (without kaon exchange), which deviate from the data at higher $W$ and at forward kaon angles. These data, along with previously published cross sections for ${K}^{+}\mathrm{\ensuremath{\Lambda}}$ photoproduction, provide essential constraints on the nucleon resonance spectrum. A first partial wave analysis was performed that describes the data without the introduction of new resonances.
Published: 2017

32. N* resonances from K $\Lambda$ Λ amplitudes in sliced bins in energy

Author: D. G. Ireland, Volker D. Burkert, Eberhard Klempt, J. Stahov, R. Omerović, V. A. Nikonov, Alfred Švarc, M. Hadžimehmedović, U. Thoma, A. V. Sarantsev, and A. V. Anisovich
Subjects: Physics, Nuclear and High Energy Physics, 010308 nuclear & particles physics, Hadron, Quantum number, 7. Clean energy, 01 natural sciences, Riemann hypothesis, symbols.namesake, Amplitude, 0103 physical sciences, symbols, Invariant mass, Nuclear Experiment, 010306 general physics, Nucleon, Multipole expansion, Energy (signal processing), Mathematical physics
Abstract: The two reactions $\gamma p\to K^+\Lambda$ and $\pi^-p\to K^0\Lambda$ are analyzed to determine the leading photoproduction multipoles and the pion-induced partial wave amplitudes in slices of the invariant mass. The multipoles and the partial-wave amplitudes are simultaneously fitted in a multichannel Laurent+Pietarinen model (L+P model), which determines the poles in the complex energy plane on the second Riemann sheet close to the physical axes. The results from the L+P fit are compared with the results of an energy-dependent fit based on the Bonn-Gatchina (BnGa) approach. The study confirms the existence of several poles due to nucleon resonances in the region at about 1.9\,GeV with quantum numbers $J^P = 1/2^+$, $3/2^+, 1/2^-, 3/2^-, 5/2^-$., Comment: 18 pages, 12 figures
Published: 2017

33. The polarization observables T , P , and H and their impact onγp→pπ0multipoles

Author: Ph. Thämer, Reinhard Beck, M. Grüner, V. Hannen, Matthew Lang, J. Herick, B. Roth, Ch. Honisch, Ch. Schmidt, K. Makonyi, K.-Th. Brinkmann, S. Reeve, H. van Pee, Eberhard Klempt, D. V. Novinski, Yu. A. Beloglazov, D. Elsner, M. Becker, Ch. Wendel, V. Crede, A. V. Sarantsev, S. Friedrich, W. Meyer, V. Metag, F. Kalischewski, Francesco Messi, R. W. Novotny, B. Krusche, Ph. Hoffmeister, St. Goertz, Lilian Witthauer, A. Käser, V. A. Nikonov, D. Piontek, I. V. Lopatin, A. V. Anisovich, J. Hannappel, P. Klassen, T. C. Jude, M. Urban, M. Dieterle, Ulrich Wiedner, V. Sokhoyan, A. Thiel, U. Thoma, Ch. Funke, Wolfgang Hillert, M. Bichow, H. Schmieden, D. E. Bayadilov, A. B. Gridnev, Mariana Nanova, K. Fornet-Ponse, S. Böse, Ch. Hammann, H. Kalinowsky, D. Walther, A. Winnebeck, A. Wilson, T. Seifen, Frank Frommberger, M. Kube, K. Koop, G. Reicherz, Friedrich Klein, R. Schmitz, O. Jahn, J. Müller, Ch. Rosenbaum, H. Dutz, H. Eberhardt, E. Gutz, I. Keshelashvili, St. Runkel, A. Berlin, T. Rostomyan, D. Kaiser, M. Gottschall, and Jens Hartmann
Subjects: Physics, Nuclear and High Energy Physics, Particle physics, Photon, Linear polarization, media_common.quotation_subject, Partial wave analysis, Electron, Polarization (waves), Asymmetry, Nuclear physics, Nuclear Experiment, Nucleon, Multipole expansion, media_common
Abstract: Data on the polarization observables T, P, and H for the reaction gamma p -> p pi(0) are reported. Compared to earlier data from other experiments, our data are more precise and extend the covered range in energy and angle substantially. The results were extracted from azimuthal asymmetries measured using a transversely polarized target and linearly polarized photons. The data were taken at the Bonn electron stretcher accelerator ELSA with the CBELSA/TAPS detector. Within the Bonn-Gatchina partial wave analysis, the new polarization data lead to a significant narrowing of the error band for the multipoles for neutral-pion photoproduction. (C) 2015 The Authors. Published by Elsevier B.V.
Published: 2015

34. Data onIsandIcinγ→p→pπ0π0reveal cascade decays ofN(1900)viaN(1520)π

Author: H. Schmieden, D. E. Bayadilov, Mariana Nanova, M. Pfeiffer, Y. Beloglazov, H. Dutz, A. Suele, D. Walther, E. Gutz, D. Piontek, V. Crede, T. Szczepanek, J. C. S. Bacelar, A. V. Sarantsev, I. V. Lopatin, Matthew Lang, Frank Frommberger, Lalit Mohan Pant, M. Fuchs, V. Kleber, R. Gregor, Friedrich Klein, A. Gridnev, V. Metag, M. Kotulla, V. Sokhoyan, A. V. Anisovich, Ch. Schmidt, U. Thoma, A. Thiel, R. Ewald, M. Ostrick, S. Kammer, S. Lugert, J. G. Messchendorp, J. Junkersfeld, T. Mertens, Herbert Löhner, Eberhard Klempt, Ch. Funke, I. Jaegle, D. Trnka, R. Varma, B. Bantes, V. A. Nikonov, I. Horn, R. Beck, R. Castelijns, D. V. Novinski, B. Krusche, H. Kalinowsky, Ankhi Roy, Ch. Wendel, V. V. Sumachev, Wolfgang Hillert, D. Elsner, R. W. Novotny, Ph. Hoffmeister, O. Bartholomy, H. van Pee, S. Shende, Frank Klein, and A. Wilson
Subjects: Baryon, Physics, Nuclear physics, Nuclear and High Energy Physics, Pion, Photon, Linear polarization, Partial wave analysis, Photon polarization, Pi, Dalitz plot
Abstract: Photoproduction of two neutral pions off the proton is studied using linearly polarized photons, and the polarization observables I-s and I-c are measured for the first time. These two observables are unique to multi-meson final states; they characterize correlations between the linear photon polarization and the direction of outgoing single particles in photoproduction of three-body final states. The I-s and I-c distributions suggest that, in the 1.8 to 2.0 GeV mass region, the N(1520) 3/2(-)pi intermediate state is reached with reaction dynamics consistent with a dominant J(P) = 3/2(+) wave. These data are included in the Bonn-Gatchina (BnGa) partial wave analysis which is based on a large variety of data; the analysis confirms a significant contribution from the reaction chain gamma p -> N(1900)3/2(+) -> N(1520)3/2(-)pi(0) -> p pi(0)pi(0). (C) 2015 The Authors. Published by Elsevier B.V.
Published: 2015

35. Measurement of polarisation observables inKs0Σ+photoproduction off the proton

Author: Volker Metag, H. Dutz, S. Schadmand, T. Mertens, T. C. Jude, Matthew Lang, H. Schmieden, R. Ewald, D. E. Bayadilov, K. Fornet-Ponse, A. B. Gridnev, Mariana Nanova, D. Walther, A. Suele, V. Sokhoyan, Friedrich Klein, J. G. Messchendorp, V. Kleber, T. Szczepanek, M. Ostrick, Herbert Löhner, A. Roy, I. Jaegle, K.-T. Brinkmann, I. V. Lopatin, Ch. Schmidt, R. Varma, V. Crede, E. Gutz, D. Trnka, O. Jahn, R. Beck, Wolfgang Hillert, Lalit Mohan Pant, B. Bantes, S. Kammer, Ch. Funke, D. Elsner, Yu. A. Beloglazov, A. V. Sarantsev, V. A. Nikonov, R. W. Novotny, A. V. Anisovich, Ph. Hoffmeister, B. Schoch, D. Menze, Eberhard Klempt, J. Hannappel, Ch. Wendel, V. V. Sumachev, U. Thoma, J. Junkersfeld, S. Shende, H. Kalinowsky, D. V. Novinski, H. van Pee, B. Krusche, O. Bartholomy, Frank Klein, and Frank Frommberger
Subjects: Physics, Nuclear physics, Nuclear and High Energy Physics, Photon, Proton, Partial wave analysis, Hyperon, Bremsstrahlung, Photon energy, Nuclear Experiment, Nucleon, 7. Clean energy, Sigma baryon
Abstract: The reaction γ p → K S 0 Σ + is studied in the photon energy range from threshold. Linearly polarised photon beams from coherent bremsstrahlung enabled the first measurement of photon beam asymmetries in this reaction up to E γ = 1650 MeV . In addition, the recoil hyperon polarisation was determined through the asymmetry in the weak decay Σ + → p π 0 up to E γ = 2250 MeV . The data are compared to partial wave analyses, and the possible impact on the interpretation of a recently observed prominent structure in the cross section near the K ⁎ thresholds is discussed.
Published: 2014

36. Differential cross sections and polarization observables from CLAS K* photoproduction and the search for new N* states

Author: G. Khachatryan, W. J. Briscoe, R. A. Schumacher, G. Rosner, Y. Ghandilyan, Andrew Puckett, P. Lenisa, C. Hanretty, N. K. Walford, Michael Dugger, C. A. Meyer, Nikolaos Sparveris, I. J. D. MacGregor, R. A. Badui, C. Djalali, V. Crede, R. W. Gothe, A. I. Ostrovidov, K. Park, W. Phelps, M. J. Amaryan, F. Sabatié, L. El Fassi, G. V. Fedotov, D. A. Jenkins, Friedrich Klein, M. Battaglieri, Brian Raue, E. Fanchini, R. A. Montgomery, P. Peng, I. Zonta, Hovanes Egiyan, C. Munoz Camacho, D. G. Ireland, Eberhard Klempt, L. A. Net, E. De Sanctis, J. W. Price, L. Clark, H. Jiang, Z. Akbar, K. L. Giovanetti, I. Bedlinskiy, A. Deur, R. Paremuzyan, H. S. Jo, F. X. Girod, N. Compton, Volker D. Burkert, A. S. Biselli, Nicholas M. Harrison, Y. G. Sharabian, M. Ripani, D. Sokhan, L. Guo, B. McKinnon, A. Ni, A. Filippi, M. Contalbrigo, I. Stankovic, P. Nadel-Turonski, Michael Paolone, E. Munevar, M. Ungaro, B. S. Ishkhanov, M. Mirazita, M. Khandaker, R. Dupre, I. Niculescu, W. Tang, Sylvester Joosten, K. A. Griffioen, V. Batourine, P. L. Cole, R. De Vita, M. Osipenko, E. L. Isupov, Iu. Skorodumina, V. A. Nikonov, Ye Tian, J. A. Fleming, W. Kim, S. Anefalos Pereira, A. D'Angelo, L. Lanza, V. Sytnik, K. Hicks, P. Eugenio, N. Markov, S. Pisano, Victor Mokeev, G. Murdoch, Andrea Celentano, P. Roy, D. Adikaram, N. Gevorgyan, C. Gleason, Barry Ritchie, J. Ball, M. Hattawy, G. D. Smith, M. Holtrop, Taya Chetry, N. Dashyan, K. Livingston, Jie Zhang, S. Stepanyan, A. El Alaoui, Y. Ilieva, Nicholas Zachariou, E. Voutier, V. P. Kubarovsky, O. Pogorelko, S. M. Hughes, Dustin Keller, Michael Wood, H. Voskanyan, E. Pasyuk, G. Ciullo, Y. Prok, D. S. Carman, S. Strauch, D. P. Watts, S. Niccolai, A. Movsisyan, A. V. Sarantsev, S. Chandavar, A. V. Anisovich, Département de Physique Nucléaire (ex SPhN) (DPHN), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Université Paris-Sud - Paris 11 (UP11), Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), CLAS, Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), and Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])
Subjects: Polarization observables, Photon, experimental methods, magnetic field, 01 natural sciences, B004:Desig=16, Settore FIS/04 - Fisica Nucleare e Subnucleare, Recoil, electron: recoil, B016.178, N(2100), B144:Desig=19, B071:Desig=179, electron: beam, photon: tagged beam, spin: density matrix, B132:Desig=13, Nuclear Experiment, B087.14, Physics, B005.22, B144.19, Bremsstrahlung, Lambda: polarization, B004.16, Polarization (waves), Breit-Wigner, B005:Desig=22, lcsh:QC1-999, Meson photoproduction, resonance, differential cross section, Baryon spectroscopy, branching ratio, missing-mass, Jefferson Lab, B016:Desig=178, Nuclear and High Energy Physics, Particle physics, B006.21, Partial wave analysis, B006:Desig=21, Socio-culturale, Photon energy, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], polarization: recoil, bremsstrahlung, Nuclear physics, CLAS, 0103 physical sciences, B024.15, 010306 general physics, 010308 nuclear & particles physics, Branching fraction, Resonance, B132.13, partial wave analysis, B087:Desig=14, meson: photoproduction, B024:Desig=15, 4.02 GeV, baryon: hadron spectroscopy, High Energy Physics::Experiment, B071.179, lcsh:Physics, dipole, experimental results
Abstract: The reaction γp→K⁎+Λ was measured using the CLAS detector for photon energies between the threshold and 3.9 GeV at the Thomas Jefferson National Accelerator Facility. For the first time, spin-density matrix elements have been extracted for this reaction. Differential cross sections, spin density matrix elements, and the Λ recoil polarization are compared with theoretical predictions using the BnGa partial wave analysis. The main result is the evidence for significant contributions from N(1895)1/2− and N(2100)1/2+ to the reaction. Branching ratios for decays into K⁎Λ for these resonances and further resonances are reported.
Published: 2017

37. N ⁎ → Nη ′ decays from photoproduction of η ′ -mesons off protons

Author: V. A. Nikonov, Barry Ritchie, Eberhard Klempt, Michael Dugger, A. V. Anisovich, P. Collins, U. Thoma, A. V. Sarantsev, and Volker D. Burkert
Subjects: Physics, Nuclear and High Energy Physics, Particle physics, Polarization observables, Particle properties, Meson, 010308 nuclear & particles physics, Branching fraction, media_common.quotation_subject, Partial wave analysis, Baryon spectroscopy, Resonance, 01 natural sciences, Asymmetry, Helicity, Meson photoproduction, lcsh:QC1-999, Nuclear physics, 0103 physical sciences, 010306 general physics, lcsh:Physics, media_common
Abstract: A study of the partial-wave content of the γ p → η ′ p reaction in the fourth resonance region is presented, which has been prompted by new measurements of polarization observables for that process. Using the Bonn–Gatchina partial-wave formalism, the incorporation of new data indicates that the N ( 1895 ) 1 / 2 − , N ( 1900 ) 3 / 2 + , N ( 2100 ) 1 / 2 + , and N ( 2120 ) 3 / 2 − are the most significant contributors to the photoproduction process. New results for the branching ratios of the decays of these more prominent resonances to N η ′ final states are provided; such branches have not been indicated in the most recent edition of the Review of Particle Properties. Based on the analysis performed here, predictions for the helicity asymmetry E for the γ p → η ′ p reaction are presented.
Published: 2017

38. Beam-Target Helicity Asymmetry for γ→n→→π−p in the N* Resonance Region

Author: C. Gleason, Barry Ritchie, G. V. Fedotov, K. P. Adhikari, J. Ball, M. Hattawy, D. P. Watts, Marco Ripani, H. Hakobyan, G. Rosner, S. Fegan, F. X. Girod, M. Ungaro, K. A. Griffioen, I. I. Strakovsky, K. Livingston, R. Paremuzyan, C. Djalali, X. Wei, A. V. Sarantsev, A. Deur, L. Elouadrhiri, Y. Ghandilyan, R. A. Schumacher, Nicholas M. Harrison, Gerard Gilfoyle, Z. Akbar, V. Crede, L. Lanza, D. I. Glazier, M. Osipenko, Jie Zhang, E. Pasyuk, G. Khachatryan, R. A. Montgomery, P. Lenisa, P. L. Cole, G. Ciullo, D. Sokhan, N. Markov, D. S. Carman, W. Phelps, V. P. Kubarovsky, D. Riser, P. Eugenio, L. Clark, M. Bashkanov, V. Laine, O. Pogorelko, W. J. Briscoe, F. J. Klein, S. Niccolai, R. Fersch, S. M. Hughes, B. McKinnon, Nikolaos Sparveris, A. Movsisyan, M. M. Lowry, I. Zonta, R. De Vita, N. Dashyan, H. S. Jo, C. Salgado, Avraham Klein, Ron L. Workman, F. Sabatié, I. Bedlinskiy, L. Colaneri, Andrea Celentano, C. Bass, Dustin Keller, H. Y. Lu, Yordanka Ilieva, E. Golovatch, S. Strauch, N. K. Walford, R. Dupre, G. Charles, Alfred Švarc, S. Procureur, L. El Fassi, Victor Mokeev, Z. W. Zhao, J. A. Fleming, J. W. Price, D. Ho, Michael Wood, T. Kageya, A. M. Sandorfi, Y. G. Sharabian, Taya Chetry, S. Anefalos Pereira, I. J. D. MacGregor, W. Kim, P. Collins, G. Niculescu, V. A. Nikonov, A. D'Angelo, R. W. Gothe, C. S. Whisnant, E. L. Isupov, M. Battaglieri, Ye Tian, H. Voskanyan, A. Fradi, K. Joo, K. Hicks, E. De Sanctis, V. Batourine, D. A. Jenkins, Sergey Kuleshov, D. G. Ireland, H. Jiang, C. S. Nepali, P. Peng, K. Park, D. I. Sober, Volker D. Burkert, C. Munoz Camacho, A. S. Biselli, Tim O'Connell, Eberhard Klempt, B. S. Ishkhanov, D. Adikaram, T. Mineeva, M. Guidal, L. Guo, Alessandro Rizzo, S. Joosten, G. D. Smith, M. Holtrop, D. Protopopescu, C. Hanretty, A. Kim, W. Gohn, E. Voutier, A. El Alaoui, Nicholas Zachariou, B. Torayev, M. J. Amaryan, H. Avakian, M. Contalbrigo, M. Khandaker, A. Filippi, M. Paolone, Iu. Skorodumina, and G. Murdoch
Subjects: Physics, Photon, 010308 nuclear & particles physics, General Physics and Astronomy, 7. Clean energy, 01 natural sciences, Helicity, Nuclear physics, Deuterium, Solid hydrogen, Isospin, 0103 physical sciences, Neutron, Invariant mass, Nuclear Experiment, 010306 general physics, Nucleon
Abstract: We report the first beam-target double-polarization asymmetries in the γ þ nðpÞ → π− þ pðpÞ reaction spanning the nucleon resonance region from invariant mass W ¼ 1500 to 2300 MeV. Circularly polarized photons and longitudinally polarized deuterons in solid hydrogen deuteride (HD) have been used with the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab. The exclusive final state has been extracted using three very different analyses that show excellent agreement, and these have been used to deduce the E polarization observable for an effective neutron target. These results have been incorporated into new partial wave analyses and have led to significant revisions for several γnN* resonance photocouplings.
Published: 2017

39. Photon beam asymmetry Σ for η and η′ photoproduction from the proton

Author: K. A. Griffioen, I. I. Strakovsky, S. Strauch, H. Egiyan, Michael Dugger, Sylvester Joosten, Latifa Elouadrhiri, C. A. Meyer, Michael Paolone, P. Eugenio, M. Taiuti, A. Deur, K. Livingston, G. V. Fedotov, R. A. Schumacher, N. Markov, W. Phelps, W. K. Brooks, M. Osipenko, S. Pisano, F. X. Girod, E. Golovatch, R. Dupre, M. Ungaro, A. V. Sarantsev, X. Wei, G. Murdoch, M. Ripani, V. Crede, P. Collins, Iu. Skorodumina, M. Khachatryan, P. Nadel-Turonski, F. Sabatié, L. Lanza, C. Gleason, Michael Döring, D. Heddle, K. P. Adhikari, D. Sadasivan, R. Paremuzyan, N. K. Walford, A. Kim, J. W. Price, V. A. Nikonov, A. I. Ostrovidov, K. Park, Taya Chetry, S. Stepanyan, D. I. Glazier, G. Khachatryan, Barry Ritchie, G. Charles, R. A. Montgomery, Avraham Klein, C. Djalali, A. El Alaoui, Y. Ilieva, J. Ball, W. Kim, D. G. Ireland, G. Niculescu, V. P. Kubarovsky, R. De Vita, Volker D. Burkert, Nicholas Zachariou, H. S. Jo, S. Chandavar, A. V. Anisovich, A. S. Biselli, I. Bedlinskiy, I. J. D. MacGregor, M. Battaglieri, W. J. Briscoe, N. Compton, O. Pogorelko, S. M. Hughes, Nicholas M. Harrison, Gerard Gilfoyle, K. Hicks, B. Torayev, D. G. Jenkins, E. Fanchini, Y. G. Sharabian, H. Avakian, M. J. Amaryan, S. Anefalos Pereira, I. Niculescu, P. Lenisa, D. Sokhan, L. Guo, H. Hakobyan, O. Cortes, E. L. Isupov, Alessandro Rizzo, Laura Clark, H. Voskanyan, Eberhard Klempt, V. Mokeev, Ye Tian, D. Protopopescu, E. De Sanctis, M. Bashkanov, M. Contalbrigo, P. L. Cole, J. A. Fleming, E. Pasyuk, E. Voutier, C. Hanretty, J. Zhang, B. McKinnon, G. Ciullo, Friedrich Klein, Brian Raue, F. Cao, P. Roy, Y. Prok, D. S. Carman, K. L. Giovanetti, Nikos Sparveris, I. Balossino, G. Rosner, D. Rönchen, Dustin Keller, M. Mirazita, S. Niccolai, A. Movsisyan, B. S. Ishkhanov, C. Salgado, N. Dashyan, A. D'Angelo, A. Filippi, Z. Akbar, Y. Ghandilyan, K. Hafidi, M. Khandaker, G. D. Smith, M. Holtrop, A. Celentano, R. W. Gothe, L. El Fassi, C. Munoz Camacho, and L. Colaneri
Subjects: Nuclear and High Energy Physics, Photon, Proton, Meson, Meson photoproduction, Eta photoproduction, Eta-prime photoproduction, Polarization observable, Photon beam asymmetry, Nuclear Theory, Photon energy, 01 natural sciences, Particle identification, Settore FIS/04 - Fisica Nucleare e Subnucleare, Nuclear physics, 0103 physical sciences, Nuclear Experiment, 010306 general physics, Physics, 010308 nuclear & particles physics, Bremsstrahlung, Particle Data Group, lcsh:QC1-999, High Energy Physics::Experiment, Atomic physics, Nucleon, lcsh:Physics
Abstract: Measurements of the linearly-polarized photon beam asymmetry Σ for photoproduction from the proton of η and η′ mesons are reported. A linearly-polarized tagged photon beam produced by coherent bremsstrahlung was incident on a cryogenic hydrogen target within the CEBAF Large Acceptance Spectrometer. Results are presented for the γp→ηp reaction for incident photon energies from 1.070 to 1.876 GeV, and from 1.516 to 1.836 GeV for the γp→η′p reaction. For γp→ηp, the data reported here considerably extend the range of measurements to higher energies, and are consistent with the few previously published measurements for this observable near threshold. For γp→η′p, the results obtained are consistent with the few previously published measurements for this observable near threshold, but also greatly expand the incident photon energy coverage for that reaction. Initial analysis of the data reported here with the Bonn–Gatchina model strengthens the evidence for four nucleon resonances – the N(1895)1/2−, N(1900)3/2+, N(2100)1/2+ and N(2120)3/2− resonances – which presently lack the “four-star” status in the current Particle Data Group compilation, providing examples of how these new measurements help refine models of the photoproduction process.
Published: 2017

40. Scrutinizing the evidence for N(1685)

Author: Volker D. Burkert, U. Thoma, A. V. Anisovich, A. V. Sarantsev, V. A. Nikonov, and Eberhard Klempt
Subjects: Physics, Particle physics, 010308 nuclear & particles physics, 0103 physical sciences, Parity (physics), Observable, Nuclear Experiment, 010306 general physics, 01 natural sciences
Abstract: The helicity-dependent observable $E$ for the reaction $\ensuremath{\gamma}d\ensuremath{\rightarrow}\ensuremath{\eta}n(p)$ with a spectator proton was recently measured by the A2 Collaboration at MAMI in Mainz. The data were interpreted as further evidence for a narrow resonance with spin and parity ${J}^{P}=1/{2}^{+}$ $({P}_{11}$ wave). However, a full partial-wave analysis without any narrow resonance leads to an excellent description of the data. Imposing a narrow resonance with the properties suggested by the A2 Collaboration leads to a significant deterioration of the fit quality: there is no need for a narrow resonance.
Published: 2017

41. Study of the narrow structure at 1685 MeV in γp→ηp

Author: V. A. Nikonov, Maxim V. Polyakov, A. V. Sarantsev, U. Thoma, V. Kuznetsov, A. V. Anisovich, and Eberhard Klempt
Subjects: Coupling, Physics, Nuclear and High Energy Physics, media_common.quotation_subject, Resonance, Observable, Asymmetry, Nuclear physics, Cross section (physics), Amplitude, Isobar, Atomic physics, Beam (structure), media_common
Abstract: Results of a coupled channel isobar analysis of new high-statistics data on γ p → p η from MAMI are presented. A fit using known broad resonances and only standard background amplitudes cannot describe the relatively narrow peaking structure in the cross section in the mass region of 1660–1750 MeV which follows a minimum. An improved description of the data can be reached by either assuming the existence of a narrow resonance at a mass of about 1700 MeV with small photo-coupling or by a threshold effect. In the latter case the observed structure is explained by a strong (resonant or non-resonant) γ p → ω p coupling in the S 11 partial wave. When the beam asymmetry data, published by part of the GRAAL Collaboration, are included in the fit, the solution with a narrow P 11 state is slightly preferred. In that fit, mass and width of the hypothetical resonance are determined to M ∼ 1694 MeV and Γ ∼ 40 MeV , respectively, and the photo-coupling to Br η N A 1 / 2 p ∼ 2.6 ⋅ 10 − 3 GeV − 1 / 2 . High-precision measurements of the target asymmetry and F -observable are mandatory to establish the possible existence of such a narrow state and to provide the necessary information to define which partial wave is responsible for the structure observed in the data.
Published: 2013

42. Determination of the eta '-nucleus optical potential

Author: Ch. Hammann, Friedemann Zenke, Ch. Honisch, Ch. Schmidt, R. Ewald, P. Drexler, A. Winnebeck, Yasser Maghrbi, E. Ya. Paryev, J. Müller, R. Beck, H. Eberhardt, Jens Hartmann, S. Friedrich, T. Seifen, I. Keshelashvili, Friedrich Klein, D. Walther, U. Thoma, A. Thiel, T. Dahlke, H. Schmieden, Matthew Lang, D. E. Bayadilov, A. B. Gridnev, Mariana Nanova, V. Metag, V. Kleber, Ch. Wendel, I. Jaegle, Eberhard Klempt, K.-T. Brinkmann, Wolfgang Hillert, D. Kaiser, J. Hannappel, Yu. A. Beloglazov, D. Piontek, D. Elsner, I. V. Lopatin, Ph. Hoffmeister, S. Böse, B. Krusche, H. Kalinowsky, S. Kammer, F. Dietz, Th. Challand, Ch. Funke, U. Wiedner, K. Fornet-Ponse, T. Odenthal, D. Hammann, K. Makonyi, H. van Pee, Steffen Schaepe, A. Wilson, Frank Frommberger, M. Grüner, V. Crede, M. Gottschall, E. Gutz, B. Bantes, and R. Schmitz
Subjects: Physics, Excitation function, Nuclear and High Energy Physics, Photon, Meson, 010308 nuclear & particles physics, Hadron, Nuclear Theory, Elementary particle, Electron, Nuclear matter, 01 natural sciences, 0103 physical sciences, Bound state, High Energy Physics::Experiment, Atomic physics, 010306 general physics, Nuclear Experiment
Abstract: The excitation function and momentum distribution of $\eta^\prime$ mesons have been measured in photon induced reactions on $^{12}{}$C in the energy range of 1250-2600 MeV. The experiment was performed with tagged photon beams from the ELSA electron accelerator using the Crystal Barrel and TAPS detectors. The data are compared to model calculations to extract information on the sign and magnitude of the real part of the $\eta^\prime$-nucleus potential. Within the model, the comparison indicates an attractive potential of -($37 \pm 10(stat)\pm10(syst)$) MeV depth at normal nuclear matter density. Since the modulus of this depth is larger than the modulus of the imaginary part of the $\eta^\prime$-nucleus potential of -($10\pm2.5$) MeV, determined by transparency ratio measurements, a search for resolved $\eta^\prime$-bound states appears promising., Comment: 13 pages, 6 figures
Published: 2013

43. The impact of new polarization data from Bonn, Mainz and Jefferson Laboratory on $\gamma p \rightarrow \pi N$ multipoles

Author: Eberhard Klempt, A. V. Anisovich, V. L. Kashevarov, Y. Wunderlich, Jens Hartmann, A. V. Sarantsev, U. Thoma, I. I. Strakovsky, M. Ostrick, L. Tiator, Ulf-G. Meißner, R. Beck, Ron L. Workman, V. A. Nikonov, A. Thiel, M. Gottschall, D. Rönchen, and Michael Döring
Subjects: Physics, Scattering cross-section, Nuclear and High Energy Physics, Particle physics, 010308 nuclear & particles physics, media_common.quotation_subject, Hadron, Polarization (waves), 01 natural sciences, Asymmetry, Nuclear physics, 0103 physical sciences, Nuclear Experiment, 010306 general physics, Multipole expansion, Nuclear theory, media_common
Abstract: New data on pion-photoproduction off the proton have been included in the partial-wave analyses Bonn-Gatchina and SAID and in the dynamical coupled-channel approach Julich-Bonn. All reproduce the recent new data well: the double-polarization data for E, G, H, P and T in $\gamma p\rightarrow \pi^{0}p$ from ELSA, the beam asymmetry $ \Sigma$ for $\gamma p\rightarrow \pi^{0}p$ and $ \pi^{+}n$ from Jefferson Laboratory, and the precise new differential cross section and beam asymmetry data $\Sigma$ for $\gamma p\rightarrow \pi^{0}p$ from MAMI. The new fit results for the multipoles are compared with predictions not taking into account the new data. The mutual agreement is improved considerably but still far from being perfect.
Published: 2016

44. Double-polarization observable G in neutral-pion photoproduction off the proton

Author: U. Thoma, V. Crede, F. Afzal, Reinhard Beck, D. Elsner, P. Klassen, H. Dutz, K.-T. Brinkmann, S. Kammer, S. Runkel, H. Eberhardt, D. Walther, I. Keshelashvili, Ch. Honisch, Ch. Hammann, K. Fornet-Ponse, Ch. Schmidt, Ch. Funke, B. Krusche, Ch. Wendel, M. Grüner, E. Gutz, Jens Hartmann, S. Böse, A. Winnebeck, G. Reicherz, A. V. Anisovich, P. Mahlberg, H. Kalinowsky, K. Spieker, M. Bichow, Friedrich Klein, S. Friedrich, J. Müllers, Eberhard Klempt, Volker Metag, A. V. Sarantsev, Matthew Lang, W. Meyer, St. Goertz, M. Urban, Frank Frommberger, D. Kaiser, M. Dieterle, V. A. Nikonov, F. Kalischewski, B. Bantes, V. Sokhoyan, K. Koop, R. Ewald, H. Schmieden, D. E. Bayadilov, A. Thiel, A. B. Gridnev, Mariana Nanova, M. Kube, M. Gottschall, Wolfgang Hillert, J. Hannappel, Ph. Hoffmeister, V. Kleber, T. Seifen, Alastair J. Wilson, T. C. Jude, D. Piontek, I. V. Lopatin, Lilian Witthauer, D. Hammann, K. Makonyi, S. Reeve, H. van Pee, and J. Müller
Subjects: Physics, Nuclear and High Energy Physics, Photon, Proton, 010308 nuclear & particles physics, Nuclear Theory, Bremsstrahlung, Diamond, FOS: Physical sciences, Observable, Photon energy, engineering.material, Polarization (waves), 01 natural sciences, Nuclear physics, Pion, 0103 physical sciences, engineering, ddc:530, Nuclear Experiment (nucl-ex), 010306 general physics, Nuclear Experiment
Abstract: This paper reports on a measurement of the double-polarization observable G in $\pi^0$ photoproduction off the proton using the CBELSA/TAPS experiment at the ELSA accelerator in Bonn. The observable G is determined from reactions of linearly-polarized photons with longitudinally-polarized protons. The polarized photons are produced by bremsstrahlung off a properly oriented diamond radiator. A frozen spin butanol target provides the polarized protons. The data cover the photon energy range from 617 to 1325 MeV and a wide angular range. The experimental results for G are compared to predictions by the Bonn-Gatchina (BnGa), J\"ulich-Bonn (J\"uBo), MAID and SAID partial wave analyses. Implications of the new data for the pion photoproduction multipoles are discussed.
Published: 2016
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45. Anomaly in the KS0Σ+ photoproduction cross section off the proton at the K⁎ threshold

Author: Volker Metag, Wolfgang Hillert, S. Shende, A. Suele, D. Walther, S. Kammer, Ch. Funke, Frank Frommberger, J. Hannappel, H. van Pee, D. Elsner, B. Krusche, D. Menze, R. W. Novotny, Ph. Hoffmeister, O. Bartholomy, B. Schoch, H. Schmieden, U. Thoma, D. E. Bayadilov, A. B. Gridnev, E. Gutz, A. Roy, Mariana Nanova, T. Szczepanek, V. Sokhoyan, Eberhard Klempt, Yu. A. Beloglazov, Ch. Wendel, R. Beck, V. V. Sumachev, Frank Klein, J. Junkersfeld, K. T Brinkmann, H. Kalinowsky, Matthew Lang, S. Schadmand, M. Ostrick, V. Kleber, R. Varma, L. M. Pant, H. Dutz, V. Crede, T. Mertens, Herbert Löhner, R. Ewald, B. Bantes, D. V. Novinski, D. Trnka, Ch. Schmidt, O. Jahn, K. Fornet-Ponse, I. Jaegle, Friedrich Klein, I. V. Lopatin, T. C. Jude, and J. G. Messchendorp
Subjects: Physics, Nuclear physics, Baryon, Nuclear and High Energy Physics, Cross section (physics), Proton, Meson, Hadron, Elementary particle, Strangeness, Nucleon
Abstract: The γ + p → K 0 + Σ + photoproduction reaction is investigated in the energy region from threshold to E γ = 2250 MeV . The differential cross section exhibits increasing forward-peaking with energy, but only up to the K ⁎ threshold. Beyond, it suddenly returns to a flat distribution with the forward cross section dropping by a factor of four. In the total cross section a pronounced structure is observed between the K ⁎ Λ and K ⁎ Σ thresholds.
Published: 2012

46. Evidence for a negative-parity spin-doublet of nucleon resonances at 1.88 GeV

Author: Eberhard Klempt, H. Schmieden, A. V. Sarantsev, V. A. Nikonov, A. V. Anisovich, and U. Thoma
Subjects: Physics, Nuclear and High Energy Physics, Particle physics, Chiral symmetry, Degenerate energy levels, FOS: Physical sciences, Parity (physics), High Energy Physics - Experiment, Nuclear physics, High Energy Physics - Experiment (hep-ex), Pion, Nuclear Experiment (nucl-ex), Nuclear Experiment, Nucleon, Excitation
Abstract: Evidence is reported for two nucleon resonances with spin-parity $J^P=1/2^-$ and $J^P=3/2^-$ at a mass just below 1.9\,GeV. The evidence is derived from a coupled-channel analysis of a large number of pion and photo-produced reactions. The two resonances are nearly degenerate in mass with two resonances of the same spin but positive parity. Such parity doublets are predicted in models claiming restoration of chiral symmetry in high-mass excitations of the nucleon. Further examples of spin parity doublets are found in addition. Alternatively, the spin doublet can be interpreted as member of the 56-plet expected in the third excitation band of the nucleon. Implications for the problem of the {\it missing resonances} are discussed., 10 pages, 3 figures, 4 tables, minor revision
Published: 2012

47. Transparency ratio in γA→η′A′ and the in-medium η′ width

Author: B. Krusche, I. Horn, V. Metag, A. Radkov, S. Lugert, O. Bartholomy, D. Menze, Angels Ramos, Eberhard Klempt, S. Höffgen, K.-T. Brinkmann, T. Szczepanek, Ch. Wendel, I. Jaegle, A. Süle, V. V. Sumachev, J. Junkersfeld, K. Essig, C. Morales, M. Fuchs, H. Dutz, Frank Klein, Yu. A. Beloglazov, A. Ehmanns, E. Gutz, Ch. Funke, M. Konrad, Lalit Mohan Pant, M. Ostrick, H. Kalinowsky, M. Pfeiffer, Friedrich Klein, K. Makonyi, R. Ewald, I. V. Lopatin, T. Mertens, Herbert Löhner, H. van Pee, V. Crede, B. Kopf, D. Trnka, J. Langheinrich, J. G. Messchendorp, D. Elsner, U. Thoma, Ankhi Roy, R. W. Novotny, J. Lotz, D. Walther, Ph. Hoffmeister, B. Schoch, Ch. Schmidt, Eulogi Oset, H. Schmieden, D. E. Bayadilov, A. B. Gridnev, Mariana Nanova, I. Fabry, S. Schadmand, R. Gregor, and R. Varma
Subjects: Physics, Nuclear and High Energy Physics, Photon, Proton, Meson, 010308 nuclear & particles physics, Scattering, Nuclear Theory, Niobium, chemistry.chemical_element, Rest frame, 7. Clean energy, 01 natural sciences, Momentum, Nuclear physics, Cross section (physics), chemistry, 0103 physical sciences, High Energy Physics::Experiment, Atomic physics, Nuclear Experiment, 010306 general physics
Abstract: The photoproduction of η ′ -mesons off different nuclei has been measured with the CBELSA/TAPS detector system for incident photon energies between 1500–2200 MeV. The transparency ratio has been deduced and compared to theoretical calculations describing the propagation of η ′ -mesons in nuclei. The comparison indicates a width of the η ′ -meson of the order of Γ = 15 – 25 MeV at ρ = ρ 0 for an average momentum p η ′ = 1050 MeV / c , at which the η ′ -meson is produced in the nuclear rest frame. The inelastic η ′ N cross section is estimated to be 3–10 mb. Parameterizing the photoproduction cross section of η ′ -mesons by σ ( A ) = σ 0 A α , a value of α = 0.84 ± 0.03 has been deduced.
Published: 2012

48. Erratum to: High-statistics study of the reaction $\gamma p\rightarrow p2\pi^{0}$

Author: V. Metag, S. Lugert, Eberhard Klempt, T. Seifen, M. Kotulla, Alastair J. Wilson, Frank Klein, M. Ostrick, D. Walther, S. Kammer, Friedrich Klein, T. Mertens, H. Dutz, V. A. Nikonov, Ch. Funke, Herbert Löhner, J. G. Messchendorp, Lalit Mohan Pant, V. Crede, I. Horn, Frank Frommberger, S. Shende, A. Thiel, Ankhi Roy, Ch. Schmidt, V. Sokhoyan, R. Ewald, B. Krusche, H. Pee, O. Bartholomy, M. Pfeiffer, T. Szczepanek, E. Gutz, B. Bantes, H. Kalinowsky, Michael Fuchs, Yu. A. Beloglazov, D. Piontek, J. C. S. Bacelar, A. V. Sarantsev, B. Metsch, D. Trnka, I. V. Lopatin, Ch. Wendel, Matthew Lang, V. V. Sumachev, A. V. Anisovich, I. Jaegle, V. Kleber, R. Gregor, R. Varma, J. Junkersfeld, D. Elsner, R. W. Novotny, Ph. Hoffmeister, U. Thoma, R. Castelijns, H. Schmieden, D. E. Bayadilov, A. B. Gridnev, Mariana Nanova, A. Süle, Wolfgang Hillert, D. Novinsky, and R. Beck
Subjects: Physics, Baryon, Nuclear and High Energy Physics, Meson, Isospin, Partial wave analysis, Bremsstrahlung, Dalitz plot, Photon energy, Atomic physics, Nucleon
Abstract: The photoproduction of 2π$^{0}$ mesons off protons was studied with the Crystal Barrel/TAPS experiment at the electron accelerator ELSA in Bonn. The energy of photons produced in a radiator was tagged in the energy range from 600 MeV to 2.5 GeV. Differential and total cross sections and pπ$^{0}$ π$^{0}$ Dalitz plots are presented. Part of the data was taken with a diamond radiator producing linearly polarized photons, and beam asymmetries were derived. Properties of nucleon and Δ resonances contributing to the pπ$^{0}$ π$^{0}$ final state were determined within the Bonn-Gatchina (BnGa) partial-wave analysis. The data presented here allow us to determine branching ratios of nucleon and Δ resonances for their decays into pπ$^{0}$ π$^{0}$ via several intermediate states. Most prominent are decays proceeding via Δ(1232)π, N(1440)1/2$^{+}$ π, N(1520)3/2$^{−}$ π, N(1680)5/2$^{+}$ π, but also pf$_{0}$(500), pf$_{0}$(980), and pf$_{2}$(1270) contribute to the reaction.
Published: 2015

49. Photoproduction of meson pairs: First measurement of the polarization observable Is

Author: Matthew Lang, T. Mertens, Herbert Löhner, A. Suele, Michael Fuchs, V. Crede, D. Piontek, D. Walther, M. Pfeiffer, I. V. Lopatin, A. Thiel, V. Metag, Ch. Schmidt, H. Dutz, V. Sokhoyan, J. G. Messchendorp, M. Kotulla, J. C. S. Bacelar, Friedrich Klein, R. Beck, I. Jaegle, Winston Roberts, M. Ostrick, R. Gregor, R. Ewald, R. Castelijns, S. Schadmand, Ch. Weinheimer, H. Schmieden, R. Varma, D. E. Bayadilov, A. B. Gridnev, Mariana Nanova, D. Trnka, D. Elsner, T. Szczepanek, V. Kleber, R. W. Novotny, Ph. Hoffmeister, S. Kammer, B. Schoch, Ch. Funke, Lalit Mohan Pant, S. Lugert, Wolfgang Hillert, Eberhard Klempt, Ankhi Roy, V. A. Nikonov, D. Menze, I. Horn, A. V. Anisovich, Ch. Wendel, B. Bantes, V. V. Sumachev, Yu. A. Beloglazov, A. V. Sarantsev, H. Kalinowsky, B. Krusche, E. Gutz, D. V. Novinski, S. Shende, U. Thoma, H. van Pee, O. Bartholomy, J. Junkersfeld, Frank Frommberger, and Frank Klein
Subjects: Physics, Nuclear and High Energy Physics, Photon, Meson, Proton, Linear polarization, media_common.quotation_subject, Partial wave analysis, FOS: Physical sciences, Observable, Polarization (waves), Asymmetry, Nuclear physics, High Energy Physics::Experiment, Nuclear Experiment (nucl-ex), Nuclear Experiment, media_common
Abstract: The polarization observable I^s, a feature exclusive to the acoplanar kinematics of multi-meson final states produced via linearly polarized photons, has been measured for the first time. Results for the reaction g p -> p pi0 eta are presented for incoming photon energies between 970 MeV and 1650 MeV along with the beam asymmetry I^c. The comparably large asymmetries demonstrate a high sensitivity of I^s to the dynamics of the reaction. Fits using Bonn-Gatchina partial wave analysis demonstrate that the new polarization observables carry significant information on the contributing partial waves., 11 pages, 6 figures, v2 to appear in Phys. Lett. B
Published: 2010

50. Photoproduction of $ \eta$ -mesons off neutrons from a deuteron target

Author: B. Krusche, A. V. Sarantsev, V. A. Nikonov, Eberhard Klempt, A. V. Anisovich, U. Thoma, and I. Jaegle
Subjects: Physics, Nuclear and High Energy Physics, Particle physics, Meson, Partial wave analysis, Nuclear Theory, Helicity, High Energy Physics - Phenomenology, Formalism (philosophy of mathematics), Amplitude, Deuterium, High Energy Physics::Experiment, Neutron, Nuclear Experiment
Abstract: A formalism is developed for the partial wave analysis of data on meson photoproduction off deuterons and applied to photoproduction of $\eta$ and $\pi^0$ mesons. Different interpretations of a dip-bump structure of the $\eta$ photoproduction cross section in the 1670 MeV region are presented and discussed. Helicity amplitudes for two low-mass $S_{11}$ states are determined., Comment: 11 pages, 13 figures
Published: 2009

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