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arXiv · 1504.02221

Measurement of double polarisation asymmetries in $\omega$-photoproduction

H. Eberhardt·T. C. Jude·H. Schmieden·A. V. Anisovich·B. Bantes·D. Bayadilov·R. Beck·Yu. Beloglazov·M. Bichow·S. Boese·K. -Th. Brinkmann·Th. Challand·V. Crede·F. Diez·P. Drexler·H. Dutz·D. Elsner·R. Ewald·K. Fornet-Ponse·St. Friedrich·F. Frommberger·Ch. Funke·M. Gottschall·A. Gridnev·M. Gruener·E. Gutz·Ch. Hammann·J. Hannappel·J. Hartmann·W. Hillert·Ph. Hoffmeister·Ch. Honisch·I. Jaegle·D. Kaiser·H. Kalinowsky·F. Kalischewski·S. Kammer·I. Keshelashvili·V. Kleber·F. Klein·E. Klempt·K. Koop·B. Krusche·M. Kube·M. Lang·I. Lopatin·Y. Maghrbi·K. Makonyi·V. Metag·W. Meyer·J. Mueller·M. Nanova·V. Nikonov·R. Novotny·D. Piontek·S. Reeve·G. Reicherz·T. Rostomyan·S. Runkel·A. Sarantsev·St. Schaepe·Ch. Schmidt·R. Schmitz·T. Seifen·V. Sokhoyan·V. Sumachev·A. Thiel·U. Thoma·M. Urban·H. van Pee·D. Walther·Ch. Wendel·U. Wiedner·A. Wilson·A. Winnebeck
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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 $3/2^-$.

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H. Eberhardt, T. C. Jude, H. Schmieden, A. V. Anisovich, B. Bantes, D. Bayadilov, R. Beck, Yu. Beloglazov, M. Bichow, S. Boese, K. -Th. Brinkmann, Th. Challand, V. Crede, F. Diez, P. Drexler, H. Dutz, D. Elsner, R. Ewald, K. Fornet-Ponse, St. Friedrich, F. Frommberger, Ch. Funke, M. Gottschall, A. Gridnev, M. Gruener, E. Gutz, Ch. Hammann, J. Hannappel, J. Hartmann, W. Hillert, Ph. Hoffmeister, Ch. Honisch, I. Jaegle, D. Kaiser, H. Kalinowsky, F. Kalischewski, S. Kammer, I. Keshelashvili, V. Kleber, F. Klein, E. Klempt, K. Koop, B. Krusche, M. Kube, M. Lang, I. Lopatin, Y. Maghrbi, K. Makonyi, V. Metag, W. Meyer, J. Mueller, M. Nanova, V. Nikonov, R. Novotny, D. Piontek, S. Reeve, G. Reicherz, T. Rostomyan, S. Runkel, A. Sarantsev, St. Schaepe, Ch. Schmidt, R. Schmitz, T. Seifen, V. Sokhoyan, V. Sumachev, A. Thiel, U. Thoma, M. Urban, H. van Pee, D. Walther, Ch. Wendel, U. Wiedner, A. Wilson, A. Winnebeck. 2015-04-09. Measurement of double polarisation asymmetries in $\omega$-photoproduction. https://doi.org/10.1016/j.physletb.2015.09.049

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