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16 results on '"S. Shende"'

1. 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

2. 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

3. 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
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4. 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
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5. 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
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6. High-statistics study of the reaction γp → p2π0

Author

S. Kammer, Ch. Funke, M. Kotulla, V. Crede, T. Szczepanek, E. Gutz, Alastair J. Wilson, H. Schmieden, Yu. A. Beloglazov, J. C. S. Bacelar, A. V. Sarantsev, D. E. Bayadilov, A. B. Gridnev, Mariana Nanova, Frank Frommberger, V. Sokhoyan, V. Metag, H. Kalinowsky, H. Dutz, A. V. Anisovich, J. G. Messchendorp, U. Thoma, O. Bartholomy, Friedrich Klein, V. A. Nikonov, M. Pfeiffer, Lalit Mohan Pant, M. Ostrick, J. Junkersfeld, T. Seifen, I. Horn, S. Lugert, Ch. Schmidt, Ch. Wendel, V. V. Sumachev, Eberhard Klempt, T. Mertens, Frank Klein, Herbert Löhner, Michael Fuchs, A. Thiel, D. Piontek, B. Metsch, Ankhi Roy, I. V. Lopatin, H. van Pee, B. Krusche, S. Shende, B. Bantes, Wolfgang Hillert, D. Elsner, R. W. Novotny, Ph. Hoffmeister, I. Jaegle, D. Walther, R. Ewald, R. Varma, V. Kleber, Matthew Lang, R. Gregor, D. Novinsky, R. Beck, D. Trnka, R. Castelijns, and A. Süle

Subjects
Nuclear physics, Physics, Nuclear and High Energy Physics, Range (particle radiation), Photon, Meson, law, Linear polarization, Partial wave analysis, Particle accelerator, Nucleon, Beam (structure), law.invention
Abstract

The photoproduction of 2$\pi^0$ 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 $p\pi^0\pi^0$ 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 $\Delta$ resonances contributing to the $p\pi^0\pi^0$ final state were determined within the BnGa partial wave analysis. The data presented here allow us to determine branching ratios of nucleon and $\Delta$ resonances for their decays into $p\pi^0\pi^0$ via several intermediate states. Most prominent are decays proceeding via $\Delta(1232)\pi$, $N(1440)1/2^+\pi$, $N(1520)3/2^-\pi$, $N(1680)5/2^+\pi$, but also $pf_0(500)$, $pf_0(980)$, and $pf_2(1270)$ contribute to the reaction.

Published
2015
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7. Erratum: Modification of theω-Meson Lifetime in Nuclear Matter [Phys. Rev. Lett.100, 192302 (2008)]

Author

M. Kotulla, A. Ehmanns, I. Jaegle, Ulrich Mosel, Gisela Anton, V. Metag, V. Crede, S. Hoeffgen, I. Fabry, R. W. Gothe, Yu. A. Beloglazov, T. Mertens, J. C. S. Bacelar, M. Konrad, S. Shende, J. G. Messchendorp, D. E. Bayadilov, E. Gutz, H. Dutz, J. Lotz, A. B. Gridnev, Mariana Nanova, J. Hoessl, O. Bartholomy, Michael Fuchs, D. Trnka, J. Langheinrich, R. Gregor, I. V. Lopatin, D. Elsner, R. W. Novotny, Ph. Hoffmeister, R. Castelijns, R. Ewald, K. Essig, S. Schadmand, S. Lugert, Eberhard Klempt, P. Muehlich, J. Junkersfeld, H. Loehner, Fritz Klein, I. Horn, D. Menze, B. Kopf, Ch. Funke, B. Krusche, H. Kalinowsky, R. Bogendoerfer, and Frank Klein

Subjects
Nuclear physics, Physics, Particle physics, Meson production, Meson, General Physics and Astronomy, Nuclear matter, Omega
Published
2015
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8. Photoproduction of omega mesons off protons and neutrons

Author

A. Süle, S. Höffgren, O. Bartholomy, M. Kotulla, Ankhi Roy, M. Konrad, Friedrich Klein, M. Ostrick, S. Schadmand, Matthew Lang, H. Dutz, M. Pfeiffer, J. C. S. Bacelar, V. Kleber, S. Shende, J. Junkersfeld, H. Schmieden, D. E. Bayadilov, V. Crede, H. Kalinowsky, R. Ewald, A. B. Gridnev, Mariana Nanova, I. Jaegle, A. V. Anisovich, Ch. Schmidt, T. Szczepanek, D. Menze, H. van Pee, S. Kammer, Frank Klein, R. Varma, F. Dietz, A. Wilson, I. V. Lopatin, T. Mertens, Herbert Löhner, U. Thoma, V. Shklyar, Ch. Wendel, Lalit Mohan Pant, Frank Frommberger, C. Funke, R. Beck, D. Walter, V. V. Sumachev, J. G. Messchendorp, R. W. Gothe, R. Castelijns, R. Gregor, D. Trnka, E. Gutz, V. Metag, B. Bantes, T. Rostomyan, V. A. Nikonov, I. Horn, S. Lugert, Eberhard Klempt, Y. A. Belogazov, D. Elsner, R. W. Novotny, Ph. Hoffmeister, B. Schoch, Wolfgang Hillert, B. Krusche, D. V. Novinski, and Research unit Nuclear & Hadron Physics

Subjects
Nuclear reaction, Physics, TAPS, Nuclear and High Energy Physics, Proton, Meson, Astrophysics::High Energy Astrophysical Phenomena, Hadron, Nuclear Theory, WIDTH, Photon energy, DEUTERON, Nuclear physics, Deuterium, NUCLEAR MEDIUM, Neutron, High Energy Physics::Experiment, PHI-PHOTOPRODUCTION, SPECTROMETER, Atomic physics, Nucleon, Nuclear Experiment, MATTER
Abstract

Omega photoproduction off hydrogen and deuterium has been studied with the tagged photon beam of the ELSA accelerator in Bonn for photon energies up to 2.0 GeV. The omega meson has been identified via the omega -> pi(0) gamma -> gamma gamma gamma decay mode, using the combined setup of the Crystal Barrel/TAPS detector systems. Both inclusive and exclusive analyses have been carried out. Differential and total cross-sections have been derived for omega mesons produced off free protons and off protons and neutrons bound in deuterium. The cross-section for the production off the bound neutron is found to be a factor of a parts per thousand 1.3 larger than the one off the bound proton in the incident beam energy region 1.2 GeV

Published
2015
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9. High statistics study of the reaction γp → pπ0 η

Author

E. Gutz, A. Süle, B. Bantes, S. Lugert, D. Elsner, R. Castelijns, R. W. Novotny, H. Schmieden, Ph. Hoffmeister, Eberhard Klempt, Frank Klein, B. Krusche, D. E. Bayadilov, A. B. Gridnev, O. Bartholomy, R. Gregor, M. Kotulla, Yu. A. Beloglazov, A. Wilson, J. C. S. Bacelar, A. V. Sarantsev, M. Ostrick, D. Trnka, Matthew Lang, T. Szczepanek, Ankhi Roy, A. V. Anisovich, Lalit Mohan Pant, Frank Frommberger, R. Varma, U. Thoma, M. Fuchs, V. Crede, D. Novinsky, V. Sokhoyan, J. Junkersfeld, V. Kleber, R. Beck, H. Dutz, Wolfgang Hillert, V. A. Nikonov, S. Shende, M. Pfeiffer, Ch. Wendel, S. Kammer, V. V. Sumachev, Ch. Funke, M. Nanova, I. Jaegle, R. Ewald, A. Thiel, I. Horn, H. van Pee, H. Kalinowsky, D. Walther, T. Mertens, Herbert Löhner, V. Metag, J. G. Messchendorp, D. Piontek, Ch. Schmidt, I. V. Lopatin, and Friedrich Klein

Subjects
Physics, Nuclear and High Energy Physics, Photon, Meson, 010308 nuclear & particles physics, Partial wave analysis, Nuclear Theory, Hadron, Dalitz plot, Electron, 01 natural sciences, Nuclear physics, 0103 physical sciences, Isobar, Nuclear Experiment, 010306 general physics, Nucleon
Abstract

Photoproduction off protons of the pπ 0 η three-body final state was studied with the Crystal Barrel/TAPS detector, at the electron stretcher accelerator ELSA in Bonn, for incident energies from the π 0 η production threshold up to 2.5 GeV. Differential cross sections and the total cross sections are presented. The use of linearly polarized photons gives access to the polarization observables Σ, I s , and I c , the latter two characterize beam asymmetries in case of three-body final states. Δ(1232)η, N(1535)1/2− π, and pa 0(980) are the dominant isobars contributing to the reaction. The partial wave analysis confirms the existence of some nucleon and Δ resonances, for which so far only fair evidence was reported. A large number of decay modes of known nucleon and Δ resonances is presented. It is shown that detailed investigations of decay branching ratios may provide a key to unravelling the structure of nucleon and Δ resonances.

Published
2014
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10. Photoproduction of Neutral Pions off Protons

Author

T. Mertens, Herbert Löhner, E. Gutz, V. A. Nikonov, H. Schmieden, Wolfgang Hillert, M. Ostrick, S. Schadmand, Frank Klein, D. E. Bayadilov, Yu. A. Beloglazov, H. Kalinowsky, A. V. Sarantsev, J. C. S. Bacelar, A. Wilson, A. B. Gridnev, D. V. Novinski, H. van Pee, R. Bantes, Mariana Nanova, V. Crede, N. Sparks, V. Sokhoyan, H. Dutz, A. Suele, D. Elsner, Ch. Schmidt, I. Jaegle, Frank Frommberger, R. Varma, R. Castelijns, R. W. Novotny, Ph. Hoffmeister, D. Menze, B. Krusche, R. Gregor, A. V. Anisovich, Friedrich Klein, Volker Metag, S. Shende, S. Kammer, B. Schoch, Ch. Wendel, C. Funke, V. V. Sumachev, M. Pfeiffer, O. Bartholomy, D. Walther, S. Lugert, L. M. Pant, M. Kotulla, Johannes Messchendorp, U. Thoma, Eberhard Klempt, J. Junkersfeld, A. Roy, I. V. Lopatin, R. Beck, R. Ewald, D. Trnka, T. Szczepanek, KVI - Center for Advanced Radiation Technology, and Research unit Nuclear & Hadron Physics

Subjects
Nuclear and High Energy Physics, Particle physics, N(2190), Photon, tagged beam [photon], Meson, 0.85-2.50 GeV, Partial wave analysis, electromagnetic [calorimeter], NUCLEON RESONANCE, FOS: Physical sciences, photoproduction [pi0], +p+pi0%22">photon p --> p pi0, Gamma gamma, REGION, High Energy Physics - Experiment, Nuclear physics, High Energy Physics - Experiment (hep-ex), Pion, High Energy Physics - Phenomenology (hep-ph), Pi, Bonn ELSA Stor, ddc:530, SPECTROMETER, NEAR-THRESHOLD, Nuclear Experiment (nucl-ex), Nuclear Experiment, AMPLITUDES, BARYON, Physics, N(2080), partial wave analysis, OPERATOR EXPANSION METHOD, Baryon, High Energy Physics - Phenomenology, Amplitude, exclusive reaction [photon p], angular dependence [differential cross section], STATES, High Energy Physics::Experiment, CROSS-SECTION, DECAY, small-angle, N(2070), experimental results, +2photon%22">pi0 --> 2photon
Abstract

Photoproduction of neutral pions has been studied with the CBELSA/TAPS detector in the reaction $\gamma p\to p\pi^0$ for photon energies between 0.85 and 2.50 GeV. The $\pi^0$ mesons are observed in their dominant neutral decay mode: $\pi^0\to\gamma\gamma$. For the first time, the differential cross sections cover the very forward region, $\theta_{\rm c.m.}, Comment: 12 pages, 9 figures, minor modifications to PWA section

Published
2011
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11. In-mediumωmass from theγ+Nb→π0γ+Xreaction

Author

V. Metag, M. Ostrick, M. Kotulla, Ch. Schmidt, A. Ehmanns, V. Crede, M. Pfeiffer, D. Elsner, R. Ewald, R. Bogendorfer, R. W. Novotny, Ph. Hoffmeister, Yu. A. Beloglazov, R. Gregor, T. Szczepanek, Friedrich Klein, B. Schoch, J. C. S. Bacelar, H. Schmieden, D. E. Bayadilov, I. Fabry, A. Radkov, A. B. Gridnev, Mariana Nanova, G. Suft, S. Shende, Michael Fuchs, D. Trnka, J. Langheinrich, J. Lotz, O. Bartholomy, H. Dutz, U. Thoma, Frank Klein, J. Hossl, S. Schadmand, R. Varma, I. V. Lopatin, R. W. Gothe, D. Walther, Ch. Weinheimer, H. van Pee, E. Gutz, J. Junkersfeld, J. G. Messchendorp, T. Mertens, Herbert Löhner, C. Morales, Lalit Mohan Pant, M. Konrad, B. Kopf, I. Jaegle, Gisela Anton, Ch. Funke, I. Horn, S. Lugert, Eberhard Klempt, S. Höffgen, B. Krusche, R. Castelijns, K. Essig, A. Süle, Ankhi Roy, D. Menze, Ch. Wendel, V. V. Sumachev, and H. Kalinowsky

Subjects
Absolute magnitude, Physics, Nuclear and High Energy Physics, Particle physics, Photon, Meson, Electron, Sensitivity (control systems), Nuclear Experiment, Nuclear matter, Omega, Line (formation)
Abstract

Data on the photoproduction of $\ensuremath{\omega}$ mesons on nuclei have been reanalyzed in a search for in-medium modifications. The data were taken with the crystal barrel (CB)/two-arm photon spectrometer (TAPS) detector system at the ELectron Stretcher Anlage (ELSA) accelerator facility in Bonn. First results from the analysis of the data set were published by Trnka et al. [Phys. Rev. Lett. 94, 192303 (2005)], claiming a lowering of the $\ensuremath{\omega}$ mass in the nuclear medium by 14$%$ at normal nuclear matter density. The extracted $\ensuremath{\omega}$ line shape was found to be sensitive to the background subtraction. For this reason a reanalysis of the same data set has been initiated, and a new method has been developed to reduce the background and to determine the shape and absolute magnitude of the background directly from the data. Details of the reanalysis and of the background determination are described. The $\ensuremath{\omega}$ signal on the Nb target, extracted in the reanalysis, does not show a deviation from the corresponding line shape on a ${\mathrm{LH}}_{2}$ target, measured as reference. The earlier claim of an in-medium mass shift is thus not confirmed. The sensitivity of the $\ensuremath{\omega}$ line shape to different in-medium modification scenarios is discussed.

Published
2010
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12. Measurement of the beam asymmetryΣin the forward direction forγ⃗p→pπ0

Author

O. Bartholomy, V. A. Nikonov, S. Lugert, Eberhard Klempt, H. Schmieden, D. E. Bayadilov, T. Mertens, E. Gutz, A. B. Gridnev, Mariana Nanova, Herbert Löhner, D. Elsner, R. Castelijns, Yu. A. Beloglazov, H. van Pee, H. Kalinowsky, J. C. S. Bacelar, A. V. Sarantsev, N. Sparks, R. W. Novotny, Ph. Hoffmeister, B. Krusche, D. Menze, Friedrich Klein, S. Kammer, I. Jaegle, C. Funke, Ch. Schmidt, Ch. Wendel, B. Schoch, V. V. Sumachev, L. M. Pant, A. Roy, R. Bantes, S. Shende, D. V. Novinski, V. Sokhoyan, Volker Metag, R. Gregor, A. V. Anisovich, U. Thoma, J. G. Messchendorp, D. Walther, S. Schadmand, J. Junkersfeld, R. Ewald, I. V. Lopatin, Wolfgang Hillert, R. Beck, D. Trnka, M. Kotulla, T. Szczepanek, R. Varma, A. Süle, M. Ostrick, V. Crede, Frank Klein, A. Wilson, M. Pfeiffer, and Frank Frommberger

Subjects
Physics, Nuclear and High Energy Physics, Particle physics, Photon, Meson, media_common.quotation_subject, Hadron, Sigma, Elementary particle, Asymmetry, Nuclear physics, Pion, High Energy Physics::Experiment, Nuclear Experiment, Lepton, media_common
Abstract

Photoproduction of neutral pions has been studied with the CBELSA/TAPS detector for photon energies between 0.92 and 1.68 GeV at the electron stretcher accelerator ELSA. The beam asymmetry Sigma has been extracted for 115 degrees > theta(c.m.) > 155 degrees of the pi(0) meson and for theta(c.m.) > 60 degrees. The new beam-asymmetry data cover the very forward region, which extend previously published data for the same reaction by our collaboration and improve the world database for photon energies above 1.5 GeV. The angular dependence of Sigma shows overall good agreement with the SAID parametrization.

Published
2010
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13. Photoproduction ofηandη'mesons off protons

Author

V. Crede, A. McVeigh, A. V. Anisovich, J. C. S. Bacelar, R. Bantes, O. Bartholomy, D. Bayadilov, R. Beck, Y. A. Beloglazov, R. Castelijns, A. Ehmanns, D. Elsner, K. Essig, R. Ewald, I. Fabry, M. Fuchs, Chr. Funke, R. Gothe, R. Gregor, A. Gridnev, E. Gutz, St. Höffgen, P. Hoffmeister, I. Horn, I. Jaegle, J. Junkersfeld, H. Kalinowsky, S. Kammer, Frank Klein, Friedrich Klein, E. Klempt, M. Konrad, M. Kotulla, B. Krusche, J. Langheinrich, H. Löhner, I. V. Lopatin, J. Lotz, S. Lugert, D. Menze, T. Mertens, J. G. Messchendorp, V. Metag, M. Nanova, V. A. Nikonov, D. Novinski, R. Novotny, M. Ostrick, L. M. Pant, H. van Pee, M. Pfeiffer, A. Roy, A. V. Sarantsev, S. Schadmand, C. Schmidt, H. Schmieden, B. Schoch, S. Shende, V. Sokhoyan, N. Sparks, A. Süle, V. V. Sumachev, T. Szczepanek, U. Thoma, D. Trnka, R. Varma, D. Walther, Ch. Weinheimer, Ch. Wendel, and A. Wilson

Subjects
Physics, Nuclear and High Energy Physics, Angular range, Particle physics, Photon, Meson, Proton, Nuclear Theory, Eta meson, Gamma gamma, Baryon, Nuclear physics, High Energy Physics::Experiment, Nuclear Experiment
Abstract

Total and differential cross sections for eta and eta(')photoproduction off the proton have been determined with the CBELSA/TAPS detector for photon energies between 0.85 and 2.55 GeV. The eta mesons are detected in their two neutral decay modes, eta ->gamma gamma and eta -> 3 pi(0)-> 6 gamma, and for the first time, cover the full angular range in cos theta(c.m.) of the eta meson. These new eta photoproduction data are consistent with the earlier CB-ELSA results. The eta(') mesons are observed in their neutral decay to pi(0)pi(0)eta -> 6 gamma and also extend the coverage in angular range.

Published
2009
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14. Beam asymmetries in near-thresholdωphotoproduction off the proton

Author

V. Sokhoyan, Matthew Lang, M. Pfeiffer, D. Walther, A. Ehmanns, J. Junkersfeld, R. Varma, Ch. Weinheimer, S. Shende, Friedrich Klein, M. Ostrick, H. Kalinowsky, H. Dutz, Frank Klein, A. Roy, R. Beck, D. Elsner, D. Menze, V. Metag, E. Gutz, V. Crede, Ph. Hoffmeister, H. Schmieden, I. Jaegle, D. E. Bayadilov, S. Kammer, A. B. Gridnev, H. van Pee, Mariana Nanova, Ch. Wendel, V. Kleber, Ch. Funke, Yu. A. Beloglazov, R. Castelijns, A. Suele, V. V. Sumachev, A. V. Sarantsev, O. Bartholomy, M. Kotulla, K. Essig, M. Konrad, D. Trnka, R. Novotny, S. Hoeffgen, I. V. Lopatin, T. Mertens, A. V. Anisovich, U. Thoma, Herbert Löhner, B. Bantes, C. Morales, B. Schoch, A. Radkov, J. G. Messchendorp, I. Fabry, J. C. S. Bacelar, R. Gregor, R. Ewald, T. Szczepanek, M. Fuchs, V. A. Nikonov, I. Horn, S. Lugert, Eberhard Klempt, Ch. Schmidt, J. Lotz, D. V. Novinski, B. Krusche, L. M. Pant, Research unit Nuclear & Hadron Physics, and Publica

Subjects
TAPS, Physics, Nuclear and High Energy Physics, Photon, Proton, Meson, media_common.quotation_subject, photon, Nuclear Theory, Bremsstrahlung, Resonance, PHOTONS, MESONS, ETA, Omega, Asymmetry, Nuclear physics, Pion, SPECTROMETER, High Energy Physics::Experiment, Atomic physics, Nuclear Experiment, media_common
Abstract

The photoproduction of {omega} mesons off protons has been studied at the Bonn ELSA accelerator from threshold to E{sub {gamma}}=1700 MeV. Linearly polarized beams were produced via coherent bremsstrahlung. Large photon asymmetries in excess of 50% were obtained. For the first time the pion asymmetries associated with the {omega}{yields}{pi}{sup 0}{gamma} decay were measured and found close to zero. The asymmetries indicate s-channel resonance formation on top of t-channel exchange processes.

Published
2008
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15. Modification of the omega-meson lifetime in nuclear matter

Author

R. W. Novotny, Ph. Hoffmeister, B. Schoch, J. C. S. Bacelar, D. Menze, D. Elsner, R. Ewald, A. Radkov, T. Mertens, M. Kotulla, H. Dutz, B. Kopf, Ch. Wendel, A. Suele, V. V. Sumachev, D. Trnka, J. Langheinrich, I. Horn, T. Szczepanek, J. Hoessl, I. Jaegle, Gisela Anton, Fritz Klein, M. Ostrick, R. Castelijns, E. Gutz, Volker Metag, S. Lugert, S. Hoeffgen, R. W. Gothe, M. Fuchs, H. van Pee, Eberhard Klempt, K. Essig, Ch. Funke, J. Lotz, H. Kalinowsky, M. Konrad, V. Crede, B. Krusche, S. Shende, Frank Klein, Yu. A. Beloglazov, L. M. Pant, A. Ehmanns, Ch. Weinheimer, M. Pfeiffer, J. G. Messchendorp, O. Bartholomy, H. Schmieden, S. Schadmand, U. Mosel, D. E. Bayadilov, A. B. Gridnev, Mariana Nanova, Ch. Schmidt, I. V. Lopatin, G. Suft, R. Bogendoerfer, U. Thoma, D. Walther, P. Muehlich, R. Gregor, I. Fabry, J. Junkersfeld, A. Roy, H. Loehner, R. Varma, KVI - Center for Advanced Radiation Technology, and Publica

Subjects
TAPS, Particle physics, Meson, Nuclear Theory, Hadron, General Physics and Astronomy, Omega, Nuclear physics, ATTENUATION, QCD SUM-RULES, SPECTROMETER, Nuclear Experiment, Mass number, Physics, IN-MEDIUM, Nuclear matter, Omega baryon, Baryon, High Energy Physics - Phenomenology, PHOTON, High Energy Physics::Experiment, PHI-PHOTOPRODUCTION, Glauber, VECTOR-MESONS
Abstract

The photo production of $\omega$ mesons on the nuclei C, Ca, Nb and Pb has been measured using the Crystal Barrel/TAPS detector at the ELSA tagged photon facility in Bonn. The dependence of the $\omega$ meson cross section on the nuclear mass number has been compared with three different types of models, a Glauber analysis, a BUU analysis of the Giessen theory group and a calculation by the Valencia theory group. In all three cases, the inelastic $\omega$ width is found to be $130-150 \rm{MeV/c^2}$ at normal nuclear matter density for an average 3-momentum of 1.1 GeV/c. In the restframe of the $\omega$ meson, this inelastic $\omega$ width corresponds to a reduction of the $\omega$ lifetime by a factor $\approx 30$. For the first time, the momentum dependent $\omega$N cross section has been extracted from the experiment and is in the range of 70 mb., Comment: 5 pages, 4 figures

Published
2007

16. Observation of In-Medium Modifications of theωMeson

Author

V. Crede, V. Metag, I. Fabry, Yu. A. Beloglazov, Lalit Mohan Pant, R. W. Gothe, S. Lugert, H. Dutz, J. Hossl, Eberhard Klempt, S. Höffgen, R. Varma, R. Castelijns, Fritz Klein, I. Horn, M. Ostrick, G. Suft, S. Shende, I. Jaegle, M. Kotulla, T. Mertens, R. Gregor, S. Schadmand, Herbert Löhner, A. Roy, Gisela Anton, O. Bartholomy, Ch. Schmidt, C. Morales, J. Lotz, D. Trnka, J. Langheinrich, H. Kalinowsky, D. Walther, T. Szczepanek, Frank Klein, K. Essig, A. Süle, E. Gutz, B. Kopf, B. Krusche, A. Radkov, A. Ehmanns, H. van Pee, M. Pfeiffer, Ch. Funke, D. Menze, D. Elsner, M. Konrad, H. Schmieden, D. E. Bayadilov, Ch. Wendel, A. B. Gridnev, Mariana Nanova, V. V. Sumachev, U. Thoma, R. W. Novotny, Ph. Hoffmeister, J. C. S. Bacelar, B. Schoch, J. Junkersfeld, R. Ewald, R. Bogendorfer, J. G. Messchendorp, Michael Fuchs, I. V. Lopatin, and Ch. Weinheimer

Subjects
Physics, Particle physics, Meson, Nuclear Theory, Hadron, General Physics and Astronomy, Omega baryon, Omega, Baryon, Nuclear physics, Particle decay, Pion, High Energy Physics::Experiment, Nuclear Experiment, Nuclear density
Abstract

The photoproduction of omega mesons on nuclei has been investigated using the Crystal Barrel/TAPS experiment at the ELSA tagged photon facility in Bonn. The aim is to study possible in-medium modifications of the omega meson via the reaction gamma+A

Published
2005
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