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14 results on '"Eberhardt H"'

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 Theory, High Energy Physics::Experiment, 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

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 Theory, Physics::Accelerator Physics, 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. 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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4. 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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5. The $\eta^{\prime}$η-carbon potential at low meson momenta

Author

Nanova, M., Friedrich, S., Brinkmann, K. -T., Crede, V., Drexler, P., Eberhardt, H., Elsner, D., Frommberger, F., Funke, Ch., Gottschall, M., Grüner, M., Gutz, E., Metag, V., Hammann, Ch., Hannappel, J., Hartmann, J., Hillert, W., Hoffmeister, Ph., Honisch, Ch., Jude, T., Kaiser, D., Kalischewski, F., Keshelashvili, I., Paryev, E. Ya., Klein, F., Koop, K., Krusche, B., Lang, M., Makonyi, K., Messi, F., Müller, J., Müllers, J., Piontek, D., Rostomyan, T., Afzal, F. N., Schaab, D., Schmidt, Ch., Schmieden, H., Schmitz, R., Seifen, T., Sokhoyan, V., Sowa, C., Spieker, K., Thiel, A., Thoma, U., Bayadilov, D., Triffterer, T., Urban, M., van Pee, H., Walther, D., Wendel, Ch., Werthmüller, D., Wiedner, U., Wilson, A., Witthauer, L., Wunderlich, Y., Bantes, B., Zaunick, H. -G., Beck, R., Becker, M., and Böse, S.

Subjects
Nuclear Theory, High Energy Physics::Experiment, ddc:530, Nuclear Experiment
Abstract

The production of η′ mesons in coincidence with forward-going protons has been studied in photon-induced reactions on 12C and on a liquid hydrogen (LH2) target for incoming photon energies of 1.3-2.6 GeV at the electron accelerator ELSA. The η′ mesons have been identified via the η′→π0π0η→6γ decay registered with the CBELSA/TAPS detector system. Coincident protons have been identified in the MiniTAPS BaF2 array at polar angles of 2∘≤θp≤11∘. Under these kinematic constraints the η′ mesons are produced with relatively low kinetic energy (≈150 MeV) since the coincident protons take over most of the momentum of the incident-photon beam. For the C-target this allows the determination of the real part of the η′-carbon potential at low meson momenta by comparing with collision model calculations of the η′ kinetic energy distribution and excitation function. Fitting the latter data for η′ mesons going backwards in the center-of-mass system yields a potential depth of V=−(44±16(stat)±15(syst)) MeV, consistent with earlier determinations of the potential depth in inclusive measurements for average η′ momenta of ≈1.1 GeV/c. Within the experimental uncertainties, there is no indication of a momentum dependence of the η′-carbon potential. The LH2 data, taken as a reference to check the data analysis and the model calculations, provide differential and integral cross sections in good agreement with previous results for η′ photoproduction off the free proton.

Published
2018

6. Momentum dependence of the imaginary part of the ω - and η -nucleus optical potential

Author

Friedrich, S., Nanova, M., Metag, V., Afzal, F. N., Bayadilov, D., Bantes, B., Beck, R., Becker, M., Böse, S., Brinkmann, K. T., Crede, V., Drexler, P., Eberhardt, H., Elsner, D., Frommberger, F., Funke, Ch, Gottschall, M., Grüner, M., Gutz, E., Hammann, Ch, Hannappel, J., Hartmann, J., Hillert, W., Hoffmeister, Ph, Honisch, Ch, Jude, T., Kaiser, D., Kalischewski, F., Keshelashvili, I., Klein, F., Koop, K., Krusche, B., Makonyi, K., Messi, F., Müller, J., Müllers, J., Piontek, D. M., Rostomyan, T., Schaab, D., Schmidt, Ch, Schmieden, H., Schmitz, R., Seifen, T., Sokhoyan, V., Sowa, C., Spieker, K., Thiel, A., Thoma, U., Triffterer, T., Urban, M., van Pee, H., Walther, D., Wendel, Ch, Werthmüller, D., Wiedner, U., Witthauer, L., Wunderlich, Y., and Zaunick, H. G.

Subjects
Nuclear Theory, High Energy Physics::Experiment, Nuclear Experiment
Abstract

The photoproduction of ω and η mesons off carbon and niobium nuclei has been measured as a function of the meson momentum for incident photon energies of 1.2-2.9GeV at the electron accelerator ELSA. The mesons have been identified via the ω → π0 γ → 3 γ and η → π0η → 6 γ decays, respectively, registered with the CBELSA/TAPS detector system. From the measured meson momentum distributions the momentum dependence of the transparency ratio has been determined for both mesons. Within a Glauber analysis the in-medium ω and η widths and the corresponding absorption cross sections have been deduced as a function of the meson momentum. The results are compared to recent theoretical predictions for the in-medium ω width and η-N absorption cross sections. The energy dependence of the imaginary part of the ω- and η-nucleus optical potential has been extracted. The finer binning of the present data compared to the existing data allows a more reliable extrapolation towards the production threshold. The modulus of the imaginary part of the η-nucleus potential is found to be about three times smaller than recently determined values of the real part of the η-nucleus potential, which makes the η meson a suitable candidate for the search for meson-nucleus bound states. For the ω meson, the modulus of the imaginary part near threshold is comparable to the modulus of the real part of the potential. As a consequence, only broad structures can be expected, which makes the observation of ω mesic states very difficult experimentally.

Published
2016

7. Momentum dependence of the imaginary part of the $��$- and $��^\prime$-nucleus optical potential

Author

Friedrich, S., Nanova, M., Metag, V., Afzal, F. N., Bayadilov, D., Bantes, B., Beck, R., Becker, M., B��se, S., Brinkmann, K. -T., Crede, V., Drexler, P., Eberhardt, H., Elsner, D., Frommberger, F., Funke, Ch., Gottschall, M., Gr��ner, M., Gutz, E., Hammann, Ch., Hannappel, J., Hartmann, J., Hillert, W., Hoffmeister, Ph., Honisch, Ch., Jude, T., Kaiser, D., Kalischewski, F., Keshelashvili, I., Klein, F., Koop, K., Krusche, B., Lang, M., Makonyi, K., Messi, F., M��ller, J., M��llers, J., Piontek, D. -M., Rostomyan, T., Schaab, D., Schmidt, Ch., Schmieden, H., Schmitz, R., Seifen, T., Sokhoyan, V., Sowa, C., Spieker, K., Thiel, A., Thoma, U., Triffterer, T., Urban, M., van Pee, H., Walther, D., Wendel, Ch., Werthm��ller, D., Wiedner, U., Wilson, A., Witthauer, L., Wunderlich, Y., and Zaunick, H. -G.

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

The photoproduction of $��$ and $��^\prime$ mesons off carbon and niobium nuclei has been measured as a function of the meson momentum for incident photon energies of 1.2-2.9 GeV at the electron accelerator ELSA. The mesons have been identified via the $��\rightarrow ��^0 ��\rightarrow 3 ��$ and $��^\prime\rightarrow ��^0 ��^0��\rightarrow 6 ��$ decays, respectively, registered with the CBELSA/TAPS detector system. From the measured meson momentum distributions the momentum dependence of the transparency ratio has been determined for both mesons. Within a Glauber analysis the in-medium $��$ and $��^\prime$ widths and the corresponding absorption cross sections have been deduced as a function of the meson momentum. The results are compared to recent theoretical predictions for the in-medium $��$ width and $��^\prime$-N absorption cross sections. The energy dependence of the imaginary part of the $��$- and $��^\prime$-nucleus optical potential has been extracted. The finer binning of the present data compared to the existing data allows a more reliable extrapolation towards the production threshold. The modulus of the imaginary part of the $��^\prime$ nucleus potential is found to be about three times smaller than recently determined values of the real part of the $��^\prime$-nucleus potential, which makes the $��^\prime$ meson a suitable candidate for the search for meson-nucleus bound states. For the $��$ meson, the modulus of the imaginary part near threshold is comparable to the modulus of the real part of the potential. As a consequence, only broad structures can be expected which makes the observation of $��$ mesic states very difficult experimentally., 10 pages, 8 figures

Published
2016
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8. The polarization observables T , P , and H and their impact on γp→pπ0 multipoles

Author

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

Subjects
Polarization observables, Baryon spectroscopy, Nuclear Theory, Nuclear Experiment, Multipoles, Meson photoproduction, lcsh:Physics, lcsh:QC1-999
Abstract

Data on the polarization observables T , P , and H for the reaction γp→pπ0 are reported. Compared to earlier data from other experiments, our data are more precise and extend the covered range in energy and angle substantially. The results were extracted from azimuthal asymmetries measured using a transversely polarized target and linearly polarized photons. The data were taken at the Bonn electron stretcher accelerator ELSA with the CBELSA/TAPS detector. Within the Bonn-Gatchina partial wave analysis, the new polarization data lead to a significant narrowing of the error band for the multipoles for neutral-pion photoproduction.

Published
2015

9. The polarization observables T, P, and H and their impact on $\gamma p \to p\pi^0$ multipoles

Author

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

Subjects
Nuclear Theory, Nuclear Experiment
Abstract

Data on the polarization observables T, P, and H for the reaction $\gamma p\to p\pi^0$ are reported. Compared to earlier data from other experiments, our data are more precise and extend the covered range in energy and angle substantially. The results were extracted from azimuthal asymmetries measured using a transversely polarized target and linearly polarized photons. The data were taken at the Bonn electron stretcher accelerator ELSA with the CBELSA/TAPS detector. Within the Bonn-Gatchina partial wave analysis, the new polarization data lead to a significant narrowing of the error band for the multipoles for neutral-pion photoproduction.

Published
2015

10. The polarization observables T, P, and H and their impact on $��p \to p��^0$ multipoles

Author

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

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

Data on the polarization observables T, P, and H for the reaction $��p\to p��^0$ are reported. Compared to earlier data from other experiments, our data are more precise and extend the covered range in energy and angle substantially. The results were extracted from azimuthal asymmetries measured using a transversely polarized target and linearly polarized photons. The data were taken at the Bonn electron stretcher accelerator ELSA with the CBELSA/TAPS detector. Within the Bonn-Gatchina partial wave analysis, the new polarization data lead to a significant narrowing of the error band for the multipoles for neutral-pion photoproduction.

Published
2015
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11. Experimental constraints on the $��$-nucleus real potential

Author

Friedrich, S., Makonyi, K., Metag, V., Bayadilov, D., Bantes, B., Beck, R., Beloglazov, Y. A., B��se, 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., Gr��ner, 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., M��ller, 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 Theory, FOS: Physical sciences, High Energy Physics::Experiment, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract

In a search for $��$ mesic states, the production of $��$-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 $��^0 ��$ pairs from decays of bound or quasi-free $��$-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 $��^0 ��$ pairs, which would indicate the population and decay of bound $��~^{11}$B states, are not observed. The $��^0 ��$ 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 $��$-meson. A comparison of the measured total energy distribution with calculations suggests the real part $V_0$ of the $��~^{11}$B potential to be small and only weakly attractive with $V_0(��=��_0) = -15\pm$ 35(stat) $\pm$20(syst) MeV in contrast to some theoretical predictions of attractive potentials with a depth of 100 - 150 MeV., 13 pages, 8 figures

Published
2014
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12. 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 Theory, 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

13. Determination of the ��'-nucleus optical potential

Author

Nanova, M., Metag, V., Paryev, E. Ya., Bayadilov, D., Bantes, B., Beck, R., Beloglazov, Y. A., B��se, 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., Gr��ner, 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., M��ller, 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 Theory, FOS: Physical sciences, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract

The excitation function and momentum distribution of $��^\prime$ 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 $��^\prime$-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 $��^\prime$-nucleus potential of -($10\pm2.5$) MeV, determined by transparency ratio measurements, a search for resolved $��^\prime$-bound states appears promising., 13 pages, 6 figures

Published
2013
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14. First measurement of the helicity asymmetry for $��p\rightarrow p��^0$ in the resonance region

Author

Gottschall, M., Anisovich, A. V., Bantes, B., Bayadilov, D., Beck, R., Bichow, M., B��se, 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., Gr��ner, 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., M��ller, 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 Theory, FOS: Physical sciences, Nuclear Experiment (nucl-ex), 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
Full Text
View/download PDF

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