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232 results on '"Kammer, S."'

1. New data on $\vec{\gamma} \vec{p}\rightarrow \eta p$ with polarized photons and protons and their implications for $N^* \to N\eta$ decays

Author

Müller, J., Hartmann, J., Grüner, M., Afzal, F., Anisovich, A. V., Bantes, B., Bayadilov, D., Beck, R., Becker, M., Beloglazov, Y., Berlin, M., Bichow, M., Böse, S., Brinkmann, K. -T., Challand, T., Crede, V., Dietz, F., Dieterle, M., Drexler, P., Dutz, H., Eberhardt, H., Elsner, D., Ewald, R., Fornet-Ponse, K., Friedrich, S., Frommberger, F., Funke, C., Gottschall, M., Gridnev, A., Goertz, S., Gutz, E., Hammann, C., Hannen, V., Hannappel, J., Herick, J., Hillert, W., Hoffmeister, P., Honisch, C., Jahn, O., Jude, T., Jaegle, I., Käser, A., Kaiser, D., Kalinowsky, H., Kalischewski, F., Kammer, S., Keshelashvili, I., Klassen, P., Kleber, V., Klein, F., Klempt, E., Koop, K., Krusche, B., Kube, M., Lang, M., Lopatin, I., Maghrbi, Y., Mahlberg, P., Makonyi, K., Messi, F., Metag, V., Meyer, W., Müllers, J., Nanova, M., Nikonov, V., Novinski, D., Novotny, R., Piontek, D., Reicherz, G., Rosenbaum, C., Rostomyan, T., Roth, B., Sarantsev, A., Schmidt, C., Schmieden, H., Schmitz, R., Seifen, T., Sokhoyan, V., Thiel, A., Thoma, U., Urban, M., van Pee, H., Walther, D., Wendel, C., Wiedner, U., Wilson, A., Winnebeck, A., Witthauer, L., and Collaboration, CBELSA/TAPS

Subjects
Nuclear Experiment
Abstract

The polarization observables $T, E, P, H$, and $G$ in photoproduction of $\eta$ 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, J\"uBo, and BnGa partial-wave analyses. A refit within the BnGa approach including further data yields precise branching ratios for the $N\eta$ decay of nucleon resonances. A $N\eta$-branching ratio of $0.33\pm 0.04$ for $N(1650)1/2^-$ is found, which reduces the large and controversially discussed $N\eta$-branching ratio difference of the two lowest mass $J^P=1/2^-$-resonances significantly., Comment: 10 pages, 11 figures

Published
2019
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2. Measurement of the Helicity Asymmetry $E$ for the reaction $ \gamma p\to \pi^0 p$

Author

collaboration, CBELSA/TAPS, Gottschall, M., Afzal, F., Anisovich, A. V., Bayadilov, D., Beck, R., Bichow, M., Brinkmann, K. -Th., Crede, V., Dieterle, M., Dietz, F., Dutz, H., Eberhardt, H., Elsner, D., Ewald, R., Fornet-Ponse, K., Friedrich, St., Frommberger, F., Gridnev, A., Grüner, M., Gutz, E., Hammann, Ch., Hannappel, J., Hartmann, J., Hillert, W., Hoffmeister, Ph., Honisch, Ch., Jude, T., Kammer, S., Kalinowsky, H., Keshelashvili, I., Klassen, P., Klein, F., Klempt, E., Koop, K., Krusche, B., Kube, M., Lang, M., Lopatin, I., Mahlberg, P., Makonyi, K., Metag, V., Meyer, W., Müller, J., Müllers, J., Nanova, M., Nikonov, V., Novotny, R., Piontek, D., Reicherz, G., Rostomyan, T., Sarantsev, A., Schmidt, Ch., Schmieden, H., Seifen, T., Sokhoyan, V., Spieker, K., Thiel, A., Thoma, U., Urban, M., van Pee, H., Walther, D., Wendel, Ch., Werthmüller, D., Wiedner, U., Wilson, A., Winnebeck, A., Witthauer, L., and Wunderlich, Y.

Subjects
Nuclear Experiment
Abstract

A measurement of the double-polarization observable $E$ for the reaction $\gamma p\to \pi^0 p$ is reported. The data were taken with the CBELSA/TAPS experiment at the ELSA facility in Bonn using the Bonn frozen-spin butanol (C$_4$H$_9$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 $E_\gamma =600$~MeV to $E_\gamma =2310$~MeV and nearly the complete angular range. The results are compared to and have been included in recent partial wave analyses., Comment: 21 pages

Published
2019

3. Photoproduction of eta mesons from the neutron: cross sections and double polarization observable E

Author

Witthauer, L., Dieterle, M., Afzal, F., Anisovich, A. V., Bantes, B., Bayadilov, D., Beck, R., Bichow, M., Brinkmann, K. -T., Böse, S., Challand, Th., Crede, V., Dutz, H., Eberhardt, H., Elsner, D., Ewald, R., Fornet-Ponse, K., Friedrich, St., Frommberger, F., Funke, Ch., Goertz, St., Gottschall, M., Gridnev, A., Grüner, M., Gutzınst, E., Hammann, D., Hammann, Ch., Hannappel, J., Hartmann, J., Hillert, W., Hoffmeister, Ph., Honisch, Ch., Jude, T., Kaiser, D., Kalinowsky, H., Kalischewski, F., Kammer, S., Käser, A., Keshelashvili, I., Klassen, P., Kleber, V., Klein, F., Koop, K., Krusche, B., Lang, M., Lopatin, I., Mahlberg, Ph., Makonyi, K., Metag, V., Meyer, W., Müller, J., Müllers, J., Nanova, M., Nikonov, V., Piontek, D., Reicherz, G., Rostomyan, T., Sarantsev, A., Schmidt, Ch., Schmieden, H., Seifen, T., Sokhoyan, V., Spieker, K., Thiel, A., Thoma, U., Urban, M., van Pee, H., Walford, N. K., Walther, D., Wendel, Ch., Werthmüller, D., Wilson, A., and Winnebeck, A.

Subjects
Nuclear Experiment
Abstract

Photoproduction of $\eta$ mesons from neutrons} \abstract{Results from measurements of the photoproduction of $\eta$ mesons from quasifree protons and neutrons are summarized. The experiments were performed with the CBELSA/TAPS detector at the electron accelerator ELSA in Bonn using the $\eta\to3\pi^{0}\to6\gamma$ decay. A liquid deuterium target was used for the measurement of total cross sections and angular distributions. The results confirm earlier measurements from Bonn and the MAMI facility in Mainz about the existence of a narrow structure in the excitation function of $\gamma n\rightarrow n\eta$. The current angular distributions show a forward-backward asymmetry, which was previously not seen, but was predicted by model calculations including an additional narrow $P_{11}$ state. Furthermore, data obtained with a longitudinally polarized, deuterated butanol target and a circularly polarized photon beam were analyzed to determine the double polarization observable $E$. Both data sets together were also used to extract the helicity dependent cross sections $\sigma_{1/2}$ and $\sigma_{3/2}$. The narrow structure in the excitation function of $\gamma n\rightarrow n\eta$ appears associated with the helicity-1/2 component of the reaction.

Published
2017
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4. Double-polarization observable G in neutral-pion photoproduction off the proton

Author

Thiel, A., Eberhardt, H., Lang, M., Afzal, F., Anisovich, A. V., Bantes, B., Bayadilov, D., Beck, R., Bichow, M., Brinkmann, K. -T., Böse, S., Crede, V., Dieterle, M., Dutz, H., Elsner, D., Ewald, R., Fornet-Ponse, K., Friedrich, St., Frommberger, F., Funke, Ch., Goertz, St., Gottschall, M., Gridnev, A., Grüner, M., Gutz, E., Hammann, D., Hammann, Ch., Hannappel, J., Hartmann, J., Hillert, W., Hoffmeister, Ph., Honisch, Ch., Jude, T., Kaiser, D., Kalinowsky, H., Kalischewski, F., Kammer, S., Keshelashvili, I., Klassen, P., Kleber, V., Klein, F., Klempt, E., Koop, K., Krusche, B., Kube, M., Lopatin, I., Mahlberg, Ph., Makonyi, K., Metag, V., Meyer, W., Müller, J., Müllers, J., Nanova, M., Nikonov, V., Piontek, D., Reeve, S., Reicherz, G., Runkel, S., Sarantsev, A., Schmidt, Ch., Schmieden, H., Seifen, T., Sokhoyan, V., Spieker, K., Thoma, U., Urban, M., van Pee, H., Walther, D., Wendel, Ch., Wilson, A., Winnebeck, A., and Witthauer, L.

Subjects
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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5. High statistics study of the reaction $\gamma p\to p\;2\pi^0$

Author

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

Subjects
Nuclear Experiment
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., Comment: 28 pages, 17 figures, 7 tables

Published
2015
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6. Measurement of double polarisation asymmetries in $\omega$-photoproduction

Author

Eberhardt, H., Jude, T. C., Schmieden, H., Anisovich, A. V., Bantes, B., Bayadilov, D., Beck, R., Beloglazov, Yu., Bichow, M., Boese, S., Brinkmann, K. -Th., Challand, Th., Crede, V., Diez, F., Drexler, P., Dutz, H., Elsner, D., Ewald, R., Fornet-Ponse, K., Friedrich, St., Frommberger, F., Funke, Ch., Gottschall, M., Gridnev, A., Gruener, M., Gutz, E., Hammann, Ch., Hannappel, J., Hartmann, J., Hillert, W., Hoffmeister, Ph., Honisch, Ch., Jaegle, I., Kaiser, D., Kalinowsky, H., Kalischewski, F., Kammer, S., Keshelashvili, I., Kleber, V., Klein, F., Klempt, E., Koop, K., Krusche, B., Kube, M., Lang, M., Lopatin, I., Maghrbi, Y., Makonyi, K., Metag, V., Meyer, W., Mueller, J., Nanova, M., Nikonov, V., Novotny, R., Piontek, D., Reeve, S., Reicherz, G., Rostomyan, T., Runkel, S., Sarantsev, A., Schaepe, St., Schmidt, Ch., Schmitz, R., Seifen, T., Sokhoyan, V., Sumachev, V., Thiel, A., Thoma, U., Urban, M., van Pee, H., Walther, D., Wendel, Ch., Wiedner, U., Wilson, A., and Winnebeck, A.

Subjects
Nuclear Experiment
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 $1108 < E_\gamma <1300$~MeV. Both measurements cover the full solid angle. The observables $E$ and $G$ are highly sensitive to the contribution of baryon resonances, with $E$ acting as a helicity filter in the $s$-channel. The new results indicate significant $s$-channel resonance contributions together with contributions from $t$-channel exchange processes. A partial wave analysis reveals strong contributions from the partial waves with spin-parity $J^P=3/2^+, 5/2^+$, and $3/2^-$., Comment: 6 pages, 6 figures

Published
2015
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7. Experimental constraints on the $\omega$-nucleus real potential

Author

Friedrich, S., Makonyi, K., Metag, V., Bayadilov, D., Bantes, B., Beck, R., Beloglazov, Y. A., Böse, S., Brinkmann, K. -T., Challand, Th., Crede, V., Dahlke, T., Dietz, F., Drexler, P., Eberhardt, H., Elsner, D., Ewald, R., Fornet-Ponse, K., Frommberger, F., Funke, Ch., Gottschall, M., Gridnev, A., Grüner, M., Gutz, E., Hammann, Ch., Hammann, D., Hannappel, J., Hartmann, J., Hillert, W., Hirenzaki, S., Hoffmeister, P., Honisch, Ch., Jaegle, I., Kaiser, D., Kalinowsky, H., Kammer, S., Keshelashvili, I., Kleber, V., Klein, F., Krusche, B., Lang, M., Lopatin, I. V., Maghrbi, Y., Nanova, M., Nagahiro, H., Müller, J., Odenthal, T., Piontek, D., Rostomyan, T., Schaepe, S., Schmidt, Ch., Schmieden, H., Schmitz, R., Seifen, T., Thiel, A., Thoma, U., van Pee, H., Walther, D., Weil, J., Wendel, Ch., Wiedner, U., Wilson, A., Winnebeck, A., and Zenke, F.

Subjects
Nuclear Experiment
Abstract

In a search for $\omega$ mesic states, the production of $\omega$-mesons in coincidence with forward going protons has been studied in photon induced reactions on $^{12}$C for incident photon energies of 1250 - 3100 MeV. The $\pi^0 \gamma$ pairs from decays of bound or quasi-free $\omega$-mesons have been measured with the CBELSA/TAPS detector system in coincidence with protons registered in the MiniTAPS forward array. Structures in the total energy distribution of the $\pi^0 \gamma$ pairs, which would indicate the population and decay of bound $\omega~^{11}$B states, are not observed. The $\pi^0 \gamma$ cross section of 0.3 nb/MeV/sr observed in the bound state energy regime between -100 and 0 MeV may be accounted for by yield leaking into the bound state regime because of the large in-medium width of the $\omega$-meson. A comparison of the measured total energy distribution with calculations suggests the real part $V_0$ of the $\omega~^{11}$B potential to be small and only weakly attractive with $V_0(\rho=\rho_0) = -15\pm$ 35(stat) $\pm$20(syst) MeV in contrast to some theoretical predictions of attractive potentials with a depth of 100 - 150 MeV., Comment: 13 pages, 8 figures

Published
2014
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8. Measurement of polarisation observables in $K^0_s\Sigma^+$ photoproduction off the proton

Author

Ewald, R., Anisovich, A. V., Bantes, B., Bartholomy, O., Bayadilov, D., Beck, R., Beloglazov, Y. A., Brinkmann, K. -T., Crede, V., Dutz, H., Elsner, D., Fornet-Ponse, K., Frommberger, F., Funke, Ch., Gridnev, A. B., Gutz, E., Hannappel, J., Hillert, W., Hoffmeister, P., Jaegle, I., Jahn, O., Jude, T. C, Junkersfeld, J., Kalinowsky, H., Kammer, S., Kleber, V., Klein, Frank, Klein, Friedrich, Klempt, E., Krusche, B., Lang, M., Löhner, H., Lopatin, I. V., Menze, D., Mertens, T., Messchendorp, J. G., Metag, V., Nanova, M., Nikonov, V. A., Novinski, D., Novotny, R., Ostrick, M., Pant, L., van Pee, H., Roy, A., Sarantsev, A. V., Schadmand, S., Schmidt, C., Schmieden, H., Schoch, B., Shende, S., Sokhoyan, V., Süle, A., Sumachev, V. V., Szczepanek, T., Thoma, U., Trnka, D., Varma, R., Walther, D., and Wendel, Ch.

Subjects
Nuclear Experiment
Abstract

The reaction $\gamma \, p \rightarrow K^0_S\,\Sigma^+$ 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 $E_\gamma = 2250$ MeV. In addition, the recoil hyperon polarisation was determined through the asymmetry in the weak decay $\Sigma^+ \rightarrow p \pi^0$ up to $E_\gamma = 1650$ MeV. The data are compared to partial wave analyses, and the possible impact on the interpretation of a recently observed cusp-like structure near the $K^*$ thresholds is discussed., Comment: 6 pages, 5 figures. References [8,9,10,11] which were not on the original submission are now included

Published
2014
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9. First measurement of the helicity asymmetry for $\gamma p\rightarrow p\pi^0$ in the resonance region

Author

Gottschall, M., Anisovich, A. V., Bantes, B., Bayadilov, D., Beck, R., Bichow, M., Böse, S., Brinkmann, K. -Th., Challand, Th., Crede, V., Dietz, F., Dutz, H., Eberhardt, H., Elsner, D., Ewald, R., Fornet-Ponse, K., Friedrich, St., Frommberger, F., Funke, Ch., Gridnev, A., Grüner, M., Gutz, E., Hammann, Ch., Hannappel, J., Hartmann, J., Hillert, W., Hoffmeister, Ph., Honisch, Ch., Jaegle, I., Kaiser, D., Kalinowsky, H., Kammer, S., Keshelashvili, I., Klein, F., Klempt, E., Koop, K., Krusche, B., Kube, M., Lang, M., Lopatin, I., Maghrbi, Y., Makonyi, K., Metag, V., Meyer, W., Müller, J., Nanova, M., Nikonov, V., Novotny, R., Piontek, D., Reicherz, G., Rostomyan, T., Sarantsev, A., Schaepe, St., Schmidt, Ch., Schmieden, H., Schmitz, R., Seifen, T., Sokhoyan, V., Thiel, A., Thoma, U., Urban, M., van Pee, H., Walther, D., Wendel, Ch., Wiedner, U., Wilson, A., and Winnebeck, A.

Subjects
Nuclear Experiment
Abstract

The first measurement of the helicity dependence of the photoproduction cross section of single neutral pions off protons is reported for photon energies from 600 to 2300\,MeV, covering nearly the full solid angle. The data are compared to predictions from the SAID, MAID, and BnGa partial wave analyses. Strikingly large differences between data and predictions are observed which are traced to differences in the helicity amplitudes of well known and established resonances. Precise values for the helicity amplitudes of several resonances are reported.

Published
2013
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10. Determination of the {\eta}'-nucleus optical potential

Author

Nanova, M., Metag, V., Paryev, E. Ya., Bayadilov, D., Bantes, B., Beck, R., Beloglazov, Y. A., Böse, S., Brinkmann, K. -T., Challand, Th., Crede, V., Dahlke, T., Dietz, F., Drexler, P., Eberhardt, H., Elsner, D., Ewald, R., Fornet-Ponse, K., Friedrich, S., Frommberger, F., Funke, Ch., Gottschall, M., Gridnev, A., Grüner, M., Gutz, E., Hammann, Ch., Hammann, D., Hannappel, J., Hartmann, J., Hillert, W., Hoffmeister, P., Honisch, Ch., Jaegle, I., Kaiser, D., Kalinowsky, H., Kammer, S., Keshelashvili, I., Kleber, V., Klein, F., Klempt, E., Krusche, B., Lang, M., Lopatin, I. V., Maghrbi, Y., Makonyi, K., Müller, J., Odenthal, T., Piontek, D., Schaepe, S., Schmidt, Ch., Schmieden, H., Schmitz, R., Seifen, T., Thiel, A., Thoma, U., van Pee, H., Walther, D., Wendel, Ch., Wiedner, U., Wilson, A., Winnebeck, A., and Zenke, F.

Subjects
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
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11. Well-established nucleon resonances revisited by double-polarization measurements

Author

Thiel, A., Anisovich, A. V., Bayadilov, D., Bantes, B., Beck, R., Beloglazov, Yu., Bichow, M., Böse, S., Brinkmann, K. -Th., Challand, Th., Crede, V., Dietz, F., Drexler, P., Dutz, H., Eberhardt, H., Elsner, D., Ewald, R., Fornet-Ponse, K., Friedrich, St., Frommberger, F., Funke, Ch., Gottschall, M., Grüner, M., Gutz, E., Hammann, Ch., Hannappel, J., Hartmann, J., Hillert, W., Hoffmeister, Ph., Honisch, Ch., Jaegle, I., Jürgensen, I., Kaiser, D., Kalinowsky, H., Kalischewski, F., Kammer, S., Keshelashvili, I., Kleber, V., Klein, F., Klempt, E., Krusche, B., Lang, M., Lopatin, I., Maghrbi, Y., Makonyi, K., Metag, V., Meyer, W., Müller, J., Nanova, M., Nikonov, V., Novotny, R., Piontek, D., Reicherz, G., Sarantsev, A., Schmidt, Ch., Schmieden, H., Seifen, T., Sokhoyan, V., Sumachev, V., Thoma, U., van Pee, H., Walther, D., Wendel, Ch., Wiedner, U., Wilson, A., Winnebeck, A., and Wunderlich, Y.

Subjects
Nuclear Experiment
Abstract

The first measurement is reported of the double-polarization observable G in photoproduction of neutral pions off protons, covering the photon energy range from 620 to 1120 MeV and the full solid angle. G describes the correlation between the photon polarization plane and the scattering plane for protons polarized along the direction of the incoming photon. The observable is highly sensitive to contributions from baryon resonances. The new results are compared to the predictions from SAID, MAID, and BnGa partial wave analyses. In spite of the long-lasting efforts to understand {\gamma}p -> p{\pi} 0 as the simplest photoproduction reaction, surprisingly large differences between the new data and the latest predictions are observed which are traced to different contributions of the N (1535) with spin-parity J^P = 1/2^- and N (1520) with J^P = 3/2^- . In the third resonance region, where N (1680) with J^P = 5/2^+ production dominates, the new data are reasonably close to the predictions., Comment: Submitted for publication in PRL

Published
2012
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12. Anomaly in the K^0_S Sigma^+ photoproduction cross section off the proton at the K* threshold

Author

Ewald, R., Anisovich, A. V., Bantes, B., Bartholomy, O., Bayadilov, D., Beck, R., Beloglazov, Y. A., Brinkmann, K. -T., Crede, V., Dutz, H., Elsner, D., Fornet-Ponse, K., Frommberger, F., Funke, Ch., Gridnev, A. B., Gutz, E., Hillert, W., Hannappel, J., Hoffmeister, P., Jaegle, I., Jahn, O., Jude, T., Junkersfeld, J., Kalinowsky, H., Kammer, S., Kleber, V., Klein, Frank, Klein, Friedrich, Klempt, E., Krusche, B., Lang, M., Löhner, H., Lopatin, I. V., Menze, D., Mertens, T., Messchendorp, J. G., Metag, V., Nanova, M., Nikonov, V. A., Novinski, D., Novotny, R., Ostrick, M., Pant, L., van Pee, H., Roy, A., Sarantsev, A. V., Schadmand, S., Schmidt, Ch., Schmieden, H., Schoch, B., Shende, S., Sokhoyan, V., Süle, A., Sumachev, V. V., Szczepanek, T., Thoma, U., Trnka, D., Varma, R., Walther, D., and Wendel, Ch.

Subjects
Nuclear Experiment
Abstract

The $\gamma + p \rightarrow K^0 + \Sigma^+$ photoproduction reaction is investigated in the energy region from threshold to $E_\gamma = 2250$\,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 $K^*\Lambda$ and $K^*\Sigma$ thresholds. It is speculated whether this signals the turnover of the reaction mechanism from t-channel exchange below the $K^*$ production threshold to an s-channel mechanism associated with the formation of a dynamically generated $K^*$-hyperon intermediate state., Comment: 14 pages, 7 figures

Published
2011
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13. Quasi-free photoproduction of eta-mesons off the deuteron

Author

Jaegle, I., Krusche, B., Anisovich, A. V., Bacelar, J. C. S., Bantes, B., Bartholomy, O., Bayadilov, D. E., Beck, R., Beloglazov, Y. A., Castelijns, R., Crede, V., Dieterle, M., Dutz, H., Elsner, D., Ewald, R., Frommberger, F., Funke, C., Gothe, R., Gregor, R., Gridnev, A. B., Gutz, E., Hillert, W., Hoeffgen, S., Hoffmeister, P., Horn, I., Junkersfeld, J., Kalinowsky, H., Kammer, S., Keshelashvili, I., Kleber, V., Klein, Frank, Klein, Friedrich, Klempt, E., Konrad, M., Kotulla, M., Lang, M., Loehner, H., Lopatin, I. V., Lugert, S., Maghrbi, Y., Menze, D., Mertens, T., Messchendorp, J. G., Metag, V., Nikonov, V. A., Nanova, M., Novinski, D. V., Novotny, R., Oberle, M., Ostrick, M., Pant, L. M., van Pee, H., Pfeiffer, M., Pheron, F., Roy, A., Sarantsev, A. V., Schadmand, S., Schmidt, C., Schmieden, H., Schoch, B., Shende, S. V., Sokhoyan, V., Suele, A., Sumachev, V. V., Szczepanek, T., Thoma, U., Trnka, D., Varma, R., Walther, D., Wendel, C., Werthmueller, D., and Witthauer, L.

Subjects
Nuclear Experiment
Abstract

Precise data for quasi-free photoproduction of $\eta$ mesons off the deuteron have been measured at the Bonn ELSA accelerator with the combined Crystal Barrel/TAPS detector for incident photon energies up to 2.5 GeV. The $\eta$-mesons have been detected in coincidence with recoil protons and neutrons. Possible nuclear effects like Fermi motion and re-scattering can be studied via a comparison of the quasi-free reaction off the bound proton to $\eta$-production off the free proton. No significant effects beyond the folding of the free cross section with the momentum distribution of the bound protons have been found. These Fermi motion effects can be removed by an analysis using the invariant mass of the $\eta$-nucleon pairs reconstructed from the final state four-momenta of the particles. The total cross section for quasi-free $\eta$-photoproduction off the neutron reveals even without correction for Fermi motion a pronounced bump-like structure around 1 GeV of incident photon energy, which is not observed for the proton. This structure is even narrower in the invariant mass spectrum of the $\eta$-neutron pairs. Position and width of the peak in the invariant mass spectrum are $W\approx 1665$ MeV and FWHM $\Gamma\approx 25$ MeV. The data are compared to the results of different models., Comment: accepted for publication in Eur. Phys. J. A

Published
2011
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14. Photoproduction of Neutral Pions off Protons

Author

Collaboration, The CBELSA/TAPS, Crede, V., Sparks, N., Wilson, A., Anisovich, A. V., Bacelar, J. C. S., Bantes, R., Bartholomy, O., Bayadilov, D., Beck, R., Beloglazov, Y. A., Castelijns, R., Dutz, H., Elsner, D., Ewald, R., Frommberger, F., Funke, Chr., Gregor, R., Gridnev, A., Gutz, E., Hillert, W., Hoffmeister, P., Jaegle, I., Junkersfeld, J., Kalinowsky, H., Kammer, S., Klein, Frank, Klein, Friedrich, Klempt, E., Kotulla, M., Krusche, B., Loehner, H., Lopatin, I. V., Lugert, S., Menze, D., Mertens, T., Messchendorp, J. G., Metag, V., Nanova, M., Nikonov, V. A., Novinski, D., Novotny, R., Ostrick, M., Pant, L. M., van Pee, H., Pfeiffer, M., Roy, A., Sarantsev, A. V., Schadmand, S., Schmidt, C., Schmieden, H., Schoch, B., Shende, S., Sokhoyan, V., Suele, A., Sumachev, V. V., Szczepanek, T., Thoma, U., Trnka, D., Varma, R., Walther, D., and Wendel, Ch.

Subjects
Nuclear Experiment, High Energy Physics - Experiment, High Energy Physics - Phenomenology
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, $\theta_{\rm c.m.}<60^\circ$. A partial-wave analysis of these data within the Bonn-Gatchina framework observes the high-mass resonances $G_{17}$(2190), $D_{13}$(2080), and $D_{15}$(2070)., Comment: 12 pages, 9 figures, minor modifications to PWA section

Published
2011
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15. Photoproduction of $\eta '$-mesons off the deuteron

Author

Jaegle, I., Mertens, T., Fix, A., Huang, F., Nakayama, K., Tiator, L., Anisovich, A. V., Bacelar, J. C. S., Bantes, B., Bartholomy, O., Bayadilov, D. E., Beck, R., Beloglazov, Y. A., Castelijns, R., Crede, V., Dutz, H., Elsner, D., Ewald, R., Frommberger, F., Funke, C., Gregor, R., Gridnev, A. B., Gutz, E., Hillert, W., Hoeffgen, S., Junkersfeld, J., Kalinowsky, H., Kammer, S., Kleber, V., Klein, Frank, Klein, Friedrich, Klempt, E., Kotulla, M., Krusche, B., Lang, M., Loehner, H., Lopatin, I. V., Lugert, S., Menze, D., Messchendorp, J. G., Metag, V., Nikonov, V. A., Nanova, M., Novinski, D. V., Novotny, R., Ostrick, M., Pant, L. M., van Pee, H., Pfeiffer, M., Roy, A., Sarantsev, A. V., Schadmand, S., Schmidt, C., Schmieden, H., Schoch, B., Shende, S. V., Sokhoyan, V., Suele, A., Sumachev, V. V., Szczepanek, T., Thoma, U., Trnka, D., Varma, R., Walther, D., and Wendel, C.

Subjects
Nuclear Experiment
Abstract

Quasi-free photoproduction of $\eta '$ 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 2.5 GeV. The $\eta '$-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 $\gamma n \rightarrow n\eta '$ reaction. In addition, also first estimates for coherent $\eta '$-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., Comment: Accepted for publication in Eur. Phys. J. A

Published
2010
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16. Measurement of the Beam Asymmetry $\Sigma$ in the Forward Direction for pi0 Photoproduction

Author

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

Subjects
Nuclear Experiment, High Energy Physics - Experiment
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 accelerator ELSA. The beam asymmetry~$\Sigma$ has been extracted for $115^\circ < \theta_{\rm c.m.} < 155^\circ$ of the $\pi^0$~meson and for $\theta_{\rm c.m.} < 60^\circ$. The new beam asymmetry data improve the world database for photon energies above 1.5~GeV and, by covering the very forward region, extend previously published data for the same reaction by our collaboration. The angular dependence of $\Sigma$ shows overall good agreement with the SAID parameterization., Comment: 11 pages, 10 figures, published in Phys. Rev. C, included LEPS data and MAID 2007 predictions for comparison with our data

Published
2010
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17. Photoproduction of meson pairs: First measurement of the polarization observable I^s

Author

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

Subjects
Nuclear Experiment
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., Comment: 11 pages, 6 figures, v2 to appear in Phys. Lett. B

Published
2009
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18. Photoproduction of $\eta$ and $\eta\prime$ Mesons off Protons

Author

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

Subjects
Nuclear Experiment
Abstract

Total and differential cross sections for $\eta$ and $\eta ^\prime$ 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, $\eta\to\gamma\gamma$ and $\eta\to 3\pi^0\to 6\gamma$, and for the first time, cover the full angular range in $\rm cos \theta_{cm}$ of the $\eta$ meson. These new $\eta$ photoproduction data are consistent with the earlier CB-ELSA results. The $\eta ^\prime$ mesons are observed in their neutral decay to $\pi^0\pi^0\eta\to 6\gamma$ and also extend the coverage in angular range., Comment: 13 pages, 21 figures, updated author list, submitted to PRC

Published
2009
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19. Photoproduction of eta-mesons off nuclei for Eg < 2.2 GeV

Author

Mertens, T., Jaegle, I., Muehlich, P., Bacelar, J. C. S., Bantes, B., Bartholomy, O., Bayadilov, D. E., Beck, R., Beloglazov, Y. A., Castelijns, R., Crede, V., Dutz, H., Ehmanns, A., Elsner, D., Essig, K., Ewald, R., Fabry, I., Fornet-Ponse, K., Fuchs, M., Funke, C., Gothe, R., Gregor, R., Gridnev, A. B., Gutz, E., Hoeffgen, S., Hoffmeister, P., Horn, I., Junkersfeld, J., Kalinowsky, H., Kammer, S., Kleber, V., Klein, Frank, Klein, Friedrich, Klempt, E., Konrad, M., Kotulla, M., Krusche, B., Lang, M., Langheinrich, J., Loehner, H., Lopatin, I. V., Lotz, J., Lugert, S., Menze, D., Messchendorp, J. G., Metag, V., Morales, C., Mosel, U., Nanova, M., Novinski, D. V., Novotny, R., Ostrick, M., Pant, L. M., van Pee, H., Pfeiffer, M., Radkov, A. K., Roy, A., Schadmand, S., Schmidt, C., Schmieden, H., Schoch, B., Shende, S., Sokhoyan, V., Suele, A., Sumachev, V. V., Szczepanek, T., Thoma, U., Trnka, D., Varma, R., Walther, D., Weinheimer, C., and Wendel, C.

Subjects
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
2008
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20. Quasi-free photoproduction of eta-mesons of the neutron

Author

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

Subjects
Nuclear Experiment
Abstract

Quasi-free photoproduction of eta-mesons off nucleons bound in the deuteron has been measured with the CBELSA/TAPS detector for incident photon energies up to 2.5 GeV at the Bonn ELSA accelerator. The eta-mesons have been detected in coincidence with recoil protons and recoil neutrons, which allows a detailed comparison of the quasi-free n(gamma,eta)n and p(gamma,eta)p reactions. The excitation function for eta-production off the neutron shows a pronounced bump-like structure at W=1.68 GeV (E_g ~ 1 GeV), which is absent for the proton., Comment: accepted for publication in Phys. Rev. Lett

Published
2008
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21. Measurement of the helicity asymmetry E for the reaction γp→π0p: The CBELSA/TAPS Collaboration

Author

Gottschall, M., Afzal, F., Anisovich, A. V., Bayadilov, D., Beck, R., Bichow, M., Brinkmann, K. Th., Crede, V., Dieterle, M., Dietz, F., Dutz, H., Eberhardt, H., Elsner, D., Ewald, R., Fornet-Ponse, K., Friedrich, St., Frommberger, F., Gridnev, A., Grüner, M., Gutz, E., Hammann, Ch., Hannappel, J., Hartmann, J., Hillert, W., Hoffmeister, Ph., Honisch, Ch., Jude, T., Kammer, S., Kalinowsky, H., Keshelashvili, I., Klassen, P., Klein, F., Klempt, E., Koop, K., Krusche, B., Kube, M., Lang, M., Lopatin, I., Mahlberg, P., Makonyi, K., Metag, V., Meyer, W., Müller, J., Müllers, J., Nanova, M., Nikonov, V., Novotny, R., Piontek, D., Reicherz, G., Rostomyan, T., Sarantsev, A., Schmidt, Ch., Schmieden, H., Seifen, T., Sokhoyan, V., Spieker, K., Thiel, A., Thoma, U., Urban, M., Pee, H. van, Walther, D., Wendel, Ch., Werthmüller, D., Wiedner, U., Wilson, A., Winnebeck, A., Witthauer, L., and Wunderlich, Y.

Published
2021
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22. Double-polarization observable G in neutral-pion photoproduction off the proton

Author

Thiel, A., Eberhardt, H., Lang, M., Afzal, F., Anisovich, A. V., Bantes, B., Bayadilov, D., Beck, R., Bichow, M., Brinkmann, K. -T., Böse, S., Crede, V., Dieterle, M., Dutz, H., Elsner, D., Ewald, R., Fornet-Ponse, K., Friedrich, St., Frommberger, F., Funke, Ch., Goertz, St., Gottschall, M., Gridnev, A., Grüner, M., Gutz, E., Hammann, D., Hammann, Ch., Hannappel, J., Hartmann, J., Hillert, W., Hoffmeister, Ph., Honisch, Ch., Jude, T., Kaiser, D., Kalinowsky, H., Kalischewski, F., Kammer, S., Keshelashvili, I., Klassen, P., Kleber, V., Klein, F., Klempt, E., Koop, K., Krusche, B., Kube, M., Lopatin, I., Mahlberg, Ph., Makonyi, K., Metag, V., Meyer, W., Müller, J., Müllers, J., Nanova, M., Nikonov, V., Piontek, D., Reeve, S., Reicherz, G., Runkel, S., Sarantsev, A., Schmidt, Ch., Schmieden, H., Seifen, T., Sokhoyan, V., Spieker, K., Thoma, U., Urban, M., van Pee, H., Walther, D., Wendel, Ch., Wilson, A., Winnebeck, A., Witthauer, L., and The CBELSA/TAPS Collaboration

Published
2017
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23. Mechanisms of Photo Double Ionization of Helium by 530 eV Photons

Author

Knapp, A., Kheifets, A., Bray, I., Weber, Th., Landers, A. L., Schössler, S., Jahnke, T., Nickles, J., Kammer, S., Jagutzki, O., Schmidt, L. Ph., Osipov, T., Rösch, J., Prior, M. H., Schmidt-Böcking, H., Cocke, C. L., Dörner, R., Burke, P. G., editor, Kleinpoppen, H., editor, Whelan, Colm T., editor, and Mason, Nigel J., editor

Published
2005
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24. Photoproduction of ω mesons off protons and neutrons

Author

Dietz, F., Metag, V., Anisovich, A. V., Bacelar, J. C. S., Bantes, B., Bartholomy, O., Bayadilov, D. E., Beck, R., Belogazov, Y. A., Castelijns, R., Crede, V., Dutz, H., Elsner, D., Ewald, R., Frommberger, F., Funke, C., Gothe, R., Gregor, R., Gridnev, A. B., Gutz, E., Hillert, W., Höffgren, S., Hoffmeister, P., Horn, I., Jaegle, I., Junkersfeld, J., Kalinowsky, H., Kammer, S., Kleber, V., Klein, Frank, Klein, Friedrich, Klempt, E., Konrad, M., Kotulla, M., Krusche, B., Lang, M., Löhner, H., Lopatin, I. V., Lugert, S., Menze, D., Mertens, T., Messchendorp, J. G., Nikonov, V. A., Nanova, M., Novinski, D. V., Novotny, R., Ostrick, M., Pant, L. M., van Pee, H., Pfeiffer, M., Rostomyan, T., Roy, A., Schadmand, S., Schmidt, C., Schmieden, H., Schoch, B., Shende, S. V., Shklyar, V., Süle, A., Sumachev, V. V., Szczepanek, T., Thoma, U., Trnka, D., Varma, R., Walter, D., Wendel, C., Wilson, A., and The CBELSA/TAPS Collaboration

Published
2015
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25. Measurement of the beam asymmetry Σ in π 0 η production off the proton with the CBELSA/TAPS experiment

Author

The CBELSA/TAPS Collaboration, Gutz, E., Sokhoyan, V., van Pee, H., Anisovich, A. V., Bacelar, J. C. S., Bantes, B., Bartholomy, O., Bayadilov, D., Beck, R., Beloglazov, Y. A., Castelijns, R., Credé, V., Dutz, H., Ehmanns, A., Elsner, D., Essig, K., Ewald, R., Fabry, I., Fornet-Ponse, K., Fuchs, M., Funke, Ch., Gothe, R., Gregor, R., Gridnev, A. B., Höffgen, St., Hoffmeister, P., Horn, I., Jägle, I., Junkersfeld, J., Kalinowsky, H., Kammer, S., Kleber, V., Klein, Friedrich, Klein, Frank, Klempt, E., Konrad, M., Kotulla, M., Krusche, B., Lang, M., Langheinrich, J., Löhner, H., Lopatin, I. V., Lotz, J., Lugert, S., Menze, D., Mertens, T., Messchendorp, J. G., Metag, V., Morales, C., Nanova, M., Nikonov, V. A., Novinsky, D., Novotny, R., Ostrick, M., Pant, L., Pfeiffer, M., Radkov, A., Sarantsev, A. V., Schadmand, S., Schmidt, Ch., Schmieden, H., Schoch, B., Shende, S., Süle, A., Sumachev, V. V., Szczepanek, T., Thoma, U., Trnka, D., Walther, D., Weinheimer, Ch., Wendel, Ch., Hammer, Hans-Werner, editor, Kleber, Vera, editor, Thoma, Ulrike, editor, and Schmieden, Hartmut, editor

Published
2008
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26. High statistics study of the reaction γp → pπ0 η

Author

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

Published
2014
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27. Photoproduction of $ \eta{^\prime}$ -mesons off the deuteron

Author

Jaegle, I., Mertens, T., Fix, A., Huang, F., Nakayama, K., Tiator, L., Anisovich, A. V., Bacelar, J. C. S., Bantes, B., Bartholomy, O., Bayadilov, D. E., Beck, R., Beloglazov, Y. A., Castelijns, R., Crede, V., Dutz, H., Elsner, D., Ewald, R., Frommberger, F., Funke, C., Gregor, R., Gridnev, A. B., Gutz, E., Hillert, W., Höffgen, S., Junkersfeld, J., Kalinowsky, H., Kammer, S., Kleber, V., Klein, Frank, Klein, Friedrich, Klempt, E., Kotulla, M., Krusche, B., Lang, M., Löhner, H., Lopatin, I. V., Lugert, S., Menze, D., Messchendorp, J. G., Metag, V., Nikonov, V. A., Nanova, M., Novinski, D. V., Novotny, R., Ostrick, M., Pant, L. M., van Pee, H., Pfeiffer, M., Roy, A., Sarantsev, A. V., Schadmand, S., Schmidt, C., Schmieden, H., Schoch, B., Shende, S. V., Sokhoyan, V., Süle, A., Sumachev, V. V., Szczepanek, T., Thoma, U., Trnka, D., Varma, R., Walther, D., Wendel, C., and The CBELSA/TAPS Collaboration

Published
2011
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28. New data on [formula omitted] with polarized photons and protons and their implications for N⁎ → Nη decays

Author

Müller, J., Hartmann, J., Grüner, M., Afzal, F., Anisovich, A.V., Bantes, B., Bayadilov, D., Beck, R., Becker, M., Beloglazov, Y., Berlin, A., Bichow, M., Böse, S., Brinkmann, K.-T., Challand, T., Crede, V., Dietz, F., Dieterle, M., Drexler, P., Dutz, H., Eberhardt, H., Elsner, D., Ewald, R., Fornet-Ponse, K., Friedrich, S., Frommberger, F., Funke, C., Gottschall, M., Gridnev, A., Goertz, S., Gutz, E., Hammann, C., Hannen, V., Hannappel, J., Herick, J., Hillert, W., Hoffmeister, P., Honisch, C., Jahn, O., Jude, T., Jaegle, I., Käser, A., Kaiser, D., Kalinowsky, H., Kalischewski, F., Kammer, S., Keshelashvili, I., Klassen, P., Kleber, V., Klein, F., Klempt, E., Koop, K., Krusche, B., Kube, M., Lang, M., Lopatin, I., Maghrbi, Y., Mahlberg, P., Makonyi, K., Messi, F., Metag, V., Meyer, W., Müllers, J., Nanova, M., Nikonov, V., Novinski, D., Novotny, R., Piontek, D., Reicherz, G., Rosenbaum, C., Rostomyan, T., Roth, B., Sarantsev, A., Schmidt, C., Schmieden, H., Schmitz, R., Seifen, T., Sokhoyan, V., Thiel, A., Thoma, U., Urban, M., van Pee, H., Walther, D., Wendel, C., Wiedner, U., Wilson, A., Winnebeck, A., and Witthauer, L.

Published
2020
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29. K0πand K*0Σ+ photoproduction off the proton

Author

Nanova, M., Bacelar, J. C. S., Bantes, B., Bartholomy, O., Bayadilov, D., Beck, R., Beloglazov, Y. A., Castelijns, R., Crede, V., Dutz, H., Ehmanns, A., Elsner, D., Essig, K., Ewald, R., Fabry, I., Fornet-Ponse, K., Fuchs, M., Funke, Ch., Gothe, R., Gregor, R., Gridnev, A. B., Gutz, E., Hoffmeister, P., Horn, I., Jaegle, I., Junkersfeld, J., Kalinowsky, H., Kammer, S., Kleber, V., Klein, Frank, Klein, Friedrich, Klempt, E., Konrad, M., Kotulla, M., Krusche, B., Lang, M., Langheinrich, J., Löhner, H., Lopatin, I. V., Lotz, J., Lugert, S., Menze, D., Messchendorp, J. G., Mertens, T., Metag, V., Morales, C., Novinski, D. V., Novotny, R., Ostrick, M., Pant, L. M., van Pee, H., Pfeiffer, M., Radkov, A., Roy, A., Schadmand, S., Schmidt, Ch., Schmieden, H., Schoch, B., Shende, S. V., Sokhoyan, V., Süle, A., Sumachev, V. V., Szczepanek, T., Thoma, U., Trnka, D., Varma, R., Walther, D., Weinheimer, Ch., Wendel, Ch., and The CBELSA/TAPS Collaboration

Published
2008
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30. Nucleon resonance decay by the K0Σchannel

Author

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

Published
2008
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31. Measurement of the beam asymmetry in η photoproduction off the proton

Author

Elsner, D., Anisovich, A. V., Anton, G., Bacelar, J. C. S., Bantes, B., Bartholomy, O., Bayadilov, D. E., Beck, R., Beloglazov, Y. A., Bogendörfer, R., Castelijns, R., Crede, V., Dutz, H., Ehmanns, A., Essig, K., Ewald, R., Fabry, I., Flemming, H., Fornet-Ponse, K., Fuchs, M., Funke, C., Gothe, R., Gregor, R., Gridnev, A. B., Gutz, E., Höffgen, S., Hoffmeister, P., Horn, I., Hössl, J., Jaegle, I., Junkersfeld, J., Kalinowsky, H., Kammer, S., Kleber, V., Klein, Frank, Klein, Friedrich, Klempt, E., Koch, H., Konrad, M., Kopf, B., Kotulla, M., Krusche, B., Lang, M., Langheinrich, J., Löhner, H., Lopatin, I. V., Lotz, J., Lugert, S., Matthäy, H., Menze, D., Mertens, T., Messchendorp, J. G., Metag, V., Morales, C., Nanova, M., Nikonov, V. A., Novinski, D. V., Novotny, R., Ostrick, M., Pant, L. M., van Pee, H., Pfeiffer, M., Radkov, A. K., Sarantsev, A. V., Schadmand, S., Schmidt, C., Schmieden, H., Schoch, B., Shende, S., Suft, G., Süle, A., Sumachev, V. V., Szczepanek, T., Thoma, U., Trnka, D., Walther, D., Weinheimer, C., Wendel, C., and The CBELSA/TAPS Collaboration

Published
2007
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32. New data on With Polarized Photons and Protons and Their Implications for → Decays

Author

Müller, J., Hartmann, J., Grüner, M., Afzal, F., Anisovich, A.V., Bantes, B., Bayadilov, D., Beck, R., Becker, M., Beloglazov, Y., Berlin, A., Bichow, M., Böse, S., Brinkmann, K.T., Challand, T., Crede, V., Dietz, F., Dieterle, M., Drexler, P., Dutz, H., Eberhardt, H., Elsner, D., Ewald, R., Fornet-Ponse, K., Friedrich, S., Frommberger, F., Funke, C., Gottschall, M., Gridnev, A., Goertz, S., Gutz, E., Hammann, C., Hannen, V., Hannappel, J., Herick, J., Hillert, W., Hoffmeister, P., Honisch, C., Jahn, O., Jude, T., Jaegle, I., Käser, A., Kaiser, D., Kalinowsky, H., Kalischewski, F., Kammer, S., Keshelashvili, I., Klassen, P., Kleber, V., Klein, F., Klempt, E., Koop, K., Krusche, B., Kube, M., Lang, M., Lopatin, I., Maghrbi, Y., Mahlberg, P., Makonyi, K., Messi, F., Metag, V., Meyer, W., Müllers, J., Nanova, M., Nikonov, V., Novinski, D., Novotny, R., Piontek, D., Reicherz, G., Rosenbaum, C., Rostomyan, T., Roth, B., Sarantsev, A., Schmidt, C., Schmieden, H., Schmitz, R., Seifen, T., Sokhoyan, V., Thiel, A., Thoma, U., Urban, M., van Pee, H., Walther, D., Wendel, C., Wiedner, U., Wilson, A., Winnebeck, A., and Witthauer, L.

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, JüBo, 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 JP=1/2−-resonances significantly.

Published
2020

33. 'Wie machen wir’s nun'. Worldmaking in Wilhelm Raabes 'Vom alten Proteus'

Author

Kammer, Stephan, Krauthausen, Karin, Kammer, S ( Stephan ), Krauthausen, K ( Karin ), Pierstorff, Cornelia; https://orcid.org/0000-0002-2058-4424, Kammer, Stephan, Krauthausen, Karin, Kammer, S ( Stephan ), Krauthausen, K ( Karin ), and Pierstorff, Cornelia; https://orcid.org/0000-0002-2058-4424

Published
2020

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

Author

Gottschall, M., primary, Afzal, F., additional, Anisovich, A. V., additional, Bayadilov, D., additional, Beck, R., additional, Bichow, M., additional, Brinkmann, K. Th., additional, Crede, V., additional, Dieterle, M., additional, Dietz, F., additional, Dutz, H., additional, Eberhardt, H., additional, Elsner, D., additional, Ewald, R., additional, Fornet-Ponse, K., additional, Friedrich, St., additional, Frommberger, F., additional, Gridnev, A., additional, Grüner, M., additional, Gutz, E., additional, Hammann, Ch., additional, Hannappel, J., additional, Hartmann, J., additional, Hillert, W., additional, Hoffmeister, Ph., additional, Honisch, Ch., additional, Jude, T., additional, Kammer, S., additional, Kalinowsky, H., additional, Keshelashvili, I., additional, Klassen, P., additional, Klein, F., additional, Klempt, E., additional, Koop, K., additional, Krusche, B., additional, Kube, M., additional, Lang, M., additional, Lopatin, I., additional, Mahlberg, P., additional, Makonyi, K., additional, Metag, V., additional, Meyer, W., additional, Müller, J., additional, Müllers, J., additional, Nanova, M., additional, Nikonov, V., additional, Novotny, R., additional, Piontek, D., additional, Reicherz, G., additional, Rostomyan, T., additional, Sarantsev, A., additional, Schmidt, Ch., additional, Schmieden, H., additional, Seifen, T., additional, Sokhoyan, V., additional, Spieker, K., additional, Thiel, A., additional, Thoma, U., additional, Urban, M., additional, Pee, H. van, additional, Walther, D., additional, Wendel, Ch., additional, Werthmüller, D., additional, Wiedner, U., additional, Wilson, A., additional, Winnebeck, A., additional, Witthauer, L., additional, and Wunderlich, Y., additional

Published
2021
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36. New data on γ→p→→ηp with polarized photons and protons and their implications for N⁎ → Nη decays

Author

Müller, J., primary, Hartmann, J., additional, Grüner, M., additional, Afzal, F., additional, Anisovich, A.V., additional, Bantes, B., additional, Bayadilov, D., additional, Beck, R., additional, Becker, M., additional, Beloglazov, Y., additional, Berlin, A., additional, Bichow, M., additional, Böse, S., additional, Brinkmann, K.-T., additional, Challand, T., additional, Crede, V., additional, Dietz, F., additional, Dieterle, M., additional, Drexler, P., additional, Dutz, H., additional, Eberhardt, H., additional, Elsner, D., additional, Ewald, R., additional, Fornet-Ponse, K., additional, Friedrich, S., additional, Frommberger, F., additional, Funke, C., additional, Gottschall, M., additional, Gridnev, A., additional, Goertz, S., additional, Gutz, E., additional, Hammann, C., additional, Hannen, V., additional, Hannappel, J., additional, Herick, J., additional, Hillert, W., additional, Hoffmeister, P., additional, Honisch, C., additional, Jahn, O., additional, Jude, T., additional, Jaegle, I., additional, Käser, A., additional, Kaiser, D., additional, Kalinowsky, H., additional, Kalischewski, F., additional, Kammer, S., additional, Keshelashvili, I., additional, Klassen, P., additional, Kleber, V., additional, Klein, F., additional, Klempt, E., additional, Koop, K., additional, Krusche, B., additional, Kube, M., additional, Lang, M., additional, Lopatin, I., additional, Maghrbi, Y., additional, Mahlberg, P., additional, Makonyi, K., additional, Messi, F., additional, Metag, V., additional, Meyer, W., additional, Müllers, J., additional, Nanova, M., additional, Nikonov, V., additional, Novinski, D., additional, Novotny, R., additional, Piontek, D., additional, Reicherz, G., additional, Rosenbaum, C., additional, Rostomyan, T., additional, Roth, B., additional, Sarantsev, A., additional, Schmidt, C., additional, Schmieden, H., additional, Schmitz, R., additional, Seifen, T., additional, Sokhoyan, V., additional, Thiel, A., additional, Thoma, U., additional, Urban, M., additional, van Pee, H., additional, Walther, D., additional, Wendel, C., additional, Wiedner, U., additional, Wilson, A., additional, Winnebeck, A., additional, and Witthauer, L., additional

Published
2020
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38. Measurement of the beam asymmetry Σ in πeta; production off the proton with the CBELSA/TAPS experiment⋆

Author

Gutz, E., Sokhoyan, V., van Pee, H., Anisovich, A. V., Bacelar, J. C. S., Bantes, B., Bartholomy, O., Bayadilov, D., Beck, R., Beloglazov, Y. A., Castelijns, R., Credé, V., Dutz, H., Ehmanns, A., Elsner, D., Essig, K., Ewald, R., Fabry, I., Fornet-Ponse, K., Fuchs, M., Funke, Ch., Gothe, R., Gregor, R., Gridnev, A. B., Höffgen, St., Hoffmeister, P., Horn, I., Jägle, I., Junkersfeld, J., Kalinowsky, H., Kammer, S., Kleber, V., Klein, Friedrich, Klein, Frank, Klempt, E., Konrad, M., Kotulla, M., Krusche, B., Lang, M., Langheinrich, J., Löhner, H., Lopatin, I. V., Lotz, J., Lugert, S., Menze, D., Mertens, T., Messchendorp, J. G., Metag, V., Morales, C., Nanova, M., Nikonov, V. A., Novinsky, D., Novotny, R., Ostrick, M., Pant, L., Pfeiffer, M., Radkov, A., Sarantsev, A. V., Schadmand, S., Schmidt, Ch., Schmieden, H., Schoch, B., Shende, S., Süle, A., Sumachev, V. V., Szczepanek, T., Thoma, U., Trnka, D., Walther, D., Weinheimer, Ch., Wendel, Ch., and The CBELSA/TAPS Collaboration

Published
2008
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40. Measurement of the Helicity Asymmetry $E$ for the reaction $ ��p\to ��^0 p$

Author

TAPS Collaboration, Gottschall, M., Afzal, F., Anisovich, A. V., Bayadilov, D., Beck, R., Bichow, M., Brinkmann, K. -Th., Crede, V., Dieterle, M., Dietz, F., Dutz, H., Eberhardt, H., Elsner, D., Ewald, R., Fornet-Ponse, K., Friedrich, St., Frommberger, F., Gridnev, A., Gr��ner, M., Gutz, E., Hammann, Ch., Hannappel, J., Hartmann, J., Hillert, W., Hoffmeister, Ph., Honisch, Ch., Jude, T., Kammer, S., Kalinowsky, H., Keshelashvili, I., Klassen, P., Klein, F., Klempt, E., Koop, K., Krusche, B., Kube, M., Lang, M., Lopatin, I., Mahlberg, P., Makonyi, K., Metag, V., Meyer, W., M��ller, J., M��llers, J., Nanova, M., Nikonov, V., Novotny, R., Piontek, D., Reicherz, G., Rostomyan, T., Sarantsev, A., Schmidt, Ch., Schmieden, H., Seifen, T., Sokhoyan, V., Spieker, K., Thiel, A., Thoma, U., Urban, M., van Pee, H., Walther, D., Wendel, Ch., Werthm��ller, D., Wiedner, U., Wilson, A., Winnebeck, A., Witthauer, L., and Wunderlich, Y.

Subjects
Nuclear Theory, Physics::Accelerator Physics, FOS: Physical sciences, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract

A measurement of the double-polarization observable $E$ for the reaction $��p\to ��^0 p$ is reported. The data were taken with the CBELSA/TAPS experiment at the ELSA facility in Bonn using the Bonn frozen-spin butanol (C$_4$H$_9$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 $E_��=600$~MeV to $E_��=2310$~MeV and nearly the complete angular range. The results are compared to and have been included in recent partial wave analyses., 21 pages

Published
2019
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41. New data on $\vec�� \vec{p}\rightarrow ��p$ with polarized photons and protons and their implications for $N^* \to N��$ decays

Author

M��ller, J., Hartmann, J., Gr��ner, M., Afzal, F., Anisovich, A. V., Bantes, B., Bayadilov, D., Beck, R., Becker, M., Beloglazov, Y., Berlin, M., Bichow, M., B��se, S., Brinkmann, K. -T., Challand, T., Crede, V., Dietz, F., Dieterle, M., Drexler, P., Dutz, H., Eberhardt, H., Elsner, D., Ewald, R., Fornet-Ponse, K., Friedrich, S., Frommberger, F., Funke, C., Gottschall, M., Gridnev, A., Goertz, S., Gutz, E., Hammann, C., Hannen, V., Hannappel, J., Herick, J., Hillert, W., Hoffmeister, P., Honisch, C., Jahn, O., Jude, T., Jaegle, I., K��ser, A., Kaiser, D., Kalinowsky, H., Kalischewski, F., Kammer, S., Keshelashvili, I., Klassen, P., Kleber, V., Klein, F., Klempt, E., Koop, K., Krusche, B., Kube, M., Lang, M., Lopatin, I., Maghrbi, Y., Mahlberg, P., Makonyi, K., Messi, F., Metag, V., Meyer, W., M��llers, J., Nanova, M., Nikonov, V., Novinski, D., Novotny, R., Piontek, D., Reicherz, G., Rosenbaum, C., Rostomyan, T., Roth, B., Sarantsev, A., Schmidt, C., Schmieden, H., Schmitz, R., Seifen, T., Sokhoyan, V., Thiel, A., Thoma, U., Urban, M., van Pee, H., Walther, D., Wendel, C., Wiedner, U., Wilson, A., Winnebeck, A., Witthauer, L., and Collaboration, CBELSA/TAPS

Subjects
Nuclear Theory, FOS: Physical sciences, High Energy Physics::Experiment, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract

The polarization observables $T, E, P, H$, and $G$ in photoproduction of $��$ 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, J��Bo, and BnGa partial-wave analyses. A refit within the BnGa approach including further data yields precise branching ratios for the $N��$ decay of nucleon resonances. A $N��$-branching ratio of $0.33\pm 0.04$ for $N(1650)1/2^-$ is found, which reduces the large and controversially discussed $N��$-branching ratio difference of the two lowest mass $J^P=1/2^-$-resonances significantly., 10 pages, 11 figures

Published
2019
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42. Erratum to: High-statistics study of the reaction $\gamma p\rightarrow p2\pi^{0}$

Author

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

Published
2015
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43. Quasi-free photoproduction of η -mesons off the deuteron

Author

Jaegle, I., Krusche, B., Anisovich, A., Bacelar, J., Bantes, B., Bartholomy, O., Bayadilov, D., Beck, R., Beloglazov, Y., Castelijns, R., Crede, V., Dieterle, M., Dutz, H., Elsner, D., Ewald, R., Frommberger, F., Funke, C., Gothe, R., Gregor, R., Gridnev, A., Gutz, E., Hillert, W., Höffgen, S., Hoffmeister, P., Horn, I., Junkersfeld, J., Kalinowsky, H., Kammer, S., Keshelashvili, I., Kleber, V., Klein, Frank, Klein, Friedrich, Klempt, E., Konrad, M., Kotulla, M., Lang, M., Löhner, H., Lopatin, I., Lugert, S., Maghrbi, Y., Menze, D., Mertens, T., Messchendorp, J., Metag, V., Nikonov, V., Nanova, M., Novinski, D., Novotny, R., Oberle, M., Ostrick, M., Pant, L., van Pee, H., Pfeiffer, M., Pheron, F., Roy, A., Sarantsev, A., Schadmand, S., Schmidt, C., Schmieden, H., Schoch, B., Shende, S., Sokhoyan, V., Süle, A., Sumachev, V., Szczepanek, T., Thoma, U., Trnka, D., Varma, R., Walther, D., Wendel, C., Werthmüller, D., and Witthauer, L.

Subjects
Nuclear Theory, Nuclear Experiment
Abstract

Precise data for quasi-free photoproduction of η-mesons off the deuteron have been measured at the Bonn ELSA accelerator with the combined Crystal Barrel/TAPS detector for incident photon energies up to 2.5GeV. The η-mesons have been detected in coincidence with recoil protons and neutrons. Possible nuclear effects like Fermi motion and re-scattering can be studied via a comparison of the quasi-free reaction off the bound proton to η-production off the free proton. No significant effects beyond the folding of the free cross-section with the momentum distribution of the bound protons have been found. These Fermi motion effects can be removed by an analysis using the invariant mass of the η-nucleon pairs reconstructed from the final-state four-momenta of the particles. The total cross-section for quasi-free η-photoproduction off the neutron reveals even without correction for Fermi motion a pronounced bump-like structure around 1GeV of incident photon energy, which is not observed for the proton. This structure is even narrower in the invariant-mass spectrum of the η-neutron pairs. Position and width of the peak in the invariant-mass spectrum are W ≈ 1665 MeV and FWHM Γ ≈ 25 MeV. The data are compared to the results of different models

Published
2018

44. Data on Is and Ic in γ→p→pπ0π0 reveal cascade decays of N(1900) via N(1520)π

Author

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

Subjects
Nuclear and High Energy Physics
Published
2015
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45. Photoproduction of $ \eta{^\prime}$ -mesons off the deuteron

Author

Jaegle, I., Mertens, T., Fix, A., Huang, F., Nakayama, K., Tiator, L., Anisovich, A., Bacelar, J., Bantes, B., Bartholomy, O., Bayadilov, D., Beck, R., Beloglazov, Y., Castelijns, R., Crede, V., Dutz, H., Elsner, D., Ewald, R., Frommberger, F., Funke, C., Gregor, R., Gridnev, A., Gutz, E., Hillert, W., Höffgen, S., Junkersfeld, J., Kalinowsky, H., Kammer, S., Kleber, V., Klein, Frank, Klein, Friedrich, Klempt, E., Kotulla, M., Krusche, B., Lang, M., Löhner, H., Lopatin, I., Lugert, S., Menze, D., Messchendorp, J., Metag, V., Nikonov, V., Nanova, M., Novinski, D., Novotny, R., Ostrick, M., Pant, L., van Pee, H., Pfeiffer, M., Roy, A., Sarantsev, A., Schadmand, S., Schmidt, C., Schmieden, H., Schoch, B., Shende, S., Sokhoyan, V., Süle, A., Sumachev, V., Szczepanek, T., Thoma, U., Trnka, D., Varma, R., Walther, D., Wendel, C., Jaegle, I., Mertens, T., Fix, A., Huang, F., Nakayama, K., Tiator, L., Anisovich, A., Bacelar, J., Bantes, B., Bartholomy, O., Bayadilov, D., Beck, R., Beloglazov, Y., Castelijns, R., Crede, V., Dutz, H., Elsner, D., Ewald, R., Frommberger, F., Funke, C., Gregor, R., Gridnev, A., Gutz, E., Hillert, W., Höffgen, S., Junkersfeld, J., Kalinowsky, H., Kammer, S., Kleber, V., Klein, Frank, Klein, Friedrich, Klempt, E., Kotulla, M., Krusche, B., Lang, M., Löhner, H., Lopatin, I., Lugert, S., Menze, D., Messchendorp, J., Metag, V., Nikonov, V., Nanova, M., Novinski, D., Novotny, R., Ostrick, M., Pant, L., van Pee, H., Pfeiffer, M., Roy, A., Sarantsev, A., Schadmand, S., Schmidt, C., Schmieden, H., Schoch, B., Shende, S., Sokhoyan, V., Süle, A., Sumachev, V., Szczepanek, T., Thoma, U., Trnka, D., Varma, R., Walther, D., and Wendel, C.

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

46. Measurement of polarisation observables in Ks0Σ+ photoproduction off the proton

Author

Ewald, R., Anisovich, A.V., Bantes, B., Bartholomy, O., Bayadilov, D., Beck, R., Beloglazov, Y.A., Brinkmann, K.-T., Crede, V., Dutz, H., Elsner, D., Fornet-Ponse, K., Frommberger, F., Funke, Ch., Gridnev, A.B., Gutz, E., Hannappel, J., Hillert, W., Hoffmeister, P., Jaegle, I., Jahn, O., Jude, T.C., Junkersfeld, J., Kalinowsky, H., Kammer, S., Kleber, V., Klein, Frank, Klein, Friedrich, Klempt, E., Krusche, B., Lang, M., Löhner, H., Lopatin, I.V., Menze, D., Mertens, T., Messchendorp, J.G., Metag, V., Nanova, M., Nikonov, V.A., Novinski, D., Novotny, R., Ostrick, M., Pant, L., van Pee, H., Roy, A., Sarantsev, A.V., Schadmand, S., Schmidt, C., Schmieden, H., Schoch, B., Shende, S., Sokhoyan, V., Süle, A., Sumachev, V.V., Szczepanek, T., Thoma, U., Trnka, D., Varma, R., Walther, D., and Wendel, Ch.

Subjects
Polarisation in interactions and scattering, Nuclear Theory, Meson production, High Energy Physics::Experiment, Decays of baryons, Other strange mesons, Nuclear Experiment, lcsh:Physics, lcsh:QC1-999, Baryon resonances (SCB0)
Abstract

The reaction γp→KS0Σ+ 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 Eγ=1650MeV. In addition, the recoil hyperon polarisation was determined through the asymmetry in the weak decay Σ+→pπ0 up to Eγ=2250MeV. 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. Keywords: Meson production, Other strange mesons, Baryon resonances (SCB0), Decays of baryons, Polarisation in interactions and scattering

Published
2014

47. Measurement of polarisation observables in K-s(0)Sigma(+) photoproduction off the proton

Author

Ewald R., Anisovich A. V., Bantes B., Bartholomy O., Bayadilov D., Beck R., Beloglazov Y. A., Brinkmann K. -T., Crede V., Dutz H., Elsner D., Fornet-Ponse K., Frommberger F., Funke Ch., Gridnev A. B., Gutz E., Hannappel J., Hillert W., Hoffmeister P., Jaegle I., Jahn O., Jude T. C., Junkersfeld J., Kalinowsky H., and Kammer S.

Published
2014

49. High-statistics study of the reaction gamma p -> p 2 pi(0) (vol 51, pg 95, 2015)

Author

Sokhoyan, V., Gutz, E., Crede, V., van Pee, H., Anisovich, A. V., Bacelar, J. C. S., Bantes, B., Bartholomy, O., Bayadilov, D., Beck, R., Beloglazov, Y. A., Castelijns, R., Dutz, H., Elsner, D., Ewald, R., Frommberger, F., Fuchs, M., Funke, Ch., Gregor, R., Gridnev, A. B., Hillert, W., Hoffmeister, Ph., Horn, I., Jaegle, I., Junkersfeld, J., Kalinowsky, H., Kammer, S., Kleber, V., Klein, Frank, Klein, Friedrich, Klempt, E., Kotulla, M., Krusche, B., Lang, M., Löhner, H., Lopatin, I. V., Lugert, S., Mertens, T., Messchendorp, J. G., Metag, V., Metsch, B., Nanova, M., Nikonov, V. A., Novinsky, D., Novotny, R., Ostrick, M., Pant, L., Pfeiffer, M., Piontek, D., Shende, S., and Research unit Nuclear & Hadron Physics

Published
2015

50. Three-Body Nature of N* and Delta* Resonances from Sequential Decay Chains

Author

Thiel, A., Sokhoyan, V., Gutz, E., van Pee, H., Anisovich, A. V., Bacelar, J. C. S., Bantes, B., Bartholomy, O., Bayadilov, D., Beck, R., Beloglazov, Yu., Castelijns, R., Crede, V., Dutz, H., Elsner, D., Ewald, R., Frommberger, F., Fuchs, M., Funke, Ch., Gregor, R., Gridnev, A., Hillert, W., Hoffmeister, Ph., Horn, I., Jaegle, I., Junkersfeld, J., Kalinowsky, H., Kammer, S., Kleber, V., Klein, Frank, Klein, Friedrich, Klempt, E., Kotulla, M., Krusche, B., Lang, M., Löhner, Herbert, Lopatin, I., Lugert, S., Mertens, T., Messchendorp, J. G., Metag, V., Metsch, B., Nanova, M., Nikonov, V., Novinski, D., Novotny, R., Ostrick, M., Pant, L., Pfeiffer, M., Shende, S., and Research unit Nuclear & Hadron Physics

Subjects
SPECTRUM, BARYON SPECTROSCOPY, STATES, SYMMETRY, Nuclear Theory, PHOTOPRODUCTION, CHIRAL DYNAMICS, High Energy Physics::Experiment, SPECTROMETER, Nuclear Experiment, QUARK-MODEL, ELSA, RESTORATION
Abstract

The N pi(0)pi(0) decays of positive-parity N* and Delta* resonances at about 2 GeV are studied at ELSA by photoproduction of two neutral pions off protons. The data reveal clear evidence for several intermediate resonances: Delta(1232), N(1520)3/2(-), and N(1680)5/2(+), with spin parities J(P) = 3/2(+), 3/2(-), and 5/2(+). The partial wave analysis (within the Bonn-Gatchina approach) identifies N(1440)1/2(+) and the N(pi pi)s (wave) (abbreviated as N sigma here) as further isobars and assigns the final states to the formation of nucleon and Delta resonances and to nonresonant contributions. We observe the know Delta(1232)pi decays of Delta(1910)1/2(+), Delta(1920)3/2(+), Delta(1905)5/2(+), Delta(1950)7/2(+), and of the corresponding spin-parity series in the nucleon sector, N(1880)1/2(+), N(1900)3/2(+), N(2000)5/2(+), and N(1990)7/2(+). For the nucleon resonances, these decay modes are reported here for the first time. Further new decay modes proceed via N(1440)1/2(pi)(+), N(1520)3/2(pi)(-) , N(1680)5/2(pi)(+), and N sigma. The latter decay modes are observed in the decay of N* resonances and at most weakly in Delta(*) decays. It is argued that these decay modes provide evidence for a 3-quark nature of N* resonances rather than a quark-diquark structure.

Published
2015

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